As every artifact, models can be defined by nature and function. With regard to nature, models are symbolic representations, descriptive (categories of actual instances) or prescriptive (blueprints of artifacts). With regard to function, models can be likened to currency, as they serve as means of exchange, instruments of measure, or repository.
Along that understanding, models can be neatly characterized by their intent:
No use of models, direct exchange (barter) can be achieved between business analysts and software engineers.
Models are needed as medium supporting exchange between organizational units with different business or technical concerns.
Models are used to assess contents with regard to size, complexity, quality, …
Models are kept and maintained for subsequent use or reuse.
Depending on organizations, providers and customers could then be identified, as well as modeling languages.
States are used to describe relevant aspects in contexts and how the changes are to affect systems representations and behaviors.
On that account, events and states are complementary: the former are to notify relevant changes, the latter are to represent the partitions (²) that makes these changes relevant. Transitions are used to map the causes and effects of changes.
State of physical objects.
State of processes’ execution.
State of actors’ expectations.
State of symbolic representations.
Beside alignment with events, defining states consistently across objects, processes, and actors is to significantly enhance the traceability and transparency of architectures designs.
Depending on context and purpose requirements can be understood as customary documents, contents, or work in progress.
Given that requirements are the entry point of engineering processes, nothing should be assumed regarding their form (natural, formal, or specific language), or content (business, functional, non-functional, or technical).
Depending on the language used, requirements can be directly analyzed and engineered, or may have to be first formatted (aka captured).
Requirements taxonomy should be set with regard to processes (business or architecture driven) and stakeholders (business units or enterprise architecture).
Depending on content and context, requirements can be engineered as a whole (agile development models), or set apart as to tally with external dependencies (phased development models).
Agile and phased development solutions are meant to solve different problems and therefore differ with artifacts and activities; that can be illustrated by requirements, understood as dialogs for the former, etched statements for the latter.
Ignoring that distinction is to make stories stutter from hiccupped iterations, or phases sputter along ripped milestones.
Agile & Phased Tell Different Stories Differently
As illustrated by ill-famed waterfall, assuming that requirements can be fully set upfront often put projects at the hazards of premature commitments; conversely, giving free rein to expectations could put requirements on collision courses.
That apparent dilemma can generally be worked out by setting apart business outlines from users’ stories, the latter to be scripted and coded on the fly (agile), the former analysed and documented as a basis for further developments (phased). To that end project managers must avoid a double slip:
Mission creep: happens when users’ stories are mixed with business models.
Jump to conclusions: happens when enterprise business cases prevail over the specifics of users’ concerns.
Interestingly, the distinction between purposes (users concerns vs business functions) can be set along one between language semantics (natural vs modeling).
Semantics: Capture vs Analysis
Beyond methodological contexts (agile or phased), a clear distinction should be made between requirements capture (c) and modeling (m): contrary to the former which translates sequential specifications from natural to programming (p) languages without breaking syntactic and semantic continuity, the latter carries out a double translation for dimension (sequence vs layout) and language (natural vs modeling.)
The continuity between natural and programming languages is at the root of the agile development model, enabling users’ stories to be iteratively captured and developed into code without intermediate translations.
That’s not the case with modeling languages, because abstractions introduce a discontinuity. As a corollary, requirements analysis is to require some intermediate models in order to document translations.
The importance of discontinuity can be neatly demonstrated by the use of specialization and generalization in models: the former taking into account new features to characterize occurrences (semantic continuity), the latter consolidating the meaning of features already defined (semantic discontinuity).
As noted above, users’ stories can be continuously developed into code because a semantic continuity can be built between natural and programming languages statements. That necessary condition is not a sufficient one because users’ stories have also to stand as complete and exclusive basis for applications.
