INF 113 Midterm 2

When are full-fledged requirements needed?

• When customers want contractually-fixed requirements, costs, and deadlines

• Systems are built by an external contractor based on a set of given requirements (outsourcing)

• In regulated environments where regulators check compliance of developed systems (ex: government)

What is the purpose of a glossary?

Danger of missing shared understanding in terminology

Glossary

Context specific terms

Everyday terms that have special meaning in given context

Abbreviations and acronyms

When do you use formal specification languages?

Specify most critical sections of requirements doc

Specify stable requirements

When do you use more/less detail in RE?

More:

External client, development will be outsourced, members are geographically dispersed, testing will be based on requirments, accurate estimates are needed

Less:

Work being done interanlly, customers are extensively involved, developers have domain experience, precedents are avialable as when previous application is being replaced

What qualities should you strive for?

Correct, understandlable, verifiable, unambiguous, complete, necessary, feasible, consistent, conformant, modifiable, non-redundant, structured, traceable to other artifacts

Most important: correctness, understandability, verifiability, consistency

How to rewrite poorly-written requirements

Use shall

Avoid imprecise terminology (etc, fast)

Make it measurable

How do you create a user story?

As a <role> I want <activity> so that <business value>

Should be: independent, negotiable, valuable, estimatable, sized appropriately (5-15 stories), testable

Activity should be part of the system

Role should be a user

Good acceptance criteria

Time Facet:

Linear: Requirements specified up front, contractual basis for outsourcing (developers are not in same company as customers), regulatory authorities

Iterative: Requirements are specified incrementally, starting with goals, development process is iterative/agile, stakeholders are avialable for short feedback looks, duraiton of proaject allows for more than 1-2 iterations, abiliy to change

Purpose Facet

Prescriptive: Contract where requirements are binding and must be implemented, fixed price, functionality determines cost/deadlines, outsoucred

Explorative: Know goals but requirements have to be explored, stakeholders are involved/have vague idea, deadline over functionality, framework contract, priority of requirements is unclear

Target Facet

Customer-specific: Order by a customer and developed bya supplier for this customer, system will be used by organization who ordered the system, indivdal person can be identified for stakeholder role, wants a requirements specification

Market-oriented: Developed as a product/service for a market, developing organization intends to sell the system as a product, users are not indiviaully idenifiable

Process Configurations

Participatory: Iterative, explorative, customer-specific

• Customer is strongly involved

• Product backlog w/ user stories or task descriptions

• Continuous interaction between stakeholders

Contractual: Linear/Iterative (sometimes), prescriptive, customer-specific

• Little stakeholder interaction after requirements, contractual basis

• System requirements specification with textual requirements and models

• From stakeholders to requirements engineers

Product-oriented: Iterative, explorative, market-oriented

• Sell it as a product

• Product backlog w/ user stores or task descriptions

• Interaction between product owner, marketing, re engineers

Characteristics of an Ideal RE Process

Interactive: Iterative and explorative

Intensive collaboration between stakeholders and re engineer

Short feedback cycle

Risk aware and feasibility aware

Negotiation/resolutoin of conflicting requirements

Shared understanding

Innovation

RE Problems

• Natural language problems

• Domain understanding

• Business needs not considered

• Complexity

• Incompleteness

• Inconsisency

• Incorrectness

• Over-completeness

• Limited user/stakeholder involvement

• Poor requirements mgmt

In an agile setting, an _____ and ______ RE process fits best

Iteraive

Explorative

Actor

External entities that interact with the system (human, hardware, external software)

Use Case

Set of actions defining interactions between an actor and system to achieve a goal

Associaiton

which actors the use case communicates with, including the actor that initiates the execution of the use case

(shown through a straight line connecing the actor and oval withe use case)

What is the purpose of a scenario?

Shows the goal of the user, setting of usage, some of the steps

Humans easily understand and relate to stories

What are the types of flows?

Basic flow: Required for every use case (happy day)

Alternative: Goal is achieved but in an alterate way

Exception: Goal is not achieved