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Spaces, Paths, Paces (Part 1)

Objective

Development processes start with requirements and wind up in code; in between there isn’t much of a consensus among the software engineering community about how to define the scope (spaces), how to sequence the tasks (paths), and how to time deliveries (paces). On one side of the debate phased approaches hope for fixed spaces and ordered paths but often get entangled in moving lines. On the other side of the debate agile teams try to find their space by increments but risk losing the path while still on their way.

ibrahim-mohammed-el-salahi-1346719712_b — Maze revisited: finding a path while building the space (Ibrahim El-Salahi)

This lack of agreed upon concepts and principles entrusts personal skills and best practices as primary success factors. Conversely, that could explain the rate of failures for software projects, significantly higher than for “hard” engineering ones; given the quasi absence of physical constraints, the opposite would have been expected, which would suggest some critical intrinsic flaw.

With the “benefits” of hindsight and agile assessment of waterfall flaws, the focus has been put on fixed scope and schedule, in particular with regard to requirements and quality management:

Fixed requirements set upfront: since there is an inverse relationship between the level of details and the reliability and stability of requirements, staking the whole project on requirements fully defined at such an early time is arguably a very hazardous policy.
Quality as an afterthought: given that finding defects is not very gratifying when undertaken in isolation, delegating the task will offer few guarantees if not associated with rewards commensurate to findings; moreover, quality as a detached concern may easily turn into a collateral damage when set along mounting costs and scheduling constraints. Alternatively, quality checks may change into a more positive endeavor when conducted as an intrinsic part of development.

Agile answer to those failings has been to conduct specifications, development, and quality assurance into integrated iterations. As a consequence, the definition of scope becomes a byproduct of development cycles, with requirements itemized as features in order to be developed progressively. Moreover, with specifications and schedules managed dynamically, timetables become impracticable and deliveries can only be carried out by shuttles.

The agile “reformation” has open new perspectives and beget many fruitful practices, and the objective here is to see how those approaches of scope and schedule can be reformulated within the perspective of architecture layers. This part examines the congruence between the alternate flows of use cases and the backlog of users’ stories, and considers their complementarity as path-finders. The second part will focus on the role of time-boxes as pace-makers and the benefits for quality assurance.

Architectures and Projects Scope

Whatever the compass, agile or phased, projects footprint can be set across three architecture layers:

Enterprise architectures describe business environments and objectives, resources and regulatory constraints.
System architectures describe enterprises in terms of functional entities of human agents and physical and software assets.
Technical architectures describe the platforms supporting functional entities.

Projects are meant to carry out changes within architectures initiated by business, engineering, or services management processes:

Business processes are defined by business environment and objectives. Changes may have to deal with domains and activities, organization and supported operations, and quality of service as experienced by users.
Engineering processes focus on the development of software systems supporting business processes: business domains and applications, system functionalities, platform implementations.
Services management stand between engineering deliveries and operational concerns: location of assets, access to services, releases deployment, and systems configuration.

While development projects may (and will usually) cross architecture layers, their roots and stakes should nonetheless be clearly positioned if projects are to be planned within the respective time-spans, governed by the relevant authority, and their products accepted by the right stakeholders.

Development Project, from Requirements to Deployments

That put projects governance at crossroads between (a) business objectives set by market opportunities, (b) the deployment of features into functional architectures, and (c) the deployment of releases according to changes in technical architecture. With phased developments, scope and schedules are fixed upfront, which means that the business layer forces its time-frame over the ones of system and technical layers, which may introduce frictions regarding scope as well as quality:

With regard to scope, frictions stem from features and schedules set fully and definitively at enterprise level, independently of any feedback from functional and technical layers.
With regard to quality, frictions stem from tests performed at technical layer when scope and schedules can no longer be revised in case of negative outcomes.

The consequences are all too easy to observe, with business needs partially satisfied and software quality sacrificed. Hence the need of a balanced approach that would consolidate the different maps and time-frames in order to minimize frictions between layers.

Mapping Project Scope

Projects scope can be described along two dimensions, one set by business logic, the other by system functionalities:

First, one have to circumscribe the business variants to be taken into consideration. For that purpose the project footprint, first introduced as users’ stories, will have to be documented by activity or business process diagrams.
Then, the project scope will have to mark out the subset of business requirements to be supported by system functionalities. That will usually be done with use cases describing interactions between system and users.

Complementary descriptions of projects footprints: use cases (interactions between users and system) and activity diagrams (business logic).

That makes those descriptions both orthogonal and complementary: orthogonal because use cases cut across activity diagrams, complementary because use cases are meaningless without targeted activities.

More importantly, they are associated with different architecture layers and governed by different concerns:

At business level (business processes or activities), the perimeter and granularity of requirements must be congruent with the continuity and consistency constraints of business objects and operations.
At functional level (use cases), the span and granularity of interactions between system and users must coincide with execution paths. But the rationale governing users interactions is not the same as the one governing the integrity of business processes. As a consequence, the paths considered for development may pick sequences of operations defined by business processes but should not define them anew based upon interaction constraints.
Finally, assuming that use cases see systems as black-boxes, their footprint should not depend on decisions taken at technical level.

Those concerns can be dealt with separately if projects scope is explored iteratively, e.g using activity diagrams for business logic and use case diagrams for users interactions.

Iterative Mapping of Project Footprint

Iterative development is not just about increments but, first and foremost, about exploring development spaces. That is especially useful when projects overlap architecture layers and cannot rely on fully fledged requirements.

Such projects have to deal with two challenges:

They must identify and manage work units according to the state of requirements and the nature of dependencies (business, organization, or technology, …).
They must carry on with developments based on incomplete specifications while exploring alternatives and deferring decisions until the “last responsible moment” when further delay would limit the options at hand.

Taking a leaf out of the agile book, projects should be driven by users’ value, with requirements first introduced as users’ stories. From that springboard, as informal and incomplete as could be, stories must be fleshed out and organized in order to support the reasoned exploration of project scope.

At inception stories are no more than a user, an objective, and an activity, all set at business level independently of the part played by systems. Scope exploration must therefore begin with activities backbone and be furthered with variants, aka scenarii.

cccc — Adding execution paths to project scope

Given a set of business scenarii, the candidates for system support must be ordered and mapped to system features, actual or planned. That should provide a blueprint for development paths. Unfortunately, as variants are added to plots, narratives can easily turn messy, mixing features and capabilities across architecture layers. And that’s where the benefits of use cases are to be found.

Development Paths: From Users’ Stories to Use Cases

Whatever the context, iterations are formal constructs defined by invariants, increments, and exit conditions. When applied to development spaces, iterations are defined by:

Invariants: conditions on architectural assets supporting the scenario under consideration.
Increments: features or variants added to scenarii.
Exit condition: no more features or variants (empty backlog) or time-out.

Applied to architecture layers, invariants provide for reasoned iterations and backlogs:

Enterprise layer are the first to be considered: cycles are set for persistency and execution units and bound by domains (identification mechanisms, integrity constraints, and semantics); within cycles, increments target attributes, operations and variants.
Functional layer come second: cycles are set for interaction units (aka use cases), and bound by the continuity and consistency business objects and activities; increments target transient attributes and operations.
Technical layer come last: cycles are set for platforms and bound by functional units.

But there is a catch: while users’ stories and activity (or business process) diagrams are set at enterprise level, development projects are considered at system level; because systems functionalities are not supposed to appear in users’ stories or activity diagrams, there could be a gap between business and functional requirements. As it happens, use cases provide a bridge: on one hand they focus on the interactions between users and systems, on the other hand their basic and alternate flows can be directly mapped to the paths in activity diagrams.

From alternative flows to Development Paths

That provides a clear and sound basis for the definition of development paths: on one hand alternate flows can be ranked according users’ priorities; on the other hand they determine the sequence of use cases that will have to be developed.

Backlogs and Pathfinders

While the objective of users’ stories is to tie up projects in business value, the objective of use cases is to anchor them in the context of system functionalities. That perspective, and the role of models, may be ignored for standalone projects, but it is necessary when project development paths are to be governed both by business and functional dependencies, described respectively by users’ stories and use cases.

In that case the exploration of development paths should be guided by invariants set along MDA model layers: computation independent (business processes), platform independent (systems functionalities), and platform specific (technology platforms).

Projects are rooted in use cases but development paths are governed by users' stories. — Projects are rooted in use cases but development paths are governed by users’ stories.

When projects are rooted in business activities (a), e.g the possibility of upgrading a customer, stories describe execution paths and are ranked according business priorities. Iterations will proceed with development and new cycles added for alternative paths to the basic one.

Depending on context dependencies, development projects can be directly initiated from given sequences of activities (b) or conducted in parallel with users’ stories. Use cases remain the option of choice when the features supporting users’ stories are meant to be shared (e.g checkout). In that case the development paths are governed both by users’ value and functional dependencies. When features are deemed specific (e.g upgrade), use cases can be bypassed and development paths explored simultaneously according users’ and development concerns.

Backlog organization is more complex when development paths cross the divide between functional and technical concerns. Ideally, one would expect a clear separation of concerns, with use cases defined independently of technical options, just like business logic doesn’t depend on system functionalities. But alternatives may be blurred due to the dependencies between interactions design and platform capabilities, the risk being to associate technical options with functional variants, e.g specialized use cases.

Entangled development paths: self check out depends on technical platform.

That’s the case when features can only be implemented on specific platforms. If those features are also specific the corresponding development cycle can be managed as a whole. Otherwise the relevant decisions should be factored out. The same principle applies for features supporting different business processes.

Squaring the Circles: From Epics to Releases

Iterations run within boundaries set by invariants, and with regard to projects scope, those invariants are set by architecture capabilities: enterprise on one hand, systems on the other hand.

From the enterprise perspective, development projects (b) are meant to support business objectives (a), not to define them. As a consequence, users’ stories must remain within borders set upfront. That can be achieved by introducing business projects (aka strategies, aka epics) and portfolios of development ones.

Development Paths: (a) Portfolio of business objectives with associated users' stories and architectural capabilities; (b) targeted features; (c) releases. — Development Paths: Portfolio of business objectives (a), associated backlogs of users’ stories (b), targeted features (c), architectural capabilities (d), and releases (e).

From the system perspective, a clear distinction should be maintained between projects supported by platforms capabilities (b), and projects targeting platforms capabilities (d). Eventually, those different levels of explorations will have to be consolidated as releases (e), and that is where one may find the agile answer to waterfall.

A Time for Every Purpose: Time-boxes as Pace-Makers

As Einstein famously said, “The only reason for time is so that everything doesn’t happen at once.” In other words time is what happens between events, and the use of a single time-frame will put all events under the same rationale.

But architectures are best understood as shearing layers whose events are governed by different rationales, respectively: business opportunities, engineering constraints, or operational needs.

