Focus: Users’ Stories & Use Cases

Preamble

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 words in progress for the former, etched statements for the latter.

Kara_Walker_mural2
Running Stories (Kara Walker)

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.)

Scratch_lang
Semantic continuity (c>p) and discontinuity (c>m>p)

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).

Confusion may arise when users’ stories are understood as a documented basis for further developments; and that confusion between outcomes (coding vs modeling) is often compounded by one between intents (users concerns vs business cases).

Concerns: Users’ Stories vs Business Cases

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.

Scratch_USC1
Use cases describe the part played by systems taking into account all supported stories.

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.

Scratch_US2C
Crossing cases with stories: events, roles, business objects, and execution units must be uniformly and consistently identified (#) .

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.
Scratch_USC3
From Capture to Analysis: Abstractions introduce a semantic discontinuity

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 epics and business cases would deal respectively with business models and objectives,  and supporting systems capabilities.
EASquare_stocas
A Squared frame for enterprise architectures governance

That would provide a simple yet principled basis for enterprise architectures governance.

Further Reading

External Links

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.