Software Development Life Cycle

Software Development Life Cycle

1. WATERFALL LIFE CYCLE MODEL

   • The term software development life cycle model is a way of describing the planning, designing, coding, and testing of a software system, as well as the method in which these steps are implemented. A variety of life cycle models exist, but they all include the same constituent parts. All life cycle models take a project through several primary phases: a requirements-gathering phase, a design phase, a construction or implementation phase, and a testing phase. Figure 4-1 provides a simplified illustration of the general software development life cycle model.
   • Requirements
     • During the requirements-gathering phase, the needs of the company are outlined. Managers and users (and in some cases, clients) make their “wish-lists” about what they would like the software to do. Analysts ask questions about the intended use of the software, what type of data will be processed, how the software should handle the data, and how the data can be accessed once in the system.
     • Design
       • In the design phase, the results of the requirements-gathering phase are translated into a software design plan. Focus shifts from the system's results to the way in which those results will be achieved and how the ideas of the requirements-gathering phase are accomplished. Designers consider many different criteria, from the hardware and operating system platform that hosting the software to the way subsystems will communicate with each other
       • Implementation and Unit Testing
         • All the units developed in the implementation phase are integrated into a system after testing of each unit. The software designed, needs to go through constant software testing to find out if there are any flaw or errors. Testing is done so that the client does not face any problem during the installation of the software.
         • Integration and System Testing
           • in this stage all the files and functions of the program are tested so it is possible to verify if the system works or not
           • Operation
             • en esta etapa se identifica y corrige cualquier problema que se pueda presentar teniendo siempre el sistema en operacion 

2. SPIRAL LIFE CYCLE MODEL

   • The Spiral model is represented by a spiral passing through four quadrants, which represent the four phases of development. Requirements gathering is performed in the planning phase. During the risk analysis phase, a formal process is undertaken to identify alternative courses of action and their relative risks. A prototype is also developed during this phase. Software is coded and tested during the engineering phase. During the evaluation phase, the customer has an opportunity to evaluate the output before the project proceeds to the next spiral. Notice that the angular component represents the progress in the current spiral, and the radius represents the project cost.
   • PLANNING
     • RISK ANALYSIS
       • ENGINERING
         • EVALUATION
           • CUSTOME EVALUATION
             • PROJECT COST
         • CODING
           • TESTING
       • RISK ANALYSIS
         • PROTOTYPING
     • REQUIREMENTS GATHERING

3. V-SHAPED LIFE CYCLE MODEL

   • Like the Waterfall model, the V-Shaped life cycle model provides a sequential path of discrete phases that must each be completed before development proceeds to the next phase. The phase test plans are developed during each level of development, and once coding is completed, the tests are conducted.
   • REQUERIMENTS
     • During the requirements-gathering phase, the needs of the company are outlined. Managers and users (and in some cases, clients) make their “wish-lists” about what they would like the software to do. Analysts ask questions about the intended use of the software, what type of data will be processed, how the software should handle the data, and how the data can be accessed once in the system.
     • HIGH LEVEL DESING
       • Systems design is the phase where system engineers analyze and understand the business of the proposed system by studying the user requirements document. They figure out possibilities and techniques by which the user requirements can be implemented. If any of the requirements are not feasible, the user is informed of the issue. A resolution is found and the user requirement document is edited accordingly
       • INTEGRATION TEST PLANING
         • INTEGRATION TESTING
       • LOW LEVEL DESING
         • in this phase some details that are missing in the high level design are corrected or added.
         • UNNIT TEST PLANNING
           • UNIT TESTING
         • IMPLEMENTATION
           • phase is, again, where all coding takes place. Once coding is complete, the path of execution continues up the right side of the V where the test plans developed earlier are now put to use.
   • SYSTEM TESTING
   • SYSTEM TEST PLANNING
     • you are planning to do the system to start with the design of the program

4. INCREMENTAL LIFE CYCLE MODEL

   • The Incremental life cycle model builds an iterative approach into the Waterfall model. Development projects are divided into several smaller, more manageable iterations. Each iteration passes through a mini-Waterfall process. Requirement, design, implementation and testing phases are completed for each iteration.
   • REQUERIMENTS
     • During the requirements-gathering phase, the needs of the company are outlined. Managers and users (and in some cases, clients) make their “wish-lists” about what they would like the software to do. Analysts ask questions about the intended use of the software, what type of data will be processed, how the software should handle the data, and how the data can be accessed once in the system.
     • DESING
       • In the design phase, the results of the requirements-gathering phase are translated into a software design plan. Focus shifts from the system's results to the way in which those results will be achieved and how the ideas of the requirements-gathering phase are accomplished. Designers consider many different criteria, from the hardware and operating system platform that hosting the software to the way subsystems will communicate with each other
       • IMPLEMENTATION AND UNIT TESTING
         • All the units developed in the implementation phase are integrated into a system after testing of each unit. The software designed, needs to go through constant software testing to find out if there are any flaw or errors. Testing is done so that the client does not face any problem during the installation of the software.
         • Integration and System Testing
           • in this stage all the files and functions of the program are tested so it is possible to verify if the system works or not
           • OPERATION
             • en esta etapa se identifica y corrige cualquier problema que se pueda presentar teniendo siempre el sistema en operacion 

5. SOFTWARE DEVELOPMENT LIFE CYCLE MODEL

   • The term software development life cycle model is a way of describing the planning, designing, coding, and testing of a software system, as well as the method in which these steps are implemented. A variety of life cycle models exist, but they all include the same constituent parts. All life cycle models take a project through several primary phases: a requirements-gathering phase, a design phase, a construction or implementation phase, and a testing phase. Figure 4-1 provides a simplified illustration of the general software development life cycle model.
   • Requirements
     • During the requirements-gathering phase, the needs of the company are outlined. Managers and users (and in some cases, clients) make their “wish-lists” about what they would like the software to do. Analysts ask questions about the intended use of the software, what type of data will be processed, how the software should handle the data, and how the data can be accessed once in the system.
     • Design
       • In the design phase, the results of the requirements-gathering phase are translated into a software design plan. Focus shifts from the system's results to the way in which those results will be achieved and how the ideas of the requirements-gathering phase are accomplished. Designers consider many different criteria, from the hardware and operating system platform that hosting the software to the way subsystems will communicate with each other
       • Implementation
         • In the implementation phase, the results of the design phase are translated into program code. Software that does not meet the needs of the company is wasteful. During this phase the programmers should make it their central goal to fulfill the requirements of the company and to meet the design outlined in the design phase.
         • Testing
           • In the testing phase, the results of the implementation phase are run through a series of tests to verify that it functions and that it meets goals of the requirements phase. A testing plan is created to describe the unit tests and system tests that will be performed. Unit testing is performed on individual software components. The process of integration brings together all the software components to create a complete system. System testing is performed on the software system as a whole.