That is arguably the critical flaw of waterfall solutions as they force business, development, and operations under the same set of strictures. And that’s why agile’s solution to components release may be its pivotal innovation as it establishes the autonomy of those three layers and introduces time-boxes as their pace-makers.

Spaces, Paths, Paces (Part 2)

Objective

As previously noted, embarking for sizable and lengthy project on the assumption that detailed scope and schedules can be set upfront is a very hazardous policy. Alternatively, agile development models carry out specifications, development, and quality assurance into integrated iterations, making room for a progressive exploration of problem spaces and solution paths, and consequently for informed decision-making and better risk management.

Yet, whatever the method, at some point, scope and features will have to be committed; and with targeted features set dynamically, planned schedules are no more an option. Hence the need to reconsider the way time is taken into account.

Dependencies: Playing for Time

Paraphrasing Einstein, one may say that the only reason for processes is so that everything doesn’t happen at once. Why is that ?

First, processes are meant to support informed decisions. If problem spaces and solution paths cannot be settled upfront they must be done progressively. And that will clearly introduce informational dependencies supporting:

Decisions about what is to be done: alternative paths and their priorities
Decisions about how it should be done: supported features and their priorities
Decisions about how it can be done: quality assurance and acceptance.

In that context the objective of development processes is to do as much of definition, building, and acceptance, and to delay decisions in order to gather the most of the relevant information until the “last responsible moment”, i.e without preempting any of the initial set of alternative options.

Assuming informed decisions are supported by architecture knowledge, processes must take into account engineering constraints regarding:

Technical dependencies associated to the nature of development flows and environments.
Functional dependencies associated to products functionalities and supporting systems.
Organizational dependencies associated to business units and localization.

While those dependencies are defined within architecture layers, their impact on the organization of work units may have to be consolidated when projects are carried out across layers.

Schedules: Running for Time

Whether development cycles stay within or run across architecture layers, there will be no way to decide about deliveries and schedules at project inception. In other words dependencies will have to be sorted out and planning settled along the road.

Project planning means consolidating overlapping time-frames. That may not be a problem for projects set within single architecture layers (e.g migration), but that should definitively be taken into account when heterogeneous time-frames govern changes across architecture layers. With regard to changes managed at project level (endogenous events), the consolidation may be done within project time-frame; but that will not be possible for changes occurring in non managed environments (exogenous events).

Those events are set in time-frames governed by their own rationale (e.g business, organization, or technology) that cannot be subsumed into the engineering timetable:

At enterprise level, time is set by business context. Both business objectives and business process solutions are meant to be decided with regard to actual (aka exogenous) business opportunities (a).
At system level, time is set by project planning (endogenous events). Given functional requirements (e.g users’ stories or use cases), architects and designers have to decide about the scheduling of systems functionalities and services, and the release of corresponding applications. Since those decisions are not directly exposed to exogenous events, they can be made according to engineering constraints and resources availability (b).
At platform level, time is set by business and operational objectives (endogenous events), and technical contexts (exogenous events). Assuming that risks are evenly set, the problem is to align endogenous (managed by project) with exogenous (anticipated from contexts) events: too early releases may preclude later but more useful ones; too late releases may hamper operations (c).

The texture of time differs across architecture layers (yellow for endogenous, red for exogenous)

Whereas those time-scales are to be synchronized, there is no reason they would be congruent. Hence the need of some mechanism, static (e.g milestones) or dynamic (e.g backlogs) supporting the scheduling of work units.

From Milestones to Backlogs

As considered elsewhere, phased models of development may offer some benefits when dependencies originate from different environments or involve different authorities; yet they may impose still bigger penalties when requirements cannot be fully settled upfront. Conversely, agile approaches are the option of choice when complex problem spaces and solution paths are to be explored and refined progressively; but may prove ineffective in dealing with business, organizational, or technical dependencies set from outside projects. That difference of perspective is reflected by the mechanisms used to manage dependencies: milestones or backlogs.

Sorting out dependencies means consolidating informational and engineering constraints across architecture layers. When problem spaces and solution paths cannot be managed under the same authority (heterogeneous dependencies) phased development models use milestones to consolidate expectations and commitments across layers and time-frames.

Otherwise (homogeneous dependencies) agile development models use backlogs to explore problem spaces and solution paths, whatever the architecture layer and nature of dependencies. With the benefit of shared ownership, business events are propagated all along development paths, governing backlogs of stories (business requirements), features (engineering constraints), and releases (operational requirements).

Development processes must consolidate organizational, functional, and technical dependencies. — Backlogs can be used to consolidate organizational, functional, and technical dependencies.

Along that perspective backlogs and milestones can be seen as mirrored solutions of the same problem, namely how to deal with the functional and timing dimension of dependencies: backlogs deal only with the functional dimension as they consider the dependencies between tasks without taking into account their actual timing; milestones look from the opposite direction, anchoring aggregate tasks to timetables before considering dependencies between items. Depending on the point of view:

Backlogs may appear as stacks of stones: the milestones are fragmented and the initial sequence translated into queues.
Milestones may appear as flattened backlogs: dependencies are frozen and stories are ironed out before being merged into heaps.

xxx — Milestones can be seen as “flattened” backlogs, or, alternatively, backlogs as stacked milestones

Hence, with regard to the ranking of dependencies, the difference between backlogs and milestones is of granularity, finer for the former, coarser for the latter. But with regard to execution, the difference is of nature: contrary to milestones, backlogs don’t fix any timing.

That distinction between sequence (functional ranking) and schedule (time ranking) may be critical when iterative development has to be combined with heterogeneous dependencies.

Collaboration Levels

As noted above, the planning of work units must take into account three criteria:

The dependencies between tasks, engineering or informational, determine the sequencing independently of actual timing. They are derived from technical or organizational constraints.
The schedules anchor the start and completion of tasks to time-frames. Some time-frames are set within the enterprise (e.g resources availability), others are set from outside (e.g regulations or business opportunities).
Pace determine the elapsed time taken to complete a task. It may be seen as a metronome used to adjust the throughput depending on resources availability on one hand, quality requirements on the other hand.

At first sight, comparison shows backlogs to outdo milestones on all three accounts: dependencies are managed at finer granularity, which enables dynamic scheduling and releases management; last but not least, due to iteration cycles and time-boxing, development paces can be aligned with resources and quality requirements. Yet, that edge can be misleading if dependencies translate into unmanageable or multiple backlogs.

Collaboration is at the core of iteration cycles, and it can only be achieved through shared and dynamic management of backlogs. Assuming a set of stories, each new cycle has to be preceded by decisions regarding priorities, refinements, and responsibilities; and if informational dependencies have to be taken into account, these decisions must be taken collectively and directly:

Collectively: decisions about priorities and refinements must be negotiated between team members from both sides of the business/system (or users/developers) divide.
Directly: all decisions must be taken by the team itself, without any organizational mediation or external interference.

But those conditions could be thwarted if different projects have to develop stories with shared features implemented on different platforms.

Shared features and cross implementations could thwart collective and direct decision-making.

In that case consolidation mechanisms could bring back fixed scope/schedule configurations:

Different teams, each with its own specific users and developers concerns, will have to commit to agreed features and timetables.
By involving independent organizational units, those decisions will entail some procedural mediation carried out independently of iteration cycles.

Yet, that shouldn’t necessarily be the end of the stories, providing some mechanism could be found to synchronize iteration cycles. And that could be achieved with blackboards.

From Backlogs to Blackboards

Blackboards can be understood as shared backlogs stripped from their ranking mechanism so that items can be consulted and dealt with by different project teams. Alternatively, they can also be seen as timetables stripped from scheduling mechanism. Either way, those views illustrate how blackboards may support shared dependencies without forcing them into time-frames:

Shared features are posted on a single blackboard where their status can be consulted and updated by the teams in charge of the stories concerned.
Development teams post their releases on blackboards according to targeted platforms.

Blackboards are used to manage shared dependencies and differentiated stories’ contents

As it happens, that approach also answers the recurring question of stories’ nature and granularity: with the benefit of blackboards, fine-grained stories can be indexed as business cases, use cases, or new releases and cohabit in backlogs.

Combining backlogs with blackboards provides a collaboration mechanisms supporting external dependencies without impairing teams ownership of iteration cycles. Yet it is not a substitute for schedules as it doesn’t deal with the alignment of cycles with enterprise time-frames.

Time boxes as Pacemakers

Milestones and backlogs are synchronization mechanisms. The former, combined with timetables, coordinate teams along time-spans; the latter, combined with time boxes, coordinate tasks between cycles. Hence, while both aim at the same objective, namely that everything doesn’t happen at once, their understanding of time is very different: timetables are bound to an external measure of time, time boxes are just arbitrarily fixed intervals that can be tethered to any time-frame.

As a consequence, time boxes can be applied at different levels. At system level they are associated to project backlogs and used to set the tempo of iteration cycles. At enterprise level they are associated to business objectives and anchored to strategic plans. Assuming those plans are described by epics, it would be possible to use different tempos depending on level (enterprise or systems) or even applications.

Time boxes can be combined with blackboards to synchronize tempos between enterprise level (T) and interrelated projects (T/x and T/y).

Ideally, differentiated tempos should foster an emerging harmony between melody (users’ stories) and accompaniment (supporting systems) converging into the fulfillment of strategic objectives. Practically, the alignment of releases with epics cannot be taken for granted.

Squaring the Circles: Project Planning

Agile approaches are based upon the dynamic exploration of problem spaces and the iterative development of solution paths, the objective being to maximize the value of functional requirements under the constraints of technical ones. Yet, with spaces and paths defined dynamically, standard exploration procedures like breath or depth-first traversal are useless because the ranking of paths is part of the solution, which means that priorities must be revised at the end of each cycle.

Nonetheless, explorations cannot be everlasting and there must be some end to the story, when stakeholders get what they expect (or accept what they get) and users can begin to reap the benefits. Fixed scope and schedules being ruled out, the problem is to align iterations outcomes (b) with business objectives (a). Solutions can be positioned between two archetypal approaches, one driven by business objectives, the other by development tasks.

ccc — How to align tasks (b) with objectives (a)

The first approach would see development teams take commitments with regard to broadly defined objectives: with problem spaces represented by trees progressively refined and explored, commitments can be made collectively on sets of solution paths within still undefined sub-trees (b1). The team will then take responsibility for the details of iteration cycles and will adjust its throughput as to align releases with business objectives.

Alternatively, and providing a finer granularity can be obtained and managed, stories could be broken down into tasks for which commitments will be made individually by team members (b2). Assuming that the tasks workloads can be assessed, iterations could then be planned and releases scheduled on the basis of time boxes parameters.

Commitments can be made collectively with regard to objectives (b1) or individually with regard to stories (b2). — Commitments can be made collectively with regard to objectives (b1) or individually with regard to tasks (b2).

