The Software Development Life Cycle

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The Software DevelopmentLife Cycle
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Today We Will

• Go over the different phases of the software
  development life cycle.
• Introduce the various tools used in each phase.
  These tools will be the focus of the course.
• Break up into teams to discuss the presentations
  and the final projects.

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History of SDLC Models

• Once upon a time, software development consisted
  of a programmer writing code to solve a problem
  or automate a procedure.
• Nowadays, systems are so big and complex that
  teams of architects, analysts, programmers,
  testers and users must work together to create
  the millions of lines of custom-written code that
  drive our enterprises.
• Note There are different types of software
  development that call for different development
  strategies. This class focuses on the
  development of large-scale enterprise systems.
  See pg. 33 in book to see the differences in
  software development.

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How Software Engineering has Changed

• Seven factors that have altered software
  engineering practice
• Criticality of time-to-market for commercial
  products
• Shifts in the economics of computing lower
  hardware costs and greater development and
  maintenance costs
• Availability of powerful desktop computing
• Extensive local and wide-area networking
• Availability and adoption of OO technology
• GUIs using windows, icons, menus and pointers
• Unpreditability of the waterfall method of
  software development (see. Pg. 49 in book)
• To manage this, a number of system development
  life cycle (SDLC) models have been created
  waterfall, fountain, spiral, build and fix, rapid
  prototyping, incremental, and synchronize and
  stabilize.
• The book covers these models in more detail.

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What Is the SDLC?

• Definition from ComputerWorldThe software/system
  development life cycle (SDLC) is the overall
  process of developing information systems through
  a multi-step process from investigation of
  initial requirements through analysis, design,
  implementation and maintenance.
• There are many different models and
  methodologies, but each generally consists of a
  series of similar defined steps or stages.

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Phases of the SDLC

• Feasibility study and project planning.
• Requirements definition and systems analysis.
• Systems and program design.
• Implementation.
• Unit testing.
• Integration and system testing
• Acceptance, installation, deployment.
• Maintenance.

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Phases of the SDLC

• Over the years, one thing that has become
  apparent to most software engineers is that
  requirements grow and change throughout the
  process and beyond. They are not static.
• This calls for considerable feedback and
  iterative consultation with the users. Often you
  will find the need to go back and reiterate
  earlier stages a number of times as the project
  progresses.
• In the SDLC process, some activities obviously
  can't start before others -- such as you need a
  design before you can start coding but there is
  a considerable overlap between some of the
  activities.
• Many argue that the most effective model for
  dealing with todays systems development is the
  incremental model.
• The incremental model divides the product into
  builds, where sections of the project are created
  and tested separately. This approach will likely
  find errors in user requirements quickly, since
  user feedback is solicited for each stage and
  because code is tested sooner after it's written.
  
• This method also allows many teams to work
  efficiently in parallel. Teams can do successive
  compilations (called builds) of the entire
  project, bringing together all the current
  components.

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Tools Used in Phases of SDLCProject Planning

• Feasibility study and project planning
• In this phase, the project manager establishes a
  high-level view of the intended project and
  determines its goals.
• The software engineer uses his/her technical
  expertise to determine the feasibility of the
  desired goals and to give cost/time estimates.
• Usually the project manager and the software
  engineer(s) meet with the users to generate a
  high-level project plan. (see pg. 118 in book)
  Gantt charts are often used to track progress in
  the project plan. (see pg. 88)
• As requirements are gathered and specific tasks
  assigned, this project plan is refined.
• Popular tools used in this phase
• Microsoft project is the industry standard for
  maintaining project plans. We will not use this
  tool in class for two reasons
• This phase of the SDLC is really the
  responsibility of the project manager, not the
  software engineer, although sometimes the
  engineer is the project manager.
• MS project is very expensive.
• You can keep track of project plans with other
  tools (even a word doc).

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Tools Used in Phases of SDLCRequirements
Gathering

• Requirements definition and analysis
• In this phase, the SE refines project goals into
  defined functions and operations for the intended
  application. He/she constantly analyzes end-user
  information needs and transforms this information
  into models used by the programmers.
• UML is the standard modeling language used for OO
  system design. It is a very powerful modeling
  language and we could spend several semesters
  just talking about UML alone. We will only learn
  the basics.
• Popular tools used in this phase
• Rational rose, TogetherJ, EclipseUML.
• We will use EclipseUML for several reasons
• It is free, open software that is integrated with
  the IDE we will use.
• It is easier to learn than some of the other
  tools.

