Category: Ontologies

Focus: Individuals in Models

Preamble

Models are meant to characterize categories of given (descriptive models), designed (prescriptive models), or hypothetical (predictive models) individuals.

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Identity Matter (Terracotta Soldiers of Emperor Qin Shi Huang)

Insofar as purposes can be kept apart, the discrepancies in targeted individuals can be ironed out, notably by using power-types. Otherwise, e.g if modeling concerns mix business analysis with software engineering, meta-models are introduced as jack-of-all-trades to deal with mixed semantics.

But meta-models generate exponential complexity when used across domains, not to mention the open and fuzzy ones of business intelligence. What is at stake can be better understood through the way individuals are identified and represented.

Partitions & Abstraction

Since models are meant to classify instances with regard to concerns, mixing concerns is to entail mixed classifications, horizontally across domains (e.g business and accounting), or vertically along engineering cycles (e.g business and engineering).

That can be achieved with power-types, meta-classes, or ontologies.

Delegation & Power-types

Given that categories (or classes or types) represent set of instances (given, designed, or simulated), they may by themselves be regarded as symbolic instances used to manage features commonly valued by their own members.

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Power-types are simultaneously categories and instances.

This approach is consistent as well as effective providing the semantics and identities of instances are shared by all agents concerned, e.g business and technical aspects of car rentals. Yet it falls short on both accounts when abstractions levels a set across  domains, inducing connectors with different semantics and increased complexity.

Abstraction & Sub-classes

Sub-classes often appear as a way to overcome the difficulty, as illustrated by the Hepp Research’s Vehicle Sales Ontology: despite being set at different abstraction levels, instances for cars and models are defined and identified uniformly.

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If, in that case, the model fulfils the substitution principle for external consistency, sub-types will fall short if engineering concerns were to be taken into account because the set of individual car models could then differ depending on perspective.

Meta-classes & Stereotypes

The overuse of meta-classes and stereotypes epitomizes the escapism school of modeling. That may be understandable, if not helpful, for the former which is by nature a free pass to abstraction; less so for the latter which is supposed to go the other way toward the specialization of meta-classes according to specific profiles. It ensues that stereotypes should never be used on their own or be extended by another stereotype.

As it happens, such consistency concerns appear to be easily diluted when stereotypes are jumbled with meta constructs; e.g:

  • Abstract stereotype (a).
  • Strong (aka class) inheritance of abstract stereotype from concrete meta-class (b).
  • Weak inheritance (aka aspect) between stereotypes (c, f).
  • Meta-constraint used to map Vehicle to methodology stereotype (d).
  • Domain specific connector to stereotype (e).

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Without comprehensive and consistent semantics for instances and abstractions, individuals cannot be solidly mapped to models:

  • Individual concepts (car, horse, boat, …) have no clear mooring.
  • Actual vehicles cannot be tied to the meta-class or the abstract stereotype.
  • There is no strong inheritance tying individuals models and rental cars to an identification mechanism.

Assuming that detachment is not an option, the basis of models must be reset.

Ontologies & open concepts

Put in simple words, ontologies are meant to examine the nature and categories of existence, in general (metaphysics) or in specific contexts. As for the latter, they can be applied to individuals according to the nature of their existence (aka epistemic identity): concepts, documents, categories and aspects.

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As it happens, sorting things out makes the whole paraphernalia of meta-classes and stereotypes no longer needed because the semantics of inheritance and associations can be set according to the nature of individuals.

That can be illustrated with OWL 2 and the Caminao Ontological Kernel (CaKe_WIP):

  • Categories associated to business entities managed through symbolic counterparts (_#): rental cars and vehicle models
  • Partitions (_2): structural (Body style) or functional (Rental group).
  • Instances of actual objects (Rental car: Clio58642) and categories (Model:Clio, Body style: Sedan, Propulsion: combustion). 

With individuals solidly rooted in targeted domains, models can then fully serve their purposes.

What’s the Point

It’s worth to remind that models have to be built on purpose, which cannot be achieved without a clear understanding of context and targets. Here are some examples:

Quality arguably come first:

  • External consistency: to be checked by mapping individuals in analysis categories to big data.
  • Internal consistency: to be checked by mapping individuals in design classes to observed or simulated run-time components.
  • Acceptance: automated tests generation.

