CSC 423 Chapter 03, Fall 2011

1 Chapter 3  Agile Development 2 The Manifesto for Agile Software Development “We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value: • Individuals and interactions over processes and tools • Working software over comprehensive documentation • Customer collaboration over contract negotiation • Responding to change over following a plan That is, while there is value in the items on the right, we value the items on the left more.” Kent Beck et al 3 What is “Agility”?  Effective (rapid and adaptive) response to change  Effective communication among all stakeholders  Drawing the customer onto the team  Organizing a team so that it is in control of the work performed Yielding …  Rapid, incremental delivery of software 4 Agility and the Cost of Change 5 An Agile Process  Is driven by customer descriptions of what is required (scenarios)  Recognizes that plans are short-lived  Develops software iteratively with a heavy emphasis on construction activities  Delivers multiple ‘software increments’  Adapts as changes occur 6 Agility Principles - I 1. Our highest priority is to satisfy the customer through early and continuous delivery of valuable software. 2. Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage. 3. Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale. 4. Business people and developers must work together daily throughout the project. 5. Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done. 6. The most efficient and effective method of conveying information to and within a development team is face–to–face conversation. 7 Agility Principles - II 7. Working software is the primary measure of progress. 8. Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely. 9. Continuous attention to technical excellence and good design enhances agility. 10. Simplicity – the art of maximizing the amount of work not done – is essential. 11. The best architectures, requirements, and designs emerge from self–organizing teams. 12. At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly. 8 Human Factors  the process molds to the needs of the people and team, not the other way around  key traits must exist among the people on an agile team and the team itself:  Competence.  Common focus.  Collaboration.  Decision-making ability.  Fuzzy problem-solving ability.  Mutual trust and respect.  Self-organization. 9 Extreme Programming (XP)  The most widely used agile process, originally proposed by Kent Beck  XP Planning  Begins with the creation of “user stories”  Agile team assesses each story and assigns a cost  Stories are grouped to for a deliverable increment  A commitment is made on delivery date  After the first increment “project velocity” is used to help define subsequent delivery dates for other increments 10 Example of User Stories:  As a user, I want to search for contacts so I can message them.  As a customer, I want to search for product items so I can buy them.  As an employer, I want to post a job on the website so people can apply for it. 11 NOT User Stories:  Implement contact list view ContactListView.java  Define the product table database schema  Automate the job posting algorithm 12 Example – User Story  As a job company, I can use my credit card so I can pay for postings.(A job company can pay for posting with a credit card.) Note: Accept Visa, MasterCard, American Express. Test: (on the back of the story card) Test with Visa, MasterCard and American Express (pass) Test with Diner’s Club (fail) Test with good, bad and missing card ID numbers. Test with expired cards. Test with over $100 and under $100. 13 Example – User Story & Test As a Creator, I want to upload a video from my local machine so that any users can view it. Note: … Test:  Click the “Upload” button. • Specify a video file to upload. • Check that .flv, .mov, .mp4, .avi, and .mpg extensions are supported. • Check that other filetypes aren’t able to be uploaded. • Check that files larger than 100MB results in an error. • Check that movies longer than 10 mins result in an error.  Click “Upload Video”.  Check that progress is displayed in real time. 14 Class Activity In groups of 2 on paper: Write down 3 user stories for an online music store (such as the music part of iTunes) 15 Extreme Programming (XP)  XP Design  Follows the KIS principle  For difficult design problems, suggests the creation of “spike solutions”—a design prototype  Encourages “refactoring”—an iterative refinement of the internal program design  XP Coding  Recommends the construction of a unit test for a store before coding commences  Encourages “pair programming”  XP Testing  All unit tests are executed daily  “Acceptance tests” are defined by the customer and executed to assess customer visible functionality 16 Class Activity  In groups of 2, write your names on a piece of paper: Write three tests for banking software that manages deposits at an ATM E.g., “Ensure that the customer does not leave his or her card in the machine” 17 Extreme Programming (XP) unit test continuous integration acceptance testing pair programming Release user stories values acceptance test criteria iteration plan simple design CRC cards spike solutions prototypes refactoring software increment project velocity computed 18 Adaptive Software Development  Originally proposed by Jim Highsmith  ASD — distinguishing features  Mission-driven planning  Component-based focus  Uses “time-boxing” (See Chapter 24)  Explicit consideration of risks  Emphasizes collaboration for requirements gathering  Emphasizes “learning” throughout the process 19 Adaptive Software Development adaptive cycle planning uses mission statement project constraints basic requirements time-boxed release plan Requirements gathering J AD mini-specs components implemented/ tested focus groups for feedback formal technical reviews postmortems software increment adjustments for subsequent cycles Release 20 Dynamic Systems Development Method  Promoted by the DSDM Consortium (www.dsdm.org)  DSDM—distinguishing features  Similar in most respects to XP and/or ASD  Nine guiding principles • Active user involvement is imperative. • DSDM teams must be empowered to make decisions. • The focus is on frequent delivery of products. • Fitness for business purpose is the essential criterion for acceptance of deliverables. • Iterative and incremental development is necessary to converge on an accurate business solution. • All changes during development are reversible. • Requirements are baselined at a high level • Testing is integrated throughout the life-cycle. 21 Dynamic Systems Development Method DSDM Life Cycle (with permission of the DSDM consortium) 22 Scrum  Originally proposed by Schwaber and Beedle  Scrum—distinguishing features  Development work is partitioned into “packets”  Testing and documentation are on-going as the product is constructed  Work occurs in “sprints” and is derived from a “backlog” of existing requirements  Meetings are very short and sometimes conducted without chairs  “demos” are delivered to the customer with the time- box allocated 23 Scrum Scrum Process Flow (used with permission) 24 Crystal  Proposed by Cockburn and Highsmith  Crystal—distinguishing features  Actually a family of process models that allow “maneuverability” based on problem characteristics  Face-to-face communication is emphasized  Suggests the use of “reflection workshops” to review the work habits of the team 25 Feature Driven Development  Originally proposed by Peter Coad et al  FDD—distinguishing features  Emphasis is on defining “features” • a feature “is a client-valued function that can be implemented in two weeks or less.”  Uses a feature template • <action> the <result> <by | for | of | to> a(n) <object>  A features list is created and “plan by feature” is conducted  Design and construction merge in FDD 26 Examples of features for an e-commerce application:  Add the product to a shopping cart  Display the technical-specifications of the product  Store the shipping-information for the customer 27 Feature Driven Development Reprinted with permission of Peter Coad