Use Cases Revisited

In the eyes of the beholders (Paul McCarthy)

Preamble

EA & Ontological Prisms

Ontological prisms are used to represent enterprise architectures and environments:

  • Facts, for instances of objects or phenomena that can be identified outside of the organisation or system considered
  • Concepts, for named ideas and activities that can be defined independently of their existence
  • Categories, for the description of sets of objects or phenomena
Maps & Territories

They ensure the interoperability of representations and consequently the functional integration of enterprise architecture undertakings:

EA Functionalities
  • Requirements, for actual business needs
  • Data analytics, for virtual business needs
  • Business analysis, for the alignment of virtual business needs with business models and objectives
  • Business intelligence for the definition of business models and objectives
  • Strategic planning, for the alignment of business models and objectives with organisation and supporting systems
  • Systems modeling, for the management of systems
  • Systems engineering, for the alignment of new developments and legacy systems

Changes can then be described with regard at enterprise or system level.

Cases & Stories

Changes in enterprises’ organisation and systems can be prescribed from three perspectives:

  • Use cases, for interactions between systems and enterprises’ physical and symbolic environments (individual level)
  • User stories, for business activities independently of supporting systems (individual level)
  • Business cases, for the tie-ups between organisations and systems (enterprise level)

It must be noted that prescriptions at individual level refer to actual environments (physical or symbolic) and are carried out through direct communication; by contrast prescriptions at enterprise level refer to symbolic representations and are carried out through mediated communication. It must also be noted that these perspectives may or may not be explored independently, yet developed consistently.

Use Cases Through Prisms

Use Cases as Black-boxes

As originally defined by Ivar Jacobson, the aim of use cases (UCs) is to describe what happens between users and systems. Strictly speaking, UCs thus entail a primary actor (possibly seconded) and a triggering event (possibly qualified); what happen then may (eg transaction) or may not (eg batch) entail subsequent exchange of messages. Seen as black-boxes UCs can thus be defined by:

  • A primary actor (aka role) and triggering event
  • Assertions with regard to the state of relevant objects, agents, and processes in environment
  • Assertions with regard to the state of relevant representations managed by systems
  • Messages exchanged
  • Transcripts and documents pertaining to business rules and dialog control
Use cases as black-boxes

Yet, enterprise digital immersion and advances in language models are inducing a comprehensive overhaul of user interfaces, and consequently a reset of use cases’ remit.

Augmented Use Cases

As an established way to describe interactions with systems use cases have for long been relying on Graphical user interfaces (GUI) for communication; but advances in Generative AI (GAI) technologies and natural language processing are reshuffling the designs of user interfaces, undermining the distinction with applications, and more critically the distinction between language and knowledge; hence the benefits of introducing ontological prisms:

Putting Languages Front and Center
  • Natural language interfaces, pervading a wide range of systems, in front of end-users as well as between applications
  • Linguistic layers (syntactic, lexical, semantics, pragmatics), providing the symbolic bridges across the representations of facts (data), categories (information), and concepts (knowledge), with thesauruses, schemas, and ontologies serving as gears.

Use cases could thus be reset in the broader context of enterprise organisational and operational contexts:

  • Functional integration, for the consistency of business assertions and returns on DB queries
  • Operational acceptance, for the consistency of business logic (user stories) and use cases execution (queries)
  • Business validation, for the consistency of user and business stories
Augmented Cases

Combining ontological prisms and generative language technologies could ensure a functional integration of resources (data), assets (information), and services (knowledge), and the interoperability of use cases, users stories, and business cases.

Further Readings

Kaleidoscope Series

Other Caminao References