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Tools Used in Phases of SDLCSystem and Program
Design

• System and program design.
• System and program design are slightly different.
• In system design, the engineer designs the system
  components and how they will interact. This
  includes the presentation layer pieces (e.G.
  Screen layouts), the business logic layer pieces
  (business rules), and the data layer pieces (data
  access processes). The SE will determine what
  technologies should be used in each layer.
• Program design is system design at a finer level.
  Here the flow and structure of the actual
  program code is specified. For example, senior
  programmers/analysts will take the UML model and
  write pseudo-code detailing the classes, methods,
  interfaces, package design, etc. More junior
  programmers will take this pseudo-code and
  transform it into actual code (e.g. with java).
• Popular tools used in this phase
• Visio is a very popular tool for drawing flow
  charts and etc. For program design.
• Rational rose, TogetherJ, and EclipseUML are
  excellent resources for class diagrams. They all
  have the ability to transform changes to a UML
  model into code and vice-versa. We will use
  EclipseUML for this phase.

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Tools Used in Phases of SDLCImplementation

• Implementation
• This is where the real code is written based on
  the system and program design.
• IDEs (Integrated Development Environments)
  provide many helpful tools that assist
  programmers in this phase of development.
• Examples of these views include
• Varying views, debuggers, code completion, code
  organization, color schemes, and built-in
  plug-ins to help with other phases.
• Application Servers are needed to run servlets
  (Javas version of server-side program). The
  engineer will write code in the IDE for objects
  that will execute in the application server.
• Source code repositories are tools used to manage
  source code among several developers. They allow
  developers to check code out (preventing other
  developers from modifying that program). They
  also maintain version control allowing developers
  to see what changes were made by other developers.

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Tools Used in Phases of SDLCImplementation
(cont.)

• Popular tools used in this phase
• IDEs
• Eclipse, Visual Café, Visual Age, JDeveloper,
  Kawa
• We are going to use Eclipse, which is shareware
  from the Jakarta project. Eclipse is an IDE that
  has many plug-ins for the other tools we will be
  using.
• Application Servers
• WebLogic, WebSphere, Tomcat
• Although WebLogic and WebSphere control most of
  the market in larger companies, most smaller
  companies use Tomcat, which is shareware from the
  Jakarta project. All app servers vary in
  different respects, but almost all work the same
  way for basic functionality. So, by learning
  one, it is easier to learn the others.
• We will use Tomcat because it is an industry
  standard, it is easier to work with than most app
  servers, and it is free.
• Source code repository and version control
  systems
• CVS, ClearCase, PVCS, etc.
• We are going to use CVS, which is also from the
  Jakarta project. CVS is an industry leader in
  SCM tools and is shareware.

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Tools Used in Phases of SDLCTesting

• Testing
• Testing is an extremely important part of system
  development. Many companies have teams dedicated
  to testing and QA alone.
• There are different levels of testing that are
  needed throughout the SDLC.
• Unit testing
• This includes the testing of individual
  components. You have complete control over the
  test data and test cases and you run the tests
  yourself.
• Integration testing
• In this stage of testing, the SE often
  collaborate with a small number of other
  developers to test the integration of various
  system components.
• System testing.
• Brings all the pieces together into a special
  testing environment, then checks for errors, bugs
  and interoperability. These tests are often
  performed by a QA team.
• Popular tools used in this phase
• JUnit is used for unit and integration testing.
• This is a very popular tool in the J2EE world.
  It is free shareware from the Jakarta project.
  It has the ability to set up testing plans for
  individual components including regression
  testing.
• We will use this for our unit and integration
  testing.

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Tools Used in Phases of SDLCDeployment

• Delivery and Deployment
• This is the final stage of initial development,
  where the software is put into production and
  runs actual business.
• This part of the project is most often done by a
  build engineer, but software engineers should be
  familiar with the deployment tools used by the
  build engineer.
• The SE will often use the same tool for
  development and testing.
• Popular tools used in this phase
• Ant, Make
• We will use Ant, a shareware tool from the
  Jakarta project.
• It is an industry-standard in the OO development
  community.
• It is free.
• It is easier to use than Make.
• It is integrated with Eclipse.

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Tools Used in Phases of SDLC

• Maintenance
• What happens during the rest of the software's
  life changes, correction, additions, moves to a
  different computing platform and more. This, the
  least glamorous and perhaps most important step
  of all, goes on seemingly forever.
• Most junior developers start here to learn the
  systems.
• Popular tools used in this phase
• All of the tools above