Such a complete and exclusive mapping to application is de-facto guaranteed by continuous and incremental development, independently of the business value of stories. Not so with intermediate models which, given the semantic discontinuity, may create back-doors for broader concerns, e.g when some features are redefined through generalization. Hence the benefits of a clarity of purpose:
Users’ stories stand for specific requirements meant to be captured and coded by increments. Documentation should be limited to application maintenance and not confused with analysis models.
Use cases should be introduced when stories are to be consolidated or broader concerns factored out , e.g the consolidation of features or business cases.
Sorting out the specifics of users concerns while keeping them in line with business models is at the core of business analysts job description. Since that distinction is seldom directly given in requirements, it could be made easier if aligned on modeling options: stories and specialization for users concerns, models and generalization for business features.
From Stories to Cases
The generalization of digital environments entails structural and operational adjustments within enterprise architectures.
At enterprise level the integration of homogeneous digital flows and heterogeneous symbolic representations can be achieved through enterprise architectures and profiled ontologies. But that undertaking is contingent on the way requirements are first dealt with, namely how the specifics of users’ needs are intertwined with business designs.
As suggested above, modeling schemes could help to distinguish as well as consolidate users narratives and business outlooks, capturing the former with users’ stories and the latter with use cases models.
That would neatly align means (part played by supporting systems) with ends (users’ stories vs business cases):
Users’ stories describe specific objectives independently of the part played by supporting systems.
Use cases describe the part played by systems taking into account all supported stories.
It must be stressed that this correspondence is not a coincidence: the consolidation of users’ stories into broader business objectives becomes a necessity when supporting systems are taken into account, which is best done with use cases.
Aligning Stories with Cases
Stories and models are orthogonal descriptions, the former being sequenced, the latter laid out; it ensues that correspondences can only be carried out for individuals uniformly identified (#) at enterprise and systems level, specifically: roles (aka actors), events, business objects, and execution units.
It must be noted that this principle is supposed to apply independently of the architectures or methodologies considered.
With continuity and consistency of identities achieved at architecture level, the semantic discontinuity between users’ stories and models (classes or use cases) can be managed providing a clear distinction is maintained between:
Modeling abstractions, introduced by requirements analysis and applied to artifacts identified at architecture level.
The semantics of attributes and operations, defined by users’ stories and directly mapped to classes or use cases features.
Finally, stories and cases need to be anchored to epics and enterprise architecture.
Business Cases & Enterprise Stories
Likening epics to enterprise stories would neatly frame the panoply of solutions:
At process level users’ stories and use cases would be focused respectively on specific business concerns and supporting applications.
At architecture level business stories (aka epics) and business cases (aka plots) would deal respectively with business models and objectives, and supporting systems capabilities.
That would provide a simple yet principled basis for enterprise architectures governance.
All too often choosing a development method is seen as a matter of faith, to be enforced uniformly whatever the problems at hand.
As it happens, this dogmatic approach is not limited to procedural methodologies but also affect some agile factions supposedly immunized against such rigid stances.
A more pragmatic approach should use simple and robust principles to pick and apply methods depending on development problems.
Iterative vs Phased Development
Beyond the variety of methodological dogmas and tools, there are only two basic development patterns, each with its own merits.
Iterative developments are characterized by the same activity (or a group of activities) carried out repetitively by the same organizational unit sharing responsibility, until some exit condition (simple or combined) verified.
Phased developments are characterized by sequencing constraints between differentiated activities that may or may not be carried out by the same organizational units. It must be stressed that phased development models cannot be reduced to fixed-phase processes (e.g waterfall); as a corollary, they can deal with all kinds of dependencies (organizational, functional, technical, …) and be neutral with regard to implementations (procedural or declarative).
A straightforward decision-tree can so be built, with options set by ownership and dependencies:
Shared Ownership: Agile Schemes
A project’s ownership is determined by the organizational entities that are to validate the requirements (stakeholders), and accept the products (users).
Iterative approaches, epitomized by the agile development model, is to be the default option for projects set under the authority of single organizational units, ensuring shared ownership and responsibility by business analysts and software engineers.