Not surprisingly, the choice of a planning policy is to be conditioned by the granularity of work units:

Task based planning requires finer grained stories and comes with a phased flavor by reintroducing analysis. That may stretch the intervals between iterations and increase management overheads.
Objective based planning allows for coarser grained stories and is more in line with agile spirit. Yet that may increase the length of iterations and affect their transparency.

All things considered, some feedback loop may be needed when deciding on the size of stories because shorter ones do not necessarily decrease the time to market as they may generate bigger backlogs and exponential overheads in case of complex dependencies.

Balancing Pushes and Pulls: Lean and Just-in-Time Workflows

When push comes to shove project planning turns into conflict management. That may happen with phased development models as well as with agile ones. With the former that will be due to applications forcibly pulled out whatever their value for users and reliability in order to meet unrealistic expectations. With the latter that will be due to requirements forcibly pushed into backlogs disregarding their size and exponential complexity.

The way out of this dilemma is a feedback mechanism between project teams pushing releases and business stakeholders pulling applications. And that is the rationale behind the Kanban development model:

Visualize workflow: up-to-date expectations, constraints, commitments and achievements must be clearly and selectively visible to all concerned. that can be done with backlogs and blackboards.
Limit work in progress: that can be obtained by regulating the selection of solution paths through limits on the size of backlogs and the fragmentation of users’ stories according to their architecture footprint.
Measure and manage flows: metrics and process design can be significantly improved if flows are differentiated depending on architecture layer (business, systems, platforms).
Make process policies explicit: that is already a cornerstone of agile backlog management; those principles should also apply to backboards.
Use models to recognize improvement opportunities: while initially ignored, the benefits of models in agile development is progressively acknowledged. Those benefits have be illustrated in the first part of this article by the use of activity diagrams for the exploration of problems spaces and solutions paths.

Applying those principles will bring about lean processes and just-in-time workflows, improving both users’ value and software quality.

External Links

Kanban Pizza Game

From Stories to Models

Objective

Assuming, for the sake of the argument, that programs are models of implementations, one may also argue that the main challenge of software engineering is to translate requirements into models. But, contrary to programs, nothing can be assumed about requirements apart from being stories told by whoever will need system support for his business process.

Along that reasoning, one may consider the capture and analysis of requirements under the light of two archetypal motifs of storytelling, the Tower of Babel and the Rashomon effect:

While stakeholders and users may express their requirements using their own dialects, supporting applications will have to be developed under the same roof. Hence the need of some lingua franca to communicate with their builders.
A shared language doesn’t necessary mean common understandings; as requirements usually reflect local and time dependent business opportunities and goals, they may relate to different, if not conflicting, aspects of contexts and concerns that will have to be consolidated, eventually.

From such viewpoints, the alignment of system models to business stories clearly depends on languages and narratives discrepancies.

Business to System Analyst: Your language or mine ?

Stories must be told before being written into models, and that distinction coincides with the one between spoken and written languages or, on a broader perspective, between direct (aka performed) and documented communication.

Direct communication (by voice, signs, or mime) is set by time and location and must convey contexts and concerns instantly; that’s what happens when requirements are first expressed by business analysts with regard to actual and specific goals.

kanji_interpret — Direct communication requires instant understanding

Written languages and documented communication introduces a mediation, enabling stories to be detached from their native here and now; that’s what happens with requirements when managed independently of their original contexts and concerns.

kanji_rekap — Documented communication makes room for mediation

The mediation introduced by documented requirements can support two different objectives:

Elicitation: while direct communication calls for instant understanding through a common language, spoken or otherwise, written communication makes room for translation and clarification. As illustrated by Kanji characters, a single written language can support different spoken ones; that would open a communication channel between business and system analysts.
Analysis: since understanding doesn’t mean agreement, mediation is often necessary in order to conciliate, arbitrate or consolidate requirements; for that purpose symbolic representations have to be introduced.

Depending on (1) the languages used to tell the stories and (2) the gamut of concerns behind them, the path from stories to models may be covered in a single step or will have to mark the two steps.

Context and Characters

Direct communication is rooted in actual contexts and points to identified agents, objects or phenomena. Telling a story will therefore begin by introducing characters and objects supposed to retain their identity all along; characters will also be imparted with behavioral capabilities and the concerns supposed to guide them.

ccccc — Stories start with characters and concerns

With regard to business, stories should therefore be introduced by a role, an activity, and a goal.

Every story is supposed be told from a specific point of view within the organization. That should be materialized by a leading role; and even if other participants are involved, the narrative should reflect this leading view.
If a story is to provide a one-lane bridge between past and future business practices, it must focus on a single activity whose contents can be initially overlooked.
Goals are meant to set specific stories within a broader enterprise perspective.

After being anchored to roles and goals, activities will have to be set within boundaries.

Casings and Splits

Once introduced between roles (Who) and goals (Why), activities must be circumscribed with regard to objects (What), actions (How), places (Where) and timing (When). For that purpose the best approach is to use Aristotle’s three unities for drama:

Unity of action: story units must have one main thread of action introduced at the beginning. Subplots, if any, must return to the main plot after completion.
Unity of place: story units must be located into a single physical space where all activities can be carried out without depending on the outcome of activities performed elsewhere.
Unity of time: story units must be governed by a single clock under which all happenings can be organized sequentially.

Stories, especially when expressed vocally, should remain short and, if they have to be divided, splits should not cross units boundaries:

Action: splits are made to coincide with variants set by agents’ decisions or business rules.
Place: splits are made to coincide with variants in physical contexts.
Time: splits are made to coincide with variants in execution constraints.

When stories refer to systems, those constraints should become more specific and coincide with interaction units triggered by a single event from a leading actor.

Filling the blanks

If business contexts, objectives, and roles can be identified with straightforward semantics set at corporate level, meanings become more complex when stories are to be fleshed out with details defined by the different business units. That difficulty can be managed through iterative development that will add specifics to stories within the casing invariants:

Each story is developed within a single iteration whose invariants are defined by its action, place, and time-scale.
Development proceed by increments whose semantics are defined within the scope set by invariants: operations relative to activities, features relative to objects, events relative to time-scales.

A story is fully documented (i.e an iteration is completed) when no more details can be added without breaking the three units rule or affecting its characters (role and goal) or the semantics of features (attributes and operations).

sculptures_Modele — Iterations: a story is fully fleshed out when nothing can be changed without affecting characters’ features or their semantics.

From Documented Stories to Requirements

Stories must be written down before becoming requirements, further documented by text, model, or code:

Text-based documentation uses natural language, usually with hypertext extensions. When analysts are not familiar with modeling languages it is the default option for elicitation and the delivery of comprehensive, unambiguous and consistent requirements.
Models use dedicated languages targeting domains (specific) or systems (generic). They are a necessary option when requirements from different sources are to be consolidated before being developed into code.
Code (aka execution model) use dedicated languages targeting execution environments. It is the option of choice when requirements are self-contained (i.e not contingent to external dependencies) and expressed with formal languages supporting automated translation.

Whatever their form (user stories, use cases, hypertext, etc), documented requirements must come out as a list of detached items with clearly defined dependencies. Depending on dependencies, requirements can be directly translated into design (or implementation) models or will have to be first consolidated into analysis models.

Telling Models from Stories

Putting aside deployment, development models can be regrouped in two categories:

Analysis models describe problems under scrutiny, the objective being to extract relevant aspects.
Design models (including programs) describe solutions artifacts.

sculptures_ad0 — Descriptions and specifications look from different perspectives

Seen from the perspective of requirements, the objective of models is therefore to organize the contents of business stories into relevant and useful information, in other words software engineering knowledge.

Following the principles set by Davis, Shrobe, and Szolovits for Knowledge Management (cf readings), such models should meet two groups of criteria, one with regard to communication, the other with regard to symbolic representation.

As already noted, models are introduced to support communication across organizational structures or intervals of time. That includes communication between business and systems analysts as well as development tools. Those aspects are supposed to be supported by development environments.

As for model contents, the ultimate objective is to describe the symbolic representations of the business objects and processes targeted by requirements:

Surrogates: models must describe the symbolic counterparts of actual objects, events and relationships.
Ontological commitments: models must provide sets of statements about the categories of things that may exist in the domain under consideration.
Fragmentary theory of intelligent reasoning: models must define what artifacts can do or can be done with.

The main challenge of analysis is therefore to map the space between requirements (concrete stories) and models (symbolic representations), and for that purpose traditional storytelling may offer some useful cues.

From Fictions to Functions

Just like storytellers use cliches and figures of speech to attach symbolic meanings to stories, analysts may use patterns to anchor business stories to systems models.

Cliches are mental constructs with meanings set in collective memory. With regard to requirements, the equivalent would be to anchor activities to primitives operations (e.g CRUD), and roles to functional stereotypes.

vvvvv — Archetypes can be used to anchor stories to shared understandings

While the role of cliches is to introduce basic items, figures of speech are used to extend and enrich their meanings through analogy or metonymy:

Analogy is used to identify features or behaviors shared by different stories. That will help to consolidate the description of business objects and activities and points to generalizations.
Metonymy is applied when meanings are set by context. That points to aggregate or composite objects or activities.

Primitives, stereotypes, generalization and composition can be employed to map requirements to functional patterns. Those will provide the building blocks of models and help to bridge the gap between business processes and system functionalities.

External Readings

On Pies & Skies: Abstraction in Models

Objective

The value of a model is its fitness to purpose. Missing this simple truth will inevitably trigger a “flight for abstraction” and begets models devoid of any anchor to business relevancy.

ccc — Abstraction ladders must be propped up by actual contexts (A. Magnaldo)

Yet, that pitfall can be avoided if requirements and models are put in perspective:

Requirements are meant to describe systems in their business context, models describe system artifacts. They should not be confused because the former are supposed to be rooted in concrete descriptions, while the latter aim at their abstract representation.
Models are built from nodes and associations. Nodes refer to instances which are supposed to be uniformly and consistently identified in both business and system contexts; associations may refer to instances (relationships and flows) or classes (specialization and generalization), the former with consistent semantics for business and system realms, the latter with semantics specific to system artifacts.

Along that perspective, the mapping of requirements into models can be achieved by applying selectively the two faces of abstraction: first removing information from the description of actual contexts, then building symbolic representations according to business concerns.

PianoColo — Business Context and Concerns

Starting with requirements, the challenge is therefore to move up and down the abstraction ladder until one gets the focus right, providing a clear and sharp picture of business context and concerns.

Models & Semantics

With regard to systems engineering, models’ semantics are unambiguously determined by their target: business environments or systems artifacts:

Models of business environments describe the relevant features of selected objects and behaviors, including supporting systems. Such models are said extensional as they target subsets of actual contexts.
Models of systems artifacts specify the hardware and software components of supporting systems. Such models are said intensional as they define artifacts to be created.

