User Stories Vs Specifications: Finding The Right Level Of Abstraction

Defining the Problem: Finding the Optimal Level of Abstraction

Software requirements exist on a spectrum from high-level user needs to detailed technical specifications. On one end, user stories capture requested functionality in an agile, user-centric way. On the other, technical specs thoroughly define system behavior for implementation. Where along this spectrum of abstraction should requirements be focused? If too high-level, needed details get overlooked. If too low-level, sight of the big picture gets lost. Like Goldilocks tasting bowls of porridge, finding the right level takes work to get “just right.”

Why Abstraction Matters in Software Requirements

Abstraction reduces information down to essential meaning. High-level abstraction focuses on overarching needs and purposes. Low-level details concrete implementation artifacts. Most software solutions require operating at multiple tiers of abstraction simultaneously across user, system, and component perspectives. The art is selecting the appropriate level at each point of definition. Too little abstraction risks getting lost in ancillary details unrelated to core user goals. Excessive abstraction loses sight of technical realities constraints necessary to actually deliver working software that solves problems.

Balancing High-Level User Needs and Detailed Technical Specs

Tension exists between user stories and technical specifications. User stories put emphasis on terse descriptions of desired value for the user. Specs focus on precise technical behavior of system components. While closely related, focusing too heavily on one risks loss of direction on the other. Keeping complementary connection between both abstraction types helps ensure high-level needs get satisfied through detailed functionality…and low-level behaviors trace back to genuine user goals. Through iterative refinement, abstraction levels align into unified vision between agile product owners and delivery teams.

When to Use User Stories vs Specifications

User stories excel during agile exploration of solution ideas. Brief three-part name-action-purpose format concisely captures essential intent from the user perspective without bogging down into details prematurely. As placeholder epics, stories signal customer importance while deferred commitment allows flexibility responding to discoveries during analysis and development cycles. The emphasis stays on quickly learning what provides end user value.

Whereas specifications come into play once clearer sense of technical directions emerge. The analytical nature help reconcile user needs with architectural realities as the solution takes shape. Specs influence downstream activities of system design, component development, integration testing, and operational deployment. But because significant upfront time for authoring complete specification documents runs counter to agile principles, lean documentation guidance applies for keeping specs sufficient but lightweight.

Writing User Stories to Capture User Needs

Stories express desired user goals free from constraints of specific solutions. Focus stays on conveying meaning rather than spelling out details. Using framework of “As a [user role], I want [some motivation], so that [value or benefit]” pushes clarity on perspective and purpose. Additional description attributes context as warranted, but resists diluting the core user need. Well-formed stories strongly connect subject-verb-object elements to intentions of associated user segment.

Further enhanced through descriptive adjective expanding on entities and semantic relationship triples explaining connections with other conceptual entities in the solution space. Carefully chosen phrasing and structured language patterns help user stories signal priorities, paint pictures of usage, and purvey purpose in ways readily understood by agile product owners not closest to technical details of underlying system constraints.

Including Acceptance Criteria for Clarity

Augmenting user stories with acceptance criteria bridges abstraction gap with specifications needed for implementation planning. These clarifying sub-elements enumerate detailed conditions system behavior must satisfy to meet encapsulated user need. Using “Given [preconditions] when [activity occurs], then [expectations]” structure grounds criteria as logical testable artifacts while keeping system component details encapsulated.

For example: given user is authenticated member of ecommerce site…when user adds item to shopping cart…then cart quantity updated, cart total recalculated, and confirmation message displayed. Acceptance criteria become inputs for downstream translation into software product capabilities. But keeping specification level details bound to story context prevents drifting into unnecessary upfront technical paralysis.

Structuring Technical Specifications for Implementation

If user stories say why software solutions will provide value, specifications say how to build it. Organizing specifications involves breaking down coherent chunks of functionality into modular interfaces consumable by design and development teams. Decomposing major subsystems into progressively smaller objects helps distribute complexity at manageable grains.

Common convention utilizes hierarchical numbered headings denoting scope of increasing specificity. Sections address overarching system behaviors, subsystem contexts, software components, applicable data structures/algorithms, and transaction/message sequencing. Text and diagrams guide constraints, logic, events, outputs, and error conditions. Structure promotes comprehension for implementers to translate guidance into compilable source code and executable programs.

Providing Examples to Illustrate Specifications

Supplementing technical specifications with illustrative examples aids understanding by grounding concepts in tangible use cases. Samples demonstrate input/output pairs and illusion complex processing rules. Variety shows breadth of applicability across edge scenarios while repetition builds intrinsic familiarity with core functionality likely comprising majority of real-world usage.

For instance, an ecommerce catalog service interface for searching items by product category and price range gets exercise by examples like: children’s books under $25, action movies under $15, hiking boots between $50-100, etc. Code samples in suitable programming language can directly execute to validate software behaviors meet information and performance criteria.

Achieving Alignment Between User Stories and Technical Specs

Tracing specificity hierarchy across requirement types keeps solutions focused on actual user goals. Relating elements of technical specifications back to parent user stories checks that planned behaviors satisfy originating needs. Similarly, acceptance criteria associated with stories guide discovery of gaps requiring additional investigation at appropriate level of abstraction.

Two-way alignment mapping through cross-referencing links constantly reorients to bigger picture even when mired in implementation details. For example, ensuring subsystem responsible for shopper personalization and promotions always reflects back to higher-level stories around customized content discovery intending to improve user experiences and conversion rates.

Recommendations for Determining the Right Level of Abstraction

Finding ideal balance between user and system perspectives is challenging yet rewarding endeavor. Keepuser needs in sight but don’t neglect technical realities. Reconcile through tools bridging abstraction levels and bidirectional traceability. Employ lean documentation proportional to uncertainty and project scale. Reevaluate pending questions as answers emerge from analysis and prototypes. Adjust abstraction as understanding deepens through feedback loops revealing missing insights. By focusing on adding value, continue abstraction refinement till requirements complete and consistent at all necessary tiers. The sweet spot hits just at moment when software fulfills its essential purpose.