Projects set from a business perspective are rooted in business processes, usually through users’ stories or use cases. They are meant to be managed under the shared responsibility of business analysts and software engineers, and carried out independently of changes in architecture capabilities (a,b).
Projects set from a system perspective potentially affect architectures capabilities. They are meant to be managed under the responsibility of systems architects and carried out independently of business applications (d,b,c).
Transparency and traceability between the two perspectives would be significantly enhanced through the use of normalized capabilities, e.g from the Zachman’s framework:
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.
It must be noted that as far as architecture and business driven cycles don’t have to be synchronized (principle of continuous delivery), the agile development model can be applied uniformly; otherwise phased schemes must be introduced.
Cross Dependencies: Phased Schemes
Cross dependencies mean that, at some point during project life-cycle, decision-making may involve organizational entities from outside the team. Two mechanisms have traditionally been used to cope with the coordination across projects:
Fixed phases processes (e.g Analysis/Design/Implementation) have shown serious shortcomings, as illustrated by notorious waterfall.
Milestones improve on fixed schemes by using check-points on development flows instead of predefined activities. Yet, their benefits remain limited if development flows are still defined with regard to the same top-down and one-fits-all activities.
Model based systems engineering (MBSE) offers a way out of the dilemma by defining flows directly from artifacts. Taking OMG’s model driven architecture (MDA) as example:
Computation Independent Models (CIMs) describe business objects and activities independently of supporting systems.
Platform Independent Models (PIMs) describe systems functionalities independently of platforms technologies.
Platform Specific Models (PSMs) describe systems components as implemented by specific technologies.
Projects can then be easily profiled with regard to footprints, dependencies, and iteration patterns (domain, service, platform, or architecture, …).
That understanding puts the light on the complementarity of agile and phased solutions, often known as scaled agile.
Digital environments and the ubiquity of software in business processes introduces a new perspective on value chains and the assessment of supporting applications.
At the same time, as software designs cannot be detached of architectures capabilities, the central question remains of allocating costs and benefits between primary and support activities .
Value Chains & Activities
The concept of value chain introduced by Porter in 1985 is meant to encompass the set of activities contributing to the delivery of a valuable product or service for the market.
Taking from Porter’s generic model, various value chains have been refined according to business specific categories for primary and support activities.
Whatever their merits, these approaches are essentially static and fall short when the objective is to trace changes induced by business developments; and that flaw may become critical with the generalization of digital business environments:
Given the role and ubiquity of software components (not to mention smart ones), predefined categories are of little use for impact analysis.
When changes in value chains are considered, the shift of corporate governance towards enterprise architecture puts the focus on assets contribution, cutting down the relevance of activities.
Hence the need of taking into account changes, software development, and enterprise architectures capabilities.
Value Added & Software Development
While the growing interest for value chains in software engineering is bound to agile approaches and business driven developments, the issue can be put in the broader perspective of project planning.
With regard to assessment,stakeholders, start with business opportunities and look at supporting systems from a black box perspective; in return, software providers are to analyze requirements from a white box perspective, and estimate corresponding development effort and time delivery.
Assuming transparency and good faith, both parties are meant to eventually align expectations and commitments with regard to features, prices, and delivery.
With regard to policies, stakeholders put the focus on returns on investment (ROI), obtained from total cost of ownership, quality of service, and timely delivery. Providers for their part try to minimize development costs while taking into account effective use of resources and costs of opportunities. As it happens, those objectives may be carried on as non-zero sum games:
Business stakeholders foretell the actualized returns (a) to be expected from the functionalities under consideration (b).
Providers consider the solutions (b’) and estimate actualized costs (a’).
Stakeholders and providers agree on functionalities, prices and deliveries (c).
Assuming that business and engineering environments are set within different time-frames, there should be room for non-zero-sum games winding up to win-win adjustments on features, delivery, and prices.
