XP Requirements Engineering-Software Engineering-Lecture Slides, Slides of Software Engineering

Download XP Requirements Engineering-Software Engineering-Lecture Slides and more Slides Software Engineering in PDF only on Docsity! Software Requirements Specification a eEeEee ~ . ‘ _ ~ 7 SRS in XP docsity.com “Dilbert” on Extreme and Agile Programming EXTREME PROGRAMMING I CAN'T GIVE YOU ALL OF THESE FEATURES IN THE FIRST VERSION. AND EACH FEATURE NEEDS TO HAVE WHAT WE CALL A “USER STORY.” ifr2]o3 © 2002 United Feature Syndicate, Inc OKAY, HERE'S A STORY: YOU GIVE ME ALL OF MY FEATURES OR TLL RUIN YOUR LIFE. WE'RE GOING TO TRY SOMETHING CALLED EXTREME PROGRAM- MING. www.dilbert.com — scottadamaieotcom www.dilbert.com — scottadams®a0l.com FIRST, PICK A PARTNER. THE TWO OF YOU WILL WORK AT ONE COMPUTER FOR FORTY HOURS A WEEK. 1(3]0.3 ©2002 United Feature Syndicate, inc THE NEW SYSTEM IS A MINUTE OLD AND I ALREADY HATE EVERYONE. Cy Copyright 9 2803 United Feature Syndicate, Inc. 4-2 docsity.com Problems of requirements analysis  Stakeholders don’t know what they really want  Stakeholders express requirements in their own terms  Different stakeholders may have conflicting requirements  Organisational and political factors may influence the system requirements  The requirements change during the analysis process. New stakeholders may emerge docsity.com The requirements analysis process Requirements validation Domain understanding Prioritization Requirements collection Conflict resolution Classification Requirements definition and specification Process entry docsity.com CS428 4-7 Requirements Requirements should be specific, so you can tell whether you met them. precise as necessary, but no more Functional requirements inputs, outputs, and the relations between them in theory, can specify completely Non-functional requirements hard to specify, can’t specify completely •scalability •maintainability •portability •... •security •reliability •efficiency •usability docsity.com Functional requirements  Requirement: a desired relationship among phenomena of the environment of a system, to be brought about by the hardware/software machine that will be constructed and installed in the environment.  A specification describes machine behavior sufficient to achieve the requirement.  A specification is a restricted kind of requirement Lathe Operator Machine Required Behavior of lathe Specification Requirements docsity.com Functional requirements  Requirements define necessary objectives e.g. software must handle error states reasonably and effectively, and provide explicit feedback to the users.  Specifications Define How to Meet The Objectives list out all possible error states for a certain form, along with all of the error messages that should be displayed to the user. docsity.com CS428 4-12 Non-functional requirements Performance Must answer a query in 3 seconds Usability New user must be able to finish buying a book in 15 minutes 90% of users must say they like interface Maintainability New programmers should be able to fix first bug in two weeks on the job docsity.com User Stories User story is a short description of what the business or customer wants the software to do, written by the customer in the customer terminology without techno-syntax. docsity.com User Stories Index Cards  Usually written on index cards because easy to understand Pass around Tear up Prioritize  One and only one business feature Written by & focus on customer  Avoid details of specific technology, data base layout, and algorithms docsity.com Poor User Stories  Too vague and hard to Estimate Test  Defines implementation details  Customer doesn’t care about Tomcat or Dreamweaver docsity.com User Stories for Northwind Dap Shopping Cart Displ obi ¢ - Uses user id / paseword required +o Add Allow customer to look at order login. . staivs using their order Number. Kemove = : . ; Status * Customer Contact information for Display Sething up new aecounts. } ~ Processing Update, = Shipped | Browse Catalog _ ~ a) fh ' [Display Order Contirmatian a Display Categories / Sub “Cateqones Provide feedback Confirm order with Untl drill down +o an item " fer wi an order number Display only active items. — Web-based ~ mail Search for Product Dp Splay Order History a Search the Title / Produce Name Display all orders for a given Customer. Descri prion 3-20 3 docsity.com Quick High-Level Design Flow Login Order Product Screen Flow Product List Product Detail | Admin My Acct Cart Admin My Acct Cart Admin My Acct Cart | Lil —| Admin My Acct Cart — | (Creckout) (Cont, Order Contirmation Order | teimin My Acet Cart — | Admin My Acct Cart (Gare) Gori) 3-21 docsity.com User Story Estimating &Planning Game  Estimating Estimates are in Story Points 1 story point = 1 ideal day  Planning Game Prioritization of User Stories Priority is from 1 to n, not high, medium, low. Velocity Determination (No. of Devs/Load Factor✕ Iteration Length in Business Days E.g. for • 8 developers • 2-week iteration (10 business days) • load factor=4 (as developers spend time not coding (meetings, email, pair programming) Iteration velocity (#story pts team can complete)= (8/4 X 10) = 20 docsity.com Individual’s Velocity  Here is the formula for calculating the velocity of an individual:  No. of Hours in Workday ✕ Length of Iteration/Load Factor (Truncated) = Individual Velocity  The length of the iteration is in business days. The load factor accounts for other, non development activities. The individual velocity is in ideal hours.  For example, the following uses an 8-hour workday with a 2-week iteration and a load factor of 4:  8 ✕ 10/4 = 20  The result is 20 ideal hours in the iteration for the developer. docsity.com Story Selection Velocity of a single iteration (4/3 ✕ 10) = 13 Two week Iteration docsity.com User Stories Review fone __A Story card SS Short descriptive Cup of Tea title ——_ thing wanted I want a cup of tea so that | feel refreshed business benefit expected Developers’ estimate —5 minutes Back Ac ce pta nce tests Action Result Thermometer shows Put thermometer in cup evemaOlee cits Drink liquid in cup Tastes like tea docsity.com