Then, individuals could be used to map models to past and future, the former for refactoring, the latter for business intelligence.

Refactoring looks to the past but is frustrated by undocumented legacy code. Combined with machine learning, individuals could help to bridge the gap between code and models.

Business Intelligence looks the other way as it is meant to map hypothetical business objects and behaviors to the structures and semantics already managed by information systems. As in reversal of legacy benefits, individuals could provide cues to new business meanings.

Finally, maturity assessment and optimization of enterprise processes fully depend on the reliability of their basis.

Further Reading

Collaborative Systems Engineering: From Models to Ontologies

Given the digitization of enterprises environments, engineering processes have to be entwined with business ones while kept in sync with enterprise architectures. That calls for new threads of collaboration taking into account the integration of business and engineering processes as well as the extension to business environments.

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Collaboration can be personal and direct, or collective and mediated (Wang Qingsong)

Whereas models are meant to support communication, traditional approaches are already straining when used beyond software generation, that is collaboration between humans and CASE tools. Ontologies, which can be seen as a higher form of models, could enable a qualitative leap for systems collaborative engineering at enterprise level.

Systems Engineering: Contexts & Concerns

To begin with contents, collaborations should be defined along three axes:

  1. Requirements: business objectives, enterprise organization, and processes, with regard to systems functionalities.
  2. Feasibility: business requirements with regard to architectures capabilities.
  3. Architectures: supporting functionalities with regard to architecture capabilities.

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Engineering Collaborations at Enterprise Level

Since these axes are usually governed by different organizational structures and set along different time-frames, collaborations must be supported by documentation, especially models.

Shared Models

In order to support collaborations across organizational units and time-frames, models have to bring together perspectives which are by nature orthogonal:

  • Contexts, concerns, and languages: business vs engineering.
  • Time-frames and life-cycle: business opportunities vs architecture stability.

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Harnessing MBSE to EA

That could be achieved if engineering models could be harnessed to enterprise ones for contexts and concerns. That is to be achieved through the integration of processes.

 Processes Integration

As already noted, the integration of business and engineering processes is becoming a key success factor.

Processes integration

For that purpose collaborations would have to take into account the different time-frames governing changes in business processes (driven by business value) and engineering ones (governed by assets life-cycles):

  • Business requirements engineering is synchronic: changes must be kept in line with architectures capabilities (full line).
  • Software engineering is diachronic: developments can be carried out along their own time-frame (dashed line).

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Synchronic (full) vs diachronic (dashed) processes.

Application-driven projects usually focus on users’ value and just-in-time delivery; that can be best achieved with personal collaboration within teams. Architecture-driven projects usually affect assets and non-functional features and therefore collaboration between organizational units.

Collaboration: Direct or Mediated

Collaboration can be achieved directly or through some mediation, the former being a default option for applications, the latter a necessary one for architectures.

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Both can be defined according to basic cognitive and organizational mechanisms and supported by a mix of physical and virtual spaces to be dynamically redefined depending on activities, projects, locations, and organisation.

Direct collaborations are carried out between individuals with or without documentation:

  • Immediate and personal: direct collaboration between 5 to 15 participants with shared objectives and responsibilities. That would correspond to agile project teams (a).
  • Delayed and personal: direct collaboration across teams with shared knowledge but with different objectives and responsibilities. That would tally with social networks circles (c).

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Collaborations

Mediated collaborations are carried out between organizational units through unspecified individual members, hence the need of documentation, models or otherwise:

  • Direct and Code generation from platform or domain specific models (b).
  • Model transformation across architecture layers and business domains (d)

Depending on scope and mediation, three basic types of collaboration can be defined for applications, architecture, and business intelligence projects.

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Projects & Collaborations

As it happens, collaboration archetypes can be associated with these profiles.

Collaboration Mechanisms

Agile development model (under various guises) is the option of choice whenever shared ownership and continuous delivery are possible. Application projects can so be carried out autonomously, with collaborations circumscribed to team members and relying on the backlog mechanism.

