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Published byValentine Patrick Modified over 9 years ago
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Why Written Requirements? Unambiguous Defines goals Cost of finding a requirements bug later can be 100 times more expensive
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Mars Climate Orbiter (Dec 98) Intended to orbit Mars Supposed to provide output in newton seconds Instead crashed into it Instead provided in pound-force seconds Minimum distance: 80 km
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From Client to Plan user stories and personasuse cases and user typesrequirementsfunctional specuser manual and plan
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Fundamental Steps StepDocumentation Requirements Design Implementation Test Deployment Maintenance Functional Spec Design Document Code Test Plan User Documentation Design Document
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Our Requirements Process Personas and User StoriesUser Types and Use CasesRequirements
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Our Requirements Phase What does the client want to do? User stories – his (or her) terms Use cases – your terms Extract the essence: requirements Requirements document as a tool This product should … Translate to a system: functional spec
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Understanding Users Identify the user groups Understand their goals Determine the total user experience How users perform their tasks now Task and goal descriptions, importance ranking, strategies, measures, and targets Stories and scenarios describing how they currently perform their tasks
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User Characterization Knowledge and experience Age and gender Physical handicaps Characteristics of tasks and jobs Psychological characteristics
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Personas A description of a fictitious user representing a distinct user group User groups are based on unique characteristics Each persona represents a unique set of goals for design Personas drive User-Centered Design (UCD) Data-based personas Microsoft Microsoft Persona Power Persona Power
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Persona excerpt (hotel reservation)
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Purported Benefits of Personas Establishes users’ goals and needs Provides manageable set of users Reduces gathering of user requirements Focuses on what users will use Prioritizes design efforts Resolves disagreements over design decisions Reduces usability tests
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Fundamental Benefit Makes it easier to reason about the person and predict how they might behave
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User Stories From the USER’s perspective Capture what the user is trying to do Different stories may trigger same function BUT different concerns, sequences, constraints Examples Same user planning a trip for business or pleasure Or buying an item for himself or as a gift
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Why User Stories From the USER’s perspective Capture what the user is trying to do Different stories may trigger same function BUT different concerns, sequences, constraints Examples Same user planning a trip for business or pleasure Or buying an item for himself or as a gift Comes from agile programming model SHORT: fit on an index card Learn them from the client
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User Types: Broad, easily described Typically self-explanatory Never more than a sentence or phrase Casual user, new user, experienced user
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Generalizing to Use Cases A statement of the functionality users expect and need, organized by functional units Different from user stories because they are from the software’s perspective Functional units are any natural division Relationships between user types and use cases User activities, decisions, and objects involved In terms of user types: classifications that the system recognizes
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Documenting Use Cases UML diagrams Simple text description
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Use Case Diagram Defines the outside view Elements Actors (stick figures): anything outside the system that interacts with it Use cases (ovals): procedures by which the actor interacts with the system Solid lines: indicate how actors interact
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Use Case Extensions Dotted lines: show dependencies between procedures Includes (subroutine) Extends (variation)
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Example of Use Case (customer name)
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Use Case Usage determining features (requirements) basis for communicating with clients generating test cases
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Documenting Use Cases We will use simple text description Examples from prior years Butterfly Lab Foreign Language Resource Center
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