Business analyst figure maps from territories, software architects create territories from maps — Business analysts figure models from actual contexts and concerns, software architects specify blueprints for artifacts

Climbing up the abstraction ladder, the objective is to align descriptive models of objects and behaviors with prescriptive models of system artifacts. That can be achieved in three steps:

Awareness of contexts: mind the business pie, drop everything else.
Domains of concern: say what features mean.
Symbolic representations: consolidate the descriptions of surrogates.

It is worth to note that the first two levels deal respectively with instances and features of actual objects and activities, while the third deal with artifacts. As a corollary, abstraction at the first two levels should be understood in terms of partitions and subsets, with subtypes introduced only for symbolic representations.

Awareness of Context

As illustrated by sounds (filtering noises) or optics (image point), focusing is a basic perceptual task targeting actual instances of objects, events, or activities. With regard to models, it can be achieved with a pronged move:

Adjust the depth of field to encompass the relevant business context. Large depths of field (aka deep focus) will cover concerns across domains, small ones (aka shallow focus) will support specific business concerns.
Single out image points for identified objects or activities deemed to be pivotal.

abstractLad_1 — Field 1 is too small, field 3 is too large. “Dimensions” has no identity of its own, “Broom” is pointless.

A too shallow focus will capture only some of relevant objects (Piano), activities (Move) or events (Concert). Conversely, extending the focus may go too deep, including irrelevant items (Trumpet, Violinist, Illness, or Repair). Moreover, some image points may depend of others for their identity (Dimensions), or be pointless altogether (Broom).

Domains of Concerns

While business contexts are the same for all, business concerns are by nature specific to domains. The challenge for requirements capture is therefore to anchor specific features to shared objects and activities whose identities are set by business context.

For that purpose concerns are to be organized into domains responsible for the identification of anchors (objects, agents, activities) and the semantics of features:

Shared domains deal with anchors whose continuity and consistency have to be managed across domains, independently of activities.
Specific domains deal with anchors whose continuity and consistency can be managed within a single domain.

At this stage the challenge is to distinguish between identified instances of business objects (piano, concert) and processes (cleaning, moving, playing) on one hand, and the description of roles (mover, cleaner, pianist) and business logic (clean, move, play) on the other hand .

abstractLad_2 — Domains of Concerns and Business Processes

It must be reminded that such models are still at ground level as they describe sets of instances; yet, they can also be seen as the first step up the abstraction ladder, as their objective is to extract relevant features and overlook others.

Symbolic Representations

While business concerns are partial and biased, the symbolic representations managed at system level must be comprehensive and consistent; that’s the objective of requirements analysis.

To start with, symbolic representations are introduced for each set of objects, roles or activities:

Objects surrogates: used to manage the continuity and consistency of business objects independently of business processes (piano, concert).
Process surrogates: used to manage the continuity and consistency of business operations independently of business objects (move, play, clean).
Roles: used to manage the interactions between actual agents and system functionalities (mover, cleaner, pianist). When the continuity and consistency of operations performed by agents are managed (e.g pianist), roles must be associated to surrogates.
Activities: used to describe business logic (move, play, clean).

abstractLad_3 — Business logic and surrogates (#) for objects, processes and pianist .

Those are “flat” descriptions representing ground level instances. In order to be effectively supported by systems, models may have to be expanded downward by specialization, or upward by generalization.

Levels of Abstraction

As already noted, specialization and generalization are not symmetric because, contrary to the former operation, the latter one does modify the semantics of existing artifacts.

The purpose of specialization is to introduce specific descriptions for subsets of instances or features. For instance, assuming requirements are about moving pianos, the representation must climb one step down the abstraction ladder, from concerts to concerts with pianos:

Solo piano concerts are a subset of concerts subject to the same identification mechanisms and integrity constraints (strong inheritance).
The description of moving operations is not used to manage instances and its specialization is only about features (weak inheritance).

abstractLad_3spe — Climbing down: specialization of features (Move Piano) and surrogates (Solo Concert)

The purpose of generalization is twofold as it may be limited to features (aka aspect generalization) or targets both identification mechanisms and features (aka object generalization).

Aspect generalization introduces a base artifact for the description for shared features. Such base artifact is said to be abstract because its inheritance is limited to features and it cannot support the instantiation of surrogates, specialized artifacts keeping their own identification mechanisms. As a corollary, the level of abstraction is not modified because the model remains anchored to the same sets of instances. For instance (a), some administrative procedures can be defined uniformly for all maintenance operations otherwise described and executed independently.

abstractLad_3gen — Climbing up: generalization of features only (a), and for both features and individuals (b).

That’s not the case with object generalization which redefines the initial sets of surrogates as subsets of newly created super-sets. For instance (b), a cleaning process becomes a maintaining processes without the repair extension. Since maintaining processes can be created as simple cleaning or repairing ones, the model is anchored to different levels of abstraction. And since descriptions should not cross levels, roles must be specialized similarly: maintainers are to be identified as such before being qualified as mechanics, even if their interventions are not managed as such (inheritance of transient identification mechanism).

Getting A Proper Grip

Models are neither true or false and can only be assessed for consistency and effectiveness.

While verification of internal consistency is best achieved by built-in checks supported by modeling tools, validation of external consistency requires human inspection and assessment of alternatives. Yet neither will guarantee models effectiveness.

Hence, assuming that (1) systems are meant to handle surrogates of business objects and processes and, (2) those surrogates are designed from models, it ensues that (3) a litmus test of model effectiveness would be the grip it provides on relevant objects and processes.

abstractLad_grip — A grip on context and concerns

And that can only be achieved by pinning models to concrete and identified business objects and processes. That provides a template for modeling grips: concrete descriptions with primary identification in the middle, abstract ones above, aspects or concrete descriptions with inherited identification below.

Reinventing The Wheel

Creativity and Software.

Engineering is all about purposeful and effective design, Art will know nothing of that. Yet, software being made of symbolic constructs, creativity is undoubtedly a core constituent of its design, and beauty a sure sign of its quality.

duchamps_lui2 — Marcel Duchamps: from Artifact to Work of Art

Engineering is about the making of artifacts, software engineering about the making of symbolic ones. Assuming (for the sake of the argument…) a complete and consistent set of requirements with a given lifespan, engineering processes mix reuse of existing artifacts or procedures with the creation of new ones, making room for innovation and creativity.

With regard to software engineering the cases and economics of reuse can be judged according reasoned arguments, but what about innovation ?

Innovation vs Invention

As far as engineering is concerned, innovation is bounded by the achievements of science and technology:

Science builds symbolic representations (aka models) of the world as well as the artifacts needed to check their validity.
Technology considers how to build artifacts, eventually (but not necessarily) based upon scientific models.
Engineering considers how to efficiently build artifacts under given economic conditions.

Engineering of artifacts usually encompasses two basic phases, design and production, the outcome of the former being a set of descriptions, the outcome of the latter batches of products. In that context, innovation may apply to new descriptions (e.g the design of a new weapon or a new recipe), or new modus operandi (e.g the sequencing of tasks).

Reinvent_Manufs — Blueprints mark the difference between Craft and Engineering

As illustrated by cooking recipes, designs and modus operandi (MO) are not necessarily supported by symbolic descriptions like blueprints or flowcharts; as it happens, that difference may mark the boundary between craft and engineering, the former based on individual skills and personal transmission, the latter a collective endeavor supported by disembodied documentation.
That distinction may also be used to distinguish between innovation and invention, the former possibly (but not necessarily) a matter of craft passed on through imitation, the latter a collective achievement necessarily supported by symbolic descriptions.

Circle, Wheel, Loops

Invention is not easily defined, as demonstrated by the different ways intellectual property rights, and especially patents, are managed across countries. To begin with, two principles are widely agreed upon:

Patents are formal descriptions and therefore belong to the realm of symbolic representations.
Patents are not rights to use what is described but rights to exclude others from using those descriptions.

Then, policies differ about patentable subject matter, especially with regard to tangible artifacts (a) as opposed to intangibles like business (b) and computation (c) methods. In other words consensus break down when symbolic descriptions without actual counterparts are considered, which is the case for software.

Even if engineering is circumscribed to the making of artifacts, and business methods are excluded, the problem remains for computation methods when incorporated as software artifacts. In that case symbolic descriptions and actual outcomes are merged into source programs and the distinction between design and production is rubbed out. As a corollary, invention, which was previously associated to the design of actual artifacts, is now deprived of actual context and can only be assessed within its symbolic realm.

But dematerialized inventions are not patent matter, as can be seen with loops: on one hand, with trustworthy predefined language constructs widely available, it doesn’t make sense to “invent” new ways to program iterations; on the other hand patenting those constructs would force designers into squaring circles. More generally, patenting business or computation iterations as inventions would cast a shadow on an uncountable set of activities.

Invent_Patents — Patent restrictions: manufacturing process (a) vs methods (b).

The answer to this conundrum is the distinction between invention and problem solving, the former to be dealt with by engineering, the latter by design.

Engineering & Design

As far as software engineering is concerned, creativity may target two kinds of problems: enterprise organization and applications development.

Given business processes set by objectives and business rules, the problem is to describe how they will be supported by systems functionalities. Since solutions include the definition of features and use of actual devices they can be seen as patentable subject matter.

That’s not the case when systems functionalities are given and the problem is to design the system components that will support them. Solutions will only deal with the design of software component without affecting external features and use of actual ones.

Invent_PbsSols — Solving Organizational and Technical Problems

In both cases, creativity can play in two directions: finding specific solutions to specific problems within the given architectural context; or improving functional or technical architectures. While specific solutions, supposedly not reusable, cannot be considered as inventions, that’s not the case for innovations targeting organizations or systems architectures. Yet, since architectural constructs can also be regarded as solutions to problems, innovations might therefore target architectures capabilities as well as their use.

Know_PbsSols — Finding solutions (+) in architectural contexts (=), with feedback (/+).

At enterprise level problems are set by business contexts and objectives, and solutions based upon enterprise capabilities: who, what, how, where, when. Innovation can only be assessed in terms of business value.
At system level problems are set by organization and solutions supported by systems functionalities: access, persistency, computation, communication, synchronization, etc. New applications can be supported by existing functional architecture or entail innovations which should be assessed in terms of functional metrics and Quality of Service.
At component level problems are set by functional requirements and solutions implemented by components design: server, boundaries, storage, middle ware, embedded units, etc. New developments can be realized using existing components, or entail changes in technical architecture which should be assessed in terms of total cost of acquisition and ownership.

At each level, creativity must remain a balancing act between architectural constraints and innovative solutions.

Enterprise Architectures & Separation of Concerns

Systems are more than Software

As long as information was just data files and systems just computers, the respective roles of enterprise and IT architectures could be overlooked; but that has become a hazardous neglect with distributed systems pervading every corner of enterprises, monitoring every motion, and sending axons and dendrites all around to colonize environments.

