{"id":23,"date":"2023-09-04T18:35:40","date_gmt":"2023-09-04T18:35:40","guid":{"rendered":"https:\/\/libraryresources.nse.org.ng\/setextbook\/chapter\/agile\/"},"modified":"2026-03-16T14:20:29","modified_gmt":"2026-03-16T14:20:29","slug":"agile","status":"publish","type":"chapter","link":"https:\/\/libraryresources.nse.org.ng\/setextbook\/chapter\/agile\/","title":{"raw":"Agile","rendered":"Agile"},"content":{"raw":"
\"Chapter<\/a><\/div>\n

Chapter 1\nAgile<\/h2>\nThis book is geared toward [pb_glossary id=\"788\"]Agile[\/pb_glossary], but there are other [pb_glossary id=\"793\"]software process models[\/pb_glossary]. Each has a different way of proceeding through the [pb_glossary id=\"790\"]software development life cycle (SDLC)[\/pb_glossary]. This chapter starts by describing Scrum, the SDLC, Agile, and a contrasting software process model called Waterfall. That is followed by a discussion of [pb_glossary id=\"791\"]Scrum[\/pb_glossary] (an Agile framework) and notable Agile methods.\n\nThis chapter will give you the flavor of Agile and Scrum rather than being a comprehensive guide. For more detailed information about topics introduced here, see the References section at the end of the chapter.\n

1.1 The Software Development Life Cycle<\/h1>\nThe software development lifecycle (SDLC) is the progression of a software project through five SDLC stages:\n
    \n \t
  1. Requirements<\/strong>: Figuring out and writing down what the software must do, how well, and under what limitations or constraints.<\/li>\n \t
  2. Design<\/strong>: Determining how the software\u2019s code will be structured and how users will interact with the software.<\/li>\n \t
  3. Implementation<\/strong>: Using the requirements and design to code the software.<\/li>\n \t
  4. Testing<\/strong>: Checking that the code was written without fault ([pb_glossary id=\"794\"]verification[\/pb_glossary]) and that the software is what the users or client wants ([pb_glossary id=\"795\"]validation[\/pb_glossary]).<\/li>\n \t
  5. Maintenance<\/strong>: Improving software\u2019s existing functionality and code.<\/li>\n<\/ol>\nThere are different ways to travel through the SDLC stages. Patterns of traveling through the stages are called software process models. Commonly, people compare the Agile software process model with the [pb_glossary id=\"792\"]Waterfall[\/pb_glossary] model.\n\nAgile, guided by the Agile Manifesto<\/em> (Beck et al., [pb_glossary id=\"332\"]2001[\/pb_glossary]<\/span>), moves through the SDLC approximately like in Figure 1.1.\n\n[caption id=\"attachment_98\" align=\"aligncenter\" width=\"1336\"]\"Three<\/a> Figure 1.1<\/strong> How Agile Projects Move through SDLC Stages[\/caption]\n\nNote<\/em>. The vertical lines represent development cycle boundaries. Planning (R,D) for the next development cycle starts during the previous cycle. R, requirements; D, design; I, implementation; T, testing; M, maintenance.\n\nAgile development cycles are relatively short and numerous. Releases are frequent and incremental. Each cycle, there\u2019s a little more working functionality. There are multiple ways to go about developing and managing software in an Agile way, such as by using the Scrum framework (Schwaber & Sutherland, [pb_glossary id=\"338\"]2020[\/pb_glossary]<\/span>) or Extreme Programming (XP) (Beck & Andres, [pb_glossary id=\"335\"]2004[\/pb_glossary]<\/span>; Wells, [pb_glossary id=\"340\"]2013[\/pb_glossary]<\/span>).\n\nWaterfall moves through the SDLC approximately like in Figure 1.2.\n\n[caption id=\"attachment_99\" align=\"aligncenter\" width=\"1246\"]\"Text<\/a> Figure 1.2<\/strong> How Waterfall Projects Move through SDLC Stages[\/caption]\n\nMovement is fairly linear and sequential. Each stage depends on the previous stage having been completed. Lots of documentation is produced.\n\nIronically, people often associate Waterfall with an article that describes Waterfall\u2019s major flaws. The second figure in Royce\u2019s ([pb_glossary id=\"337\"]1970[\/pb_glossary]<\/span>) article depicts the Waterfall model with seven stages and downward movement from one stage to the next, suggesting that movement to the previous stage is not allowed\u2014you can\u2019t swim up a waterfall. Later in the article, Royce suggests modifications to the Waterfall model, such as making and implementing a preliminary program design (then going back to the requirements stage as needed).\n\nWaterfall might not make sense for many software projects, but how about for building a bridge?\n

    1.1.1 Why Care about Agile, Other Software Process Models, and Software Engineering Methods?<\/h2>\n
    \n\nThe 2015 CHAOS report contains aggregate data about more than 25,000 software projects.\n\nSome findings about software projects<\/strong>:\n\n9% of Agile projects failed\n29% of Waterfall projects failed\n23% of large Agile projects failed\n42% of large Waterfall projects failed\n4% of small Agile projects failed\n11% of small Waterfall projects failed\n\n<\/div>\n