The OODA (Observation, Orientation, Decision, Action) loop (and avatars) can epitomize projects combining operations, data analytics, and decision-making.

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Collaboration archetypes

Projects set across enterprise architectures cannot be carried out without taking into account phasing constraints. While ill-fated Waterfall methods have demonstrated the pitfalls of procedural solutions, phasing constraints can be dealt with a roundabout mechanism combining iterative and declarative schemes.

Engineering vs Business Driven Collaborations

With collaborative engineering upgraded at enterprise level, the main challenge is to iron out frictions between application and architecture projects and ensure the continuity, consistency and effectiveness of enterprise activities. That can be achieved with roundabouts used as a collaboration mechanism between projects, whatever their nature:

  • Shared models are managed at roundabout level.
  • Phasing dependencies are set in terms of assertions on shared models.
  • Depending on constraints projects are carried out directly (1,3) or enter roundabouts (2), with exits conditioned by the availability of models.

Engineering driven collaboration: roundabout and backlogs

Moreover, with engineering embedded in business processes, collaborations must also bring together operational analytics, decision-making, and business intelligence. Here again, shared models are to play a critical role:

  • Enterprise descriptive and prescriptive models for information maps and objectives
  • Environment predictive models for data and business understanding.

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Business driven collaboration: operations and business intelligence

Whereas both engineering and business driven collaborations depend on sharing information  and knowledge, the latter have to deal with open and heterogeneous semantics. As a consequence, collaborations must be supported by shared representations and proficient communication languages.

Ontologies & Representations

Ontologies are best understood as models’ backbones, to be fleshed out or detailed according to context and objectives, e.g:

  • Thesaurus, with a focus on terms and documents.
  • Systems modeling,  with a focus on integration, e.g Zachman Framework.
  • Classifications, with a focus on range, e.g Dewey Decimal System.
  • Meta-models, with a focus on model based engineering, e.g models transformation.
  • Conceptual models, with a focus on understanding, e.g legislation.
  • Knowledge management, with a focus on reasoning, e.g semantic web.

As such they can provide the pillars supporting the representation of the whole range of enterprise concerns:

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Taking a leaf from Zachman’s matrix, ontologies can also be used to differentiate concerns with regard to architecture layers: enterprise, systems, platforms.

Last but not least, ontologies can be profiled with regard to the nature of external contexts, e.g:

  • Institutional: Regulatory authority, steady, changes subject to established procedures.
  • Professional: Agreed upon between parties, steady, changes subject to established procedures.
  • 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).

Cross profiles: capabilities, enterprise architectures, and contexts.

Ontologies & Communication

If collaborations have to cover engineering as well as business descriptions, communication channels and interfaces will have to combine the homogeneous and well-defined syntax and semantics of the former with the heterogeneous and ambiguous ones of the latter.

With ontologies represented as RDF (Resource Description Framework) graphs, the first step would be to sort out truth-preserving syntax (applied independently of domains) from domain specific semantics.

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RDF graphs (top) support formal (bottom left) and domain specific (bottom right) semantics.

On that basis it would be possible to separate representation syntax from contents semantics, and to design communication channels and interfaces accordingly.

That would greatly facilitate collaborations across externally defined ontologies as well as their mapping to enterprise architecture models.

Conclusion

To summarize, the benefits of ontological frames for collaborative engineering can be articulated around four points:

  1. A clear-cut distinction between representation semantics and truth-preserving syntax.
  2. A common functional architecture for all users interfaces, humans or otherwise.
  3. Modular functionalities for specific semantics on one hand, generic truth-preserving and cognitive operations on the other hand.
  4. Profiled ontologies according to concerns and contexts.

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Clear-cut distinction (1), unified interfaces architecture (2), functional alignment (3), crossed profiles (4).

A critical fifth benefit could be added with regard to business intelligence: combined with deep learning capabilities, ontologies would extend the scope of collaboration to explicit as well as implicit knowledge, the former already framed by languages, the latter still open to interpretation and discovery.

P.S.

Knowledge graphs, which have become a key component of knowlege management, are best understood as a reincarnation of ontologies.

Further Reading