Enterprise Governance and Separation of Concerns (R.Magritte)

Yet, the overlapping of enterprise and systems footprints doesn’t mean they should be merged, as a matter of fact, that’s the opposite. When the divide between business and technology concerns was clearly set, casual governance was of no consequence; now that turfs are more and more entwined, dedicated policies are required lest decisions be blurred and entropy escalates as a consequence. The need of better focus is best illustrated by the sundry meanings given to “system”, from computers running software to enterprises running businesses, and even school of thought.

Concerns in Perspectives

As far as enterprises are concerned, systems combine human beings, devices, and software components.

From a functional perspective, their capabilities are best defined by their interactions with their environment as well as between their constituents:

Users are supposed to be actual agents granted with organizational status and responsibilities, and possessing symbolic communication capabilities.
Software components and actual devices cannot be granted with organizational status or responsibilities; the former come with symbolic communication capabilities, the latter without.

Assuming that interactions are governed by information, the objective is to understand the contribution of each type of component with regard to information processing and decision-making.

Catap_AgtsDevSyst — System = Agents + Devices + Symbolic representations

From an engineering perspective, the building of systems is all too often reduced to the development of their software constituents. As a consequence, the complexity of the forest is masked by the singularity of the trees:

The business value of applications is assessed locally instead of being driven by enterprise objectives and organizational constructs.
System models are confused with the programs used to produce software components.
Requirements life cycle, governed by the time-span of business contexts and objectives, is confused with the cycles of reuse of architecture assets.

Since engineering agenda are supposed to support business objectives, their decision-making processes must be aligned yet managed independently. That reasoning also applies to services management whose role is to adjust resources and software releases to operational needs.

Enterprise architectures can then be described as a cross between architecture assets (business objects, organization, technical architecture) on one hand, core processes for business, engineering and services management on the other hand.

Knowa_Processes — EA Artifacts at crossroads between Architectures and Activities

Information is to provide the glue between architecture assets and supported processes.

Information and Architectures Levels

As understood by Cybernetics (see Stafford Beer, “Diagnosing the System for Organizations“), enterprises are viable systems whose success depends on their capacity to countermand entropy, i.e the progressive downgrading of the information used to govern interactions between systems and their environment. And that put knowledge management at the core of systems capabilities.

Knowledge is best defined as information put to use, with information obtained by adding references and sense to data. That blueprint is supposed to be repeated at all architecture levels:

At enterprise level facts pertaining to the conduct of business are captured from environments before being organized into information meant to support enterprise governance.
System level deals with symbolic descriptions of functionalities (information). At this level data is irrelevant, the objective being the consolidation and reuse of shared representations and patterns (knowledge).
The technical level is in charge of operational governance: software components, platforms capabilities, technical resources, communication mechanisms, etc. On one hand contexts are to be monitored and data translated into information; one the other hand operational decisions have to be made (knowledge) and executed which means information translated into data.

Know_EA_Layers — Architecture Layers and Processing Capabilities

If architecture levels can be characterized by processing capabilities, their engineering must be aligned to the corresponding objectives and time frames.

System Engineering and Separation of Concerns

As demonstrated time and again by blame games around projects failures, enterprise and technical concerns are poor engineering bedfellows, and with good reasons: different contexts, concerns, skills, and time scales. Faced with the challenge of bringing enterprise and development perspectives under a single governance, engineering approaches generally follow one of two basic options:

Phased projects (P) give precedence to software development, with requirements supposed to be set at inception and acceptance performed at completion.
Agile projects (A) give precedence to business requirements, with development iterations combining specifications, programming, and acceptance.

Know_EA_Agi_Pha — Phased (P) and Agile (A) development models

While each approach has its merits, agile for complex but well circumscribed projects, phased for large projects with external organizational dependencies, the difficulties each may encounter point to the crux of the matter, namely the separation of concerns between business goals and information technology, bypassed by agile approaches and misplaced by phased ones:

Agile development models are driven by users’ value and based on the implicit assumption that business and technology concerns can be dealt with continuously and simultaneously. That may be difficult when external dependencies cannot be avoided and shared ownership cannot be guaranteed.
Phased development models take a mirror position by assuming that business concerns can be settled upfront, which is clearly a very hazardous policy.

Those pitfalls may be overcome if engineering processes take into account the distinction between knowledge management on one hand, software development on the other hand.

Knowledge management (KM) encompasses all information pertaining to the conduct of business: environment, markets, objectives, organization, and projects. With regard to engineering projects, its role is to define and consolidate the descriptions of symbolic representations to be supported by information systems.
Software development (SD) starts with symbolic descriptions and proceeds with the definition, building and acceptance of the corresponding software artifacts.
Service management (SM) provides the bridge between engineering and operational processes.

Capture of information from data and legacy code can also be achieved respectively by data mining and reverse engineering.

Know_EA_KM_SD — System Engineering = Knowledge (KM) + Software (SD) + Service (SM)

Depending on organizational or technical dependencies, knowledge management and software development will be carried out within integrated development cycles (agile processes), or will have to be phased in order to consolidate the different concerns.

That engineering distinction neatly coincides with the functional divide of architectures: knowledge management supporting enterprise architecture, software development supporting system architecture.

Architectures and Engineering Processes

Business processes are governed by collective representations mixing goals, models and rules, not necessarily formally defined, and subject to change with opportunities. Engineering processes for their part have to be materialized through work units, models, and products, all of them explicitly defined, with limited room for change, and set along constraining schedules. Given that systems’ fate hangs on the hing between business and engineering concerns, the corresponding perspectives must be properly aligned.

That can be achieved if workshops are associated with architecture levels, and work units defined according model layers and development flows:

Knowledge management takes charge of symbolic descriptions pertaining to enterprise concerns. Its objective is to map business and operational requirements with the functionalities of supporting systems. Expressed in MDA parlance, the former would be described by computation independent models (CIMs), the latter by platform independent models (PIMs).
Software development deals with software artifacts. That encompasses the consolidation of symbolic descriptions into functional architectures, the design of software components according to platforms specificity (PSMs), and the production of code according to deployment targets (DPMs).
IT Service Management is the counterpart of knowledge management for actual operations and resources. Its objective is to synchronize business and development time-frames and align operational requirements with releases and resources.

workshopsTasksEA — Knowledge Management (KM), Software Development (SD), Services Management (SM)

That congruence between architecture divides (enterprise, systems, technology), models layers (CIMs, PIMs, PSMs, DPMs), and engineering concerns (facts or legacy, information, knowledge), provides a reasoned and comprehensive framework for enterprise architectures.

Architecture Capabilities & Separation of Concerns

Architectures describe stocks of shared assets, processes describe flows of changes. Given a hierarchized description of architectures, the objective is to ensure the traceability of concerns and decisions across levels and processes.

The first step is to anchor requirements to architecture capabilities:

Who: enterprise roles, system users, platform entry points.
What: business objects, symbolic representations, objects implementation.
How: business logic, system applications, software components.
When: processes synchronization, communication architecture, communication mechanisms.
Where: business sites, systems locations, platform resources.

The rationale of objectives and decisions (the “Why” of Zachman framework) is expressed by dependency links according to the nature of primary factors:

Deontic dependencies are set by external factors, e.g regulatory context, communication technologies, or legacy systems.
Alethic (aka modal) dependencies are set by internal policies, based on the assessment of options regarding objectives as well as solutions.

Capabs_Arch_Procs — Architecture Capabilities and Processes, with deontic (basic) and alethic (dashed) dependencies.

This distinction between dependencies is critical for decision-making and consequently for enterprise governance. Set within time-frames and decorated with time related features, those dependencies can then be consolidated into differentiated strategies for business, engineering and operational processes.

Given that dependencies are usually interwoven, governance must be aligned with the footprints of associated decisions:

Assets: shared decisions affecting different business processes (organization), applications (services), or platforms (purchased software packages).
Users’ Value: streamlined decisions governed by well identified business units providing for straight dependencies from enterprise (business requirements), to systems (functional requirements) and platforms (users’ entry points).
Non functional: shared decisions about scale and performances affecting users’ experience (organization), engineering (technical requirements), or resources (operational requirements).

Know_EA_Groupcam — Separation of Concerns and Requirements Taxonomy

That classification can be used to choose a development model:

Agile approaches should be the option of choice for requirements neatly anchored to users’ value.
Phased approaches should be preferred for projects targeting shared assets across architecture levels. When shared assets are within the same level epic-like variants of agile may also be considered.

Architectures, Processes, and Governance

While there is some consensus about the scope and concerns of Enterprise Architecture as a discipline, some debate remains about the relationship between enterprise and IT governance.

Beyond turf quarrels, arguments are essentially rooted in the distinction between information and supporting systems or, more generally, between organization and IT.

To some extent, those arguments can be ironed out if governance were set with regard to scope, actual or symbolic:

Actual scope deals with current or planned business objects, assets, and processes.
Symbolic scope deals with the design of the corresponding software components.

EA_emerg0 — What is to be governed: actual and symbolic scopes

That distinction matches the divide between enterprise and systems architectures: one set of models deals with enterprise objectives, assets, and organization, the other one deals with system components.

With regard to processes, governance should distinguish between business and engineering:

Business processes are clearly designed at enterprise level, both for their organization and the symbolic description of system representations.
Software engineering ones are under the responsibility of IT governance, from system and software architecture to release and deployment.

EmergA_PvsA — Process and architecture perspectives for Governance

While governance could be shared, there is no reason to assume immediate and continuous alignment of perspectives; that could only be achieved through architecture perspective:

Actual architectures encompass business organization (locations, agents, devices) and systems deployments.
Symbolic architectures include systems functionalities and software development.

And, as a mirror achievement, processes take charge of transitions between actual and symbolic architectures:

EmergA_GAP — Processes carry out Architectures alignment (Pb,Pe), Architectures support Processes consistency (As, Ap).

Symbolic architectures provide the mediation between business requirements and software development (As).
Physical architectures do the same between software development and services management (Ap).
Business processes take responsibility for the mapping of enterprise architecture into symbolic representations (Pb).
Engineering processes do the same for the alignment of software and deployment architectures (Pe).

Enterprise and IT governance can then be defined in terms of Knowledge management, with engineering and business processes gathering data from their respective realms, sharing the information through architectures, and putting it to use according their respective concerns.

External Links

A Historical Look at Enterprise Architecture with John Zachman
Sowa John F., John A. Zachman, “Extending and formalizing the framework for information systems architecture”
Enterprise Architecture Explorations

Architectures of Knowledge

“Nothing that is worth knowing can be taught”

Oscar Wilde

Objective

As illustrated by he Symbolic Systems Program (SSP) at Stanford University, advances in computing and communication technologies bring information and knowledge systems under a single functional roof, namely the processing of symbolic representations.

doisneau_exam — Information and Knowledge: Acquisition, Use and Reuse (R. Doisneau)

Within that understanding one will expect Knowledge Management to shadow systems architectures and concerns: business contexts and objectives, enterprise organization and operations, systems functionalities and technologies. On the other hand, knowledge being by nature a shared resource of reusable assets, its organization should support the needs of its different users independently of the origin and nature of information. Knowledge Management should therefore bind knowledge of architectures with architecture of knowledge.