Continuous vs Phased Alignments
Notwithstanding the constraints of strategic planning, business processes are by nature opportunistic, and their ability to be adjusted to circumstances is becoming all the more critical with the generalization of digital business environments.
Broadly speaking, the squaring of supporting applications to business value can be done continuously or by phases:
Phased alignments start with some written agreements with regard to features, delivery, and prices before proceeding with development phases.
Continuous alignment relies on direct collaboration and iterative development to shape applications according to business needs.
Beyond sectarian controversies, each approach has its use:
Continuous schemes are clearly better at harnessing value chains, providing that project teams be allowed full project ownership, with decision-making freed of external dependencies or delivery constraints.
Phased schemes are necessary when value chains cannot be uniquely sourced as they take roots in different organizational units, or if deliveries are contingent on technical constraints.
In any case, it’s not a black-and-white alternative as work units and projects’ granularity can be aligned with differentiated expectations and commitments.
Work Units & Architecture Capabilities
While continuous and phased approaches are often opposed under the guises of Agile vs Waterfall, that understanding is misguided as it extends the former to a motley of self-appointed agile schemes and reduces the latter to an ill-famed archetype.
Instead, a reasoned selection of a development models should be contingent on the problems at hand, and that can be best achieved by defining work-units bottom-up with regard to the capabilities targeted by requirements:
Development patterns could then be defined with regard to architecture layers (organization and business, systems functionalities, platforms implementations) and capabilities footprint:
Phased: work units are aligned with architecture capabilities, e.g : business objects (a), business logic (b), business processes (c), users interfaces (d).
Iterative: work units are set across capabilities and defined dynamically according to development problems.
That would provide a development framework supporting the assessment of iterative as well as phased projects, paving the way for comprehensive and integrated impact analysis.
Value Chains & Architecture Capabilities
As far as software engineering is concerned, the issue is less the value chain itself than its change, namely how value is to be added along the chain.
To summarize, the transition to this layout is carried out in two steps:
Conceptually, Zachman’s original “Why” column is translated into a line running across column capabilities.
Graphically, the five remaining columns are replaced by embedded pentagons, one for each architecture layer, with the new “Why” line set as an outer layer linking business value to architectures capabilities:
That apparently humdrum transformation entails a significant shift in focus and practicality:
The focus is put on organizational and business objectives, masking the ones associated to systems and platforms layers.
It makes room for differentiated granularity in the analysis of value, some items being anchored to specific capabilities, others involving cross dependencies.
Value chains can then be charted from business processes to supporting architectures, with software applications in between.
As pointed above, the crumbling of traditional fences and the integration of enterprise architectures into digital environments undermine the traditional distinction between primary and support activities.
To be sure, business drive is more than ever the defining factor for primary activities; and computing more than ever the archetype of supporting ones. But in between the once clear-cut distinctions are being blurred by a maze of digital exchanges.
In order to avoid a spaghetti heap of undistinguished connections, value chains are to be “colored” according to the nature of links:
Between architectures capabilities: business and organization (enterprise), systems functionalities, or platforms and technologies.
Between architecture layers: engineering processes.
When set within that framework, value chains could be navigated in both directions:
For the assessment of applications developed iteratively: business value could be compared to development costs and architecture assets’ depreciation.
For the assessment of features (functional or non functional) to be shared across business applications: value chains will provide a principled basis for standard accounting schemes.
Combined with model based system engineering that could significantly enhance the integration of enterprise architecture into corporate governance.
Computation independent models (CIMs) describe organization and business processes independently of the role played by supporting systems.
Platform independent models (PIMs) describe the functionalities supported by systems independently of their implementation.
Platform specific models (PSMs) describe systems components depending on platforms and technologies.
Engineering processes can then be phased along architecture layers (a), or carried out iteratively for each application (b).
When set across activities value chains could be engraved in CIMs and refined with PIMs and PSMs(a). Otherwise, i.e with business value neatly rooted in single business units, value chains could remain implicit along software development (b).