Knowledge Representation

In their pivotal article Davis, Shrobe, and Szolovits set five principles for knowledge representation:

Surrogate: KR provides a symbolic counterpart of actual objects, events and relationships.
Ontological commitments: a KR is a set of statements about the categories of things that may exist in the domain under consideration.
Fragmentary theory of intelligent reasoning: a KR is a model of what the things can do or can be done with.
Medium for efficient computation: making knowledge understandable by computers is a necessary step for any learning curve.
Medium for human expression: one the KR prerequisite is to improve the communication between specific domain experts on one hand, generic knowledge managers on the other hand.

Representation_Mutilation — Surrogates without Ontological Commitment

That puts information systems as a special case of knowledge ones, as they fulfill the five principles, yet with a functional qualification:
Like knowledge systems, information systems manage symbolic representations of external objects, events or activities purported to be relevant.
System models are assertions regarding legitimate business objects and operations.
Likewise, information systems are meant to support efficient computation and user-friendly interactions.

The only difference is about coupling: contrary to knowledge systems, information and control ones play a role in their context, and operations on surrogates are not neutral.

Knowledge Archeology

Knowledge constructs are empty boxes that must be properly filled with facts. But facts are not given but must be observed, which necessarily entails some observer, set on task if not with vested interests, and some apparatus, natural or made on purpose. And if they are to be recorded, even “pure” facts observed through the naked eyes of innocent children will have to be translated into some symbolic representation. Taking wind as an example, wind socks support immediate observation of facts, free of any symbolic meaning. In order to make sense of their behaviors, wanes and anemometers are necessary, respectively for azimuth and speed; but that also requires symbolic frameworks for directions and metrics. Finally, knowledge about the risks of strong winds can be added when such risks must be considered.

windMonit — Fact, Information, Knowledge

As far as enterprises are concerned, knowledge boxes are to be filled with facts about their business context and processes, organization and applications, and technical platforms. Some of them will be produced internally, others obtained from external sources, but all should be managed independently of specific purposes. Whatever their nature (business, organization or systems), information produced by the enterprises themselves is, from inception, ready to use, i.e organized around identified objects or processes, with defined structures and semantics. That’s not necessarily the case with data reflecting external contexts (markets, regulations, technology, etc) which must be mapped to enterprise concerns and objectives before being of any use. That translation of data into information may be done immediately by mapping data semantics to identified objects and processes; it may also be delayed, with rough data managed as such until being used at a later stage to build information.

From Data to Information

Information is meaningful, data is not. Even “facts” are not manna from heaven but have to be shaped from phenomena into data and then information, as epitomized by binary, fragmented, or “big” data.

Binary data are direct recording of physical phenomena, e.g sounds or images; even when indexed with key words they remain useless until associated, as non symbolic features, to identified objects or activities.
Contrary to binary data, fragmented data comes in symbolic guise, but as floating nuggets with sub-level granularity; and like their binary cousin, those fine-grained descriptions are meaningless until attached to identified objects or activities.
“Big” data is usually understood in terms of scalability, as it refers to lumps too large to be processed individually. It can also be defined as a generalization of fragmented data, with identified targets regrouped into more meaningful aggregates, moving the targeted granularity up the scale to some “overwhelming” level.

Since knowledge can only be built from symbolic descriptions, data must be first translated into information made of identified and structured units with associated semantics. Faced with “rough” (aka unprocessed) data, knowledge managers can choose between two policies: information can be “mined” from data using statistical means, or the information stage simply bypassed and data directly used (aka interpreted) by “knowledgeable” agents according to their context and concerns.

joli-polymorphisme — Non symbolic data can be interpreted by “knowledgeable” agents according to their concerns.

As a matter of fact, both policies rely on knowledgeable agents, the question being who are the “miners” and what they should know. Theoretically, miners could be fully automated tools able to extract patterns of relevant information from rough data without any prior information; practically, such tools will have to be fed with some prior “intelligence” regarding what should be looked for, e.g samples for neuronal networks, or variables for statistical regression. Hence the need of some kind of formats, blueprints or templates that will help to frame rough data into information.

Information Properties

Knowledge must be built from accurate and up-to-date information regarding external and internal state of affairs, and for that purpose information items must be managed according to their source, nature, life-cycle, and relevancy:

Source: Government and administrations, NGO, corporate media, social media, enterprises, systems, etc.
Nature: events, decisions, data, opinions, assessments, etc.
Type of anchor: individual, institution, time, space, etc.
Life-cycle: instant, time-related, final.
Relevancy: traceability with regards to business objectives, business operations, organization and systems management.

Knowa_canon — Information must be timely, understandable, and relevant

On that basis, knowledge management will have to map knowledge to its information footprint in terms of reliability (source, accuracy, consistency, obsolescence, etc) and risks.

From Information to Knowledge

Information is meaningful, knowledge is also useful. As information models, knowledge representations must first be anchored to persistency and execution units in order to support the consistency and continuity of surrogates identities (principle #1). Those anchors are to be assigned to domains managed by single organizational units in charge of ontological commitments, and enriched with structures, features, and associations (principle #2). Depending on their scope, structure or feature, semantics are to be managed respectively by persistent or application domains. Likewise, ontologies may target objects or aspects, the former being associated with structural sub-types, the latter with functional ones. Differences between information models and knowledge representation appear with rules and constraints. While the objective of information and control systems is to manage business objects and activities, the purpose of knowledge systems is to manage symbolic contents independently of their actual counterparts (principle #3). Standard rules used in system modelling describe allowed operations on objects, activities and associated information; they can be expressed forward or backward:

Forward (aka push) rules are conditions on when and how operations are to be performed.
Backward (aka pull) rules are constraints on the consistency of symbolic representations or on the execution of operations.

Assuming a continuity between information and knowledge representations, the inflection point would be marked by the introduction of modalities used to qualified truth values, e.g according temporal and fuzzy logic:

Temporal extensions will put time stamps on truth values of information.
Fuzzy logic put confidence levels on truth values of information.

That is where knowledge systems depart from information and control ones as they introduce a new theory of intelligent reasoning, one based upon the fluidity and volatility of knowledge.

Meanings are in the Hands of Beholders

Seen in a corporate context, knowledge can be understood as information framed by contexts and driven by purposes: how to run a business, how to develop applications, how to manage systems. Hence the dual perspective: on one hand information is governed by enterprise concerns, systems functionalities, and platforms technology; on the other hand knowledge is driven by business processes, systems engineering, and services management.

Knowa_Archis — Knowledge of Architectures, Architecture of Knowledge.

That provides a clear and comprehensive taxonomy of artifacts, to be used to build knowledge from lower layers of information and data:

Business analysts have to know about business domains and activities, organization and applications, and quality of service.
System engineers have to know about projects, systems functionalities and platform implementations.
System managers have to know about locations and operations, services, and platform deployments.

The dual perspective also points to the dynamics of knowledge, with information being pushed by the their sources, and knowledge being pulled by their users.

A Time for Every Purpose

As understood by Cybernetics, enterprises are viable systems whose success depends on their capacity to countermand entropy, i.e the progressive downgrading of the information used to govern interactions both within the organization itself and with its environment. Compared to architecture knowledge, which is organized according to information contents, knowledge architecture is organized according to functional concerns and information lifespan, and its objective is to keep internal and external information in synch:

Planning of business objectives and requirements (internal) relative to markets evolutions and opportunities (external).
Assessment of organizational units and procedures (internal) in line with regulatory and contractual environments (external).
Monitoring of operations and projects (internal) together with sales and supply chains (external).

Knowa_DecisLevels2 — Knowledge Architecture and Shearing Layers: strategy at leisure, time for plans, real-time operations.

That put meanings (that would be knowledge) in the hands of decision makers, respectively for corporate strategy, organization, and operations. Moreover, enterprises being living entities, lifespan and functional sustainability are meant to coalesce into consistent and homogenous layers:

Enterprise (aka business, aka strategic) time-scales are defined by environments, objectives, and investment decisions.
Organization (aka functional) time-scales are set by availability, versatility, and adaptability of resources
Operational time-scales are determined by process features and constraints.

Such a congruence of time-scales, architectures and purposes into Shearing Layers is arguably a key success factor of Knowledge management.

Search and Stretch

As already noted, knowledge is driven by purposes, and purposes, not being confined to domains or preserves, are bound to stretch knowledge across business contexts and organizational boundaries. That can be achieved through search, logic, and classification.

Searches collect the information relevant to users concerns (1). That may satisfy all the knowledge needs, or provide a backbone for further extension.
Searches can be combined with ontologies (aka classifications) that put the same information under new lights (1b).
Truth-preserving operations using mathematics or formal languages can be applied to produce derived information (2).
Finally, new information with reduced confidence levels can be produced through statistical processing (3,4).

For instance, observed traffic at toll roads (1) is used for accounting purposes (2), to forecast traffic evolution (3), to analyze seasonal trends (1b) and simulate seasonal and variable tolls (4).

Knowa_Stretch — Observed facts (1), deductions (2), projections (3), transposition (1b) and hypothesis (4).

Those operations entail clear consequences for knowledge management: As far as computational distances don’t affect confidence levels, truth-preserving operations are neutral with regard to KM. Classifications are symbolic tools designed on purpose; as a consequence all knowledge associated to a classification should remain under the responsibility of its designer. Challenges arise when confidence levels are affected, either directly or through obsolescence. And since decision-making is essentially about risks management, dealing with partial or unreliable information cannot be avoided. Hence the importance of managing knowledge along shearing layers, each with its own information life-cycle, confidence requirements, and decision-making rules.

From Knowledge Architecture to Architecture Capability

Knowledge architecture is the corporate central nervous system, and as such it plays a primary role in the support of operational and managerial processes. That point is partially addressed by Frameworks like Zachman whose matrix organizes Information System Architecture (ISA) along capabilities and design levels. Yet, as illustrated by the design levels, the focus remains on information technology without explicitly addressing the distinction between enterprise, systems, and platforms.

Capabilities can be defined across architecture layers with regard to business, engineering, and operational processes

That distinction is pivotal because it governs the distinction between corresponding processes, namely business processes, systems engineering, and services managements. And once the distinction is properly established knowledge architecture can be aligned with processes assessment.

Yet that will not be enough now that digital environments are invading enterprise systems, blurring the distinction between managed information assets and the continuous flows of big data.

DataMining_Capabs — The outer range anchors enterprise architecture and objectives to business environments

That puts the focus on two structural flaws of enterprise architectures:

The confusion between data, information, and knowledge.
The intrinsic discrepancy between systems and knowledge architectures.

Both can be overcame by merging system and knowledge architectures applying the Pagoda blueprint:

The alignment of platforms, systems functionalities, and enterprise organization respectively with data (environments), information (symbolic representations), and knowledge (business intelligence) would greatly enhance the traceability of transformations induced by the immersion of enterprises in digital environments.

Knowledge Representation & Profiled Ontologies

Faced with digital business environments, enterprise must sort relevant and accurate information out of continuous and massive inflows of data. As modeling methods cannot cope with the open range of contexts, concerns, semantics, and formats, looser schemes are needed, that’s precisely what ontologies are meant to do:

Thesaurus: ontologies covering terms and concepts.
Documents: ontologies covering documents with regard to topics.
Business: ontologies of relevant enterprise organization and business objects and activities.
Engineering: symbolic representation of organization and business objects and activities.

Ontologies: Purposes & Targets

Profiled ontologies can then be designed by combining that taxonomy of concerns with contexts, e.g:

Institutional: Regulatory authority, steady, changes subject to established procedures.
Professional: Agreed upon between parties, steady, changes subject to accords.
Corporate: Defined by enterprises, changes subject to internal decision-making.
Social: Defined by usage, volatile, continuous and informal changes.
Personal: Customary, defined by named individuals (e.g research paper).

Last but not least, external (regulatory, businesses, …) and internal (i.e enterprise architecture) ontologies could be integrated, for instance with the Zachman framework:

Ontologies, capabilities (Who,What,How, Where, When), and architectures (enterprise, systems, platforms).

Using profiled ontologies to manage enterprise architecture and corporate knowledge will help to align knowledge management with EA governance by setting apart ontologies defined externally (e.g regulations), from the ones set through decision-making, strategic (e.g plate-form) or tactical (e.g partnerships).

An ontological kernel has been developed as a Proof of Concept using Protégé/OWL 2; a beta version is available for comments on the Stanford/Protégé portal with the link: Caminao Ontological Kernel (CaKe).

From Data Analysis to Deep Learning

Set between all-inclusive onslaught of data on one side, pervasive smart bots on the other side, information systems could lose their identity and purpose. And there is a good reason for that, namely the confusion between data, information, and knowledge.

Knowledge is the ability to make differences

As it happened aeons ago, ontologies have been explicitly though up to deal with that issue.

External Links

UML & Users’ Concerns

Objective

Whereas UML has been brought to existence by very wise men under very propitious skies, the initial enthusiasm and first successes have never been transformed into wider acceptance and customary usage; subsequent updates and extensions didn’t help and may even have triggered some anticlimax. More than fifteen years after its launch, the utilization of UML remains limited, both in breadth (projects developed) and depth (features effectively used). Moreover, the UML house is deeply divided and there isn’t much consensus among the few that use it comprehensively and consistently, principally to support domain specific languages (DSL).

Babel_aDesmet — The Divided House of UML (Anne Desmet)

Certainly, there must have been a wrong turn somewhere, possibly at the UML2 crossing when the OMG committee lost sight of users modeling needs and took the road to meta-models. Considering UML’s shrinking stamp and dwindling relevancy, that road appears more and more like a dead-end; but it may be still possible to get back on track and retrieve the Us of the UML: unified semantics for all and sundry users.

Where to Look

Whether on driving or back seats, respectively for model driven or agile methods, models are widely accepted as a necessary constituent of development processes. Nonetheless, and despite being the only official standard, UML standing appears to falter, up to be already seen as a cold case. As suggested by Ivar Jacobson (“The road ahead for UML“), one of its main drawback would be its lack of modularity with regard of users needs. If that flaw is to be fixed, the question is where to look: directly at language level, or at supporting mechanisms.

Given the broad consensus that surrounded the initial project, one should at first look for a sound and stable subset to be used as a backbone and fleshed out according specific contexts, purposes or users. As a matter of fact that is what stereotypes and profiles are meant to do, except that without a well-defined backbone of unambiguous constructs, the only possible outcomes are domain specific languages. So, one should first consider how the separation of concerns could be better supported by language constructs.

uml_seprconc — Language Constructs, Model, and Separation of Concerns

Separation of Concerns

Despite its roots in the Object Oriented paradigm, UML has demonstrated its adaptability to all and every method or domain. Unfortunately, being a Jack of all trades often means a master to none, and the use of UML is clearly frustrated by its versatility; that translates either into shallow usage of ambiguous semantics, or into extensions targeting specific domains or technologies.

On the ground, three mechanisms can be used to make for the lack of focus: stereotypes, views, and customization.

UML stereotyping mechanism support predefined constructs for problem (business objects and processes) or solution (system architecture and object design) spaces. Stereotypes can be grouped into profiles, e.g for specific business domains or technical architectures.
Views (or perspectives) organize access to models according contents: logical, physical, conceptual, pragmatic, etc
Tool customization organizes access to models according users purposes and skills: analyst, architect, designer, developer, etc.

While those approaches have their benefits, they are set independently of languages constructs, either as UML extensions (stereotypes and profiles), or defined from outside by development methodologies (views) or projects organization (customization). As a consequence, they have little or no effect on the simplicity or efficiency of UML; they may even add to confusion and complexity when overlapping stereotypes are introduced to support multiple taxonomies, e.g technical architectures and business domains.

uml_seprconc3 — Language Constructs (a), Stereotyped Model (b), Combined Views or Profiles (c)

That may point to a clear direction: given the potency of the stereotyping mechanism and its pivotal role in UML utilization, significant benefits could be achieved through a better integration into core language constructs, even if that entails some constraints or limitations. Two straight modifications should be considered:

Model layers: language constructs should be re-organized along architectural concerns for enterprise (business processes), system (functionalities), and platforms (components).
Stereotypes visibility: language constructs should support the distinction between local taxonomies and “unified” ones, the former set with limited scope and visibility, the latter meant to be applies across layers.

While both modifications can be carried out on their own, their benefits would be boosted if they were set within the broader MDA framework and supported by specific language constructs.

Modular Language Constructs

Given the growing intricacy, ubiquity and diversity of systems, UML complexity and versatility should clearly be in demand, and the problem is to harness those capabilities according the needs and skills of the different kinds of users.

That’s arguably a critical flaw of UML, which lumps together essential with secondary constructs, as well as definite with ambivalent semantics. That brings weighty consequences, both for users and models:

Steep or even abrupt learning curve: confronted to a wall of mixed constructs users have to master the whole upfront, whatever their needs and skills.
Blurred concerns: describing various specific contents with the same ambivalent constructs will either distort language semantics, or blur concerns specificities.
Corrupted transformation: whatever the modeling tools, the bad apples of inputs will usually corrupt the whole of outputs. In other words any advance in model driven development requires a sound backbone of unambiguous language constructs.

As noted above, language constructs can be regrouped along two perspectives, one directly associated with users architectural concerns, the other reflecting the scope and visibility of targeted artifacts. While there is no particular reason to match complexity levels with architectural concerns, mapping them to granularity has a clear rationale. Such a “born again” UML would distinguish between two levels of language constructs:

Those pertaining to objects and activities identified by architectures, whatever their nature: enterprise, systems or platforms.
Those used to describe internals of objects and activities independently of their aspects and behaviors at architecture level.

uml_cornot — Model Transformation: lumped (b) vs differentiated (a) language constructs.

That re-configuration would bring modularity to the language, enabling a smooth learning curve. More importantly, a clear-cut separation of concerns will enable some kind of Just-In-Time model transformation: instead of cumulative noises (b), one will get separate transformations for models architectural backbone on one hand, contingent specificities on the other hand (a). And that could be a real game-changer for lean and fit models.

While that could be achieved by different means, a simple solution would be to use the stereotyping mechanism to describe supporting structures of enterprise, functional, and technical architectures.

Transformation vs Portability

Model transformation is about changing contents within the same environment, portability is about moving the same contents across different environments; and despite apparent similarities, they deal with different concerns, set by users for the former, by tools vendors for the latter.

Transformation is normally performed under a single corporate roof according agreed semantics; as a corollary, it is meant to cover the full contents of models. That’s not the case for portability, whose primary objective is the exchange of consolidated contents between heterogeneous environments; while sources and targets may have to share the whole of their models, a sound policy should make room for selective portability of specific or confidential contents.

The Meta-Object Facility (MOF) is the solution of choice for portability. As a meta-language it is used to describe language constructs at source and target environments; mapping rules can then be defined and bridges built between environments. As it is, those bridges usually scale very poorly due to the exponential complexity of rules having to cover all and every model idiosyncrasies; and that’s unfortunate for portability which, instead of focused targets, has to deal with overweight models cluttered with useless contents (b).

uml_porta — Portability between modeling environments: Lumped (b) vs Differentiated (a) constructs.

That situation would be greatly improved (a) if the wheat of consolidated constituents could be separated from the chaff of ambiguous or irrelevant contents. On a broader perspective that will open the way leaner and fitter models.

One step back may put UML back on track

There is something of a consensus among the software engineering community regarding (1) the benefits of models and (2) the failures of UML. As should be expected, that consensus translates into fragmented modeling practices and, more generally, software engineering methodologies. Obviously there isn’t much of a future for UML along that path, but the case is still open and the trend can be reversed by putting users needs back on UML driving seat.

External Links

Interaction Flow Modeling Language

Agile vs Waterfall: Right vs Left Brain ?

Preamble

All too often when the agile project model is discussed, the debate turns into a religious war with waterfall as the villain. But asking which project model will bring salvation will only bring attrition, because the question is not which is the best but when it is the best. It’s like asking if a hammer is a better tool than a sickle !

Instead, one should first try to understand how they stand apart, and deduce from that what they are best for; the comparison between the left and right sides of the brain may provide a good starting point.

B2C: Balancing Brain Capacities

If it is (still) impossible to know what people think, it is possible to know where their thinking is rooted in brains, and the answer is unequivocal:

The left side of the brain is analytical; faced with a problem, it looks for parts and process them in sequence.
The right side of the brain is better at synthesis as it looks at the whole and processes all relevant information simultaneously.

Obviously casts will differ between individuals depending on inborn qualities and developed preferences; moreover, each individual will balance his brain sides according to the task at hand. The same should apply when projects must decide between iterative and procedural approaches.

What a Hand can Hold

When project management is first considered, the Whole vs Parts alternative should be the discriminating factor: since human brains cannot process an unlimited number of elements simultaneously, work units to be handled by teams must be clearly circumscribed, with a number of independent functional units not exceeding a dozen.

That could be a pitfall for agile developments if iterations and increments were to be associated with an exponential growth of complexity. Yet, partitioning a large project into sub-tasks doesn’t necessarily call for a waterfall schema if the sub-tasks can be performed independently.

What the Hand is Told

Sequential processing can be dumb because the intelligence can already be etched in the sequences. That’s not the case if relevant information is to be picked out and processed as a whole; that can only be done with a clear purpose guiding the hand.

Replacing an administrative process by a collaborative one entails some kind of shared ownership, with teams granted full responsibility for decisions, schedules, and quality. Otherwise the different concerns, purposes or authorities, possibly but not necessary at odds, should be set apart as sub-tasks, and milestones introduced for their consolidation.

What is Handed Over

Development projects may handle three kind of artifacts: texts, models, and code, the first and last being mandatory, the second being optional. Since texts and code are best processed sequentially they are handed over to brain left side; conversely, models are meant to combine different perspectives, e.g structures and behaviors, which put them on the right side of the brain.

Curiously, that seems to put agile in some kind of conundrum: despite models being the symbolic representation best suited to holistic processing, agile approaches are partial to code, even if models are not explicitly ruled out. As a matter of fact, agile tenets are more partial to products than to code, and what is handed over and tested against requirements is not meant to be a program but a running application.

Hand in Hand

Just like the two parts of the brain bring their best to shared concerns and purpose, agile and phased schemes should be enlisted according to their respective merits and shortcomings:

Agile is clearly a better option when shared ownership can be secured and milestones and models are not needed.
Phased solutions (“waterfall” is a red-herring) are necessary when organizational, functional or technical dependencies between projects mean that some consolidation cannot be avoided between development process.

Assuming agile methods are used whenever possible, models should provide the glue when external dependencies are to be taken into account:

Organizational dependencies are managed across model layers: business requirements govern system functionalities which govern platforms implementations.
Functional dependencies are managed across architecture tiers: transient non shared components (aka boundaries) are governed by transient shared components (aka controls) which are governed by persistent shared components (aka entities).
Development dependencies should not cross projects limits as they should be managed at domain level using inheritance or delegation.

External Links

Mastering Agile with SHU-HA-RI

Models in Driving Seats

Objective

Model driven software engineering (aka MDA, aka MBSE, aka MDE) has had a great future for quite some time, yet there isn’t much consensus about what that could be and, in particular, about what kind of models should be in the driving seat.

Shadow Cards Envelope.indd — Shadowing Reality

Pending some agreement about model contents (e.g specific ?) and capabilities (e.g executable ?), the driving of software engineering processes will probably remain more practices than principles.

Shadowing Reality

Models are shadows of reality, with their form and contents set by contexts and concerns. They can be characterized by their purpose and capabilities.

Regarding purpose, models fall in two groups: descriptive models deal with problems at hand, prescriptive models with solutions.

Descriptive models are partial and biased representations of actual contexts. Partial because they only deal with relevant objects, activities and features; biased because the selection is made on purpose.
Prescriptive models are complete descriptions of artifacts.

Regarding capabilities the distinction is between intensional and extensional languages:

Extensional (aka denotative) languages deal with sets of identified instances of objects and activities. As they condone partial or ambiguous statements, they are best used for descriptive models.
Intensional (aka connotative) languages deal with the semantics and constraints of symbolic representations. Due to their formal capabilities they are best used for prescriptive models.

Along that reasoning System Models can be characterized along architecture contexts: business processes (enterprise), functionalities (systems), and platform implementations (technologies):

Business models are descriptive and built with extensional languages (business is often said to bloom on discrepancies). They are necessarily partial as they target specific contexts and concerns.
Functional (aka analysis) models are prescriptive and built with intensional languages as they must specify the semantics and constraints of symbolic representations. Yet they are not necessarily complete since they don’t have to cover every details of business processes or implementations (cf traceability).
Implementation models (aka design) are prescriptive with no use for extensional capabilities since the relevant physical objects, i.e extensions, are system components directly derived from system specifications. However, they must support complete and formal descriptions of component features.

handShad_tweety — Business object, analysis and design, implementation.

Models don’t Talk Alone

Models are built with logographic languages that should not be confused with phonetic ones: whereas the latter convey information sequentially, the former build semantics from different sources; that enables models to be read from different perspectives. Contrary to programs whose semantic is bound to a fixed sequential execution, models don’t talk alone, but must be chatted to. Even when their readings are sequential, the sequences are governed by readers, not by models.

That point is pivotal if model transformation, arguably a pillar of model driven development, is to be supported along different perspectives and according different concerns.

Besides, it must be noted that while models can be fully translated into (and reversed from) sequential representations (e.g with XMI), transcripts are just projections and should not be confused with models as such.

Models don’t Walk Alone

Like talks, walks are sequential as they advance step by step. Hence, while some models can be walked (aka executed), such walks are only instances of behaviors supported by models.

That should be especially clear for system models which describe architectures combining agents and devices as well as software components, contrary to programs which are limited to software components structure and sequential (or parallel) execution.

Just like XMI transcripts should not be confused with original models, “executable” models should not be confused with fully fledged ones because they simulate the behaviors of agents and devices as if they were software components. While that may be useful for models targeting software components within a given architecture, ignoring the specificities of software, agents, and devices would be pointless when the objective is to design a system architecture.

Abstraction Levels

Defining models as abstractions may be correct but not very helpful when deciding what kind of abstraction should drive development processes. First, the question is to define how concerns and purposes should be used to define abstractions, in other words to set apart significant from non-significant information. Then, in order to avoid flights for always higher abstractions without burying models into ground details, some principles are needed regarding specialization and generalization.

When systems are considered, abstraction levels are set by enterprise organization, systems functionalities, and platform technologies, with concerns expressed by business, functional, or technical requirements. Given a hierarchy of concerns, models must be set at the proper level of abstraction: below that level part of information will be redundant or irrelevant; above, useful features and classifications may be overlooked as some information will be either wanting or will not discriminate between variants.

Such levels can be identified by selectively applying specialization and generalization to constrained hierarchies:

Inheritance should not cross model layers: hierarchies of business, functional and technical artifacts must be kept separate.
Structures and behaviors pertain to different concerns: abstractions of objects and aspects should be managed independently.
Specialization should be applied when subset of identified objects or behavior are associated with specific features. Generalization should be introduced when models must be consolidated.

Such an approach brings significant benefits for reuse, arguably one of the main objective of abstraction. And that appears clearly when developments are governed by models and architecture components and mechanisms are to be shared across model layers.

Reuse_K2FA3 — Reuse of business and functional models along functional tiers, with abstractions for structures (green) and aspects (orange).

Driving Models and Roadmaps

Systems engineering has to meet three kinds of requirements: business needs, system functionalities, and components implementation. In a perfect world there would be one stakeholder, one architecture, and one time-scale. Unfortunately, projects may involve different stakeholders, target different architectures, and be set along different time-frames. In that case milestones and roadmaps are to be introduced in order to bring all expectations and commitments under a common roof, with models providing the glue between them. That may be achieved with models defined along MDA layers:

Computation Independent Models (CIMs) describe business objects and processes independently of supporting systems.
Platform Independent Models (PIMs) describe how business processes are supported by systems seen as functional black boxes, i.e disregarding the constraints associated to candidate technologies.
Platform Specific Models (PSMs) describe system components as implemented by specific technologies.

Footprints_MDA — From Models to Roadmaps

Interestingly, both extremities of development processes are textual descriptions, informal at the beginning, formal at the end, with models providing bridges in between. As noted above, those bridges are not always necessary: texts can be directly translated into instructions (as illustrated by voice command devices), or project teams with shared ownership can develop programs according users’ requirements (as promoted by Agile methods). Yet, the question should always be asked, and when textual requirements cannot be directly developed into programs the first task should be to draw the shortest modeling path.

Roadmaps and Meta-models

Model driven tools may appear under different guises yet most rely on meta-models and the Meta Object Facility (MOF). Given that meta-models are models of models, they are supposed to focus on a subset of relevant features selected on purpose, which, for driving models, would be some kind of road signs governing models transformation. What that could be? Two approaches are to be considered:

Language translation: as presented by the report of the Dagstuhl Seminar, meta-models can be designed according their generic transformation capabilities and used to single out language constructs in order to transfer model contents into another language.
Separation of concerns: as development advances and models take into account different concerns, meta-models can be used to monitor and control the selective processing of corresponding contents. That could be achieved if transformations were governed by traffic signs singling out relevant features and waving aside the leftovers.

Each option points to a different perspective, the former targeting tools providers, the latter aiming at modellers. Whereas MDA layers (for business, functionalities, and technology) clearly point to models built with the Unified Modeling Language according organizational, functional and technical concerns, most of current implementations follow the language option; while those tools may be (theoretically) open at technical level, they usually rely on domain specific languages. By narrowing functional scopes and relying on automated translation to bridge the gaps, solutions based upon domain specific languages can only provide local solutions to fragmented problems. That road could be a bumpy one for model driven engineering.

Postscript

Thinking again, the “MDA” moniker can be misleading as it may blur the distinction between models and their contents: given that MDA model layers effectively correspond to architecture levels, the pivotal MDA contention is that the modeling of systems is meant to be driven by enterprise architecture divides.

Objective

Architectures and Projects Scope

Mapping Project Scope

Iterative Mapping of Project Footprint

Development Paths: From Users’ Stories to Use Cases

Backlogs and Pathfinders

Squaring the Circles: From Epics to Releases

A Time for Every Purpose: Time-boxes as Pace-Makers

Further Reading

Objective

Dependencies: Playing for Time

Schedules: Running for Time

From Milestones to Backlogs

Collaboration Levels

From Backlogs to Blackboards

Time boxes as Pacemakers

Squaring the Circles: Project Planning

Balancing Pushes and Pulls: Lean and Just-in-Time Workflows

Further Reading

External Links

Objective

Business to System Analyst: Your language or mine ?

Context and Characters

Casings and Splits

Filling the blanks

From Documented Stories to Requirements

Telling Models from Stories

From Fictions to Functions

Further Reading

External Readings

Objective

Awareness of Context

Domains of Concerns

Symbolic Representations

Levels of Abstraction

Getting A Proper Grip

Further Reading

Creativity and Software.

Innovation vs Invention

Circle, Wheel, Loops

Engineering & Design

Further Reading

Systems are more than Software

Concerns in Perspectives

Information and Architectures Levels

System Engineering and Separation of Concerns

Architectures and Engineering Processes

Architecture Capabilities & Separation of Concerns

Architectures, Processes, and Governance

Further Reading

External Links

Objective

Knowledge Representation

Knowledge Archeology

From Data to Information

Information Properties

From Information to Knowledge

Meanings are in the Hands of Beholders

A Time for Every Purpose

Search and Stretch

From Knowledge Architecture to Architecture Capability

Knowledge Representation & Profiled Ontologies

From Data Analysis to Deep Learning

Further Reading

External Links

Objective

Where to Look

Separation of Concerns

Modular Language Constructs

Transformation vs Portability

One step back may put UML back on track

Further Reading

External Links

Preamble

B2C: Balancing Brain Capacities

What a Hand can Hold

What the Hand is Told

What is Handed Over

Hand in Hand

Further Reading