1. What is an Application Development Life Cycle

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Like humans, computer projects also have a life cycle of their own and each cycle goes through several natural stages. The life cycle of an application-development project is usually like the following:

1. Feasibility Study
   
   In this cycle also known as a phase, you will make decision like whether to undertake a new computer project or not. These decision can be made by answering questions like
   
   
   • What business problem are you going to solve using your new system?
   • What is the improvement or the advantage the new system has over the old system?
   • If there are any improvements or advantages, can they be measured?
   • Is it possible to create the new system?
   • How much will it cost for you to design, develop and implement the new system?
   • What time period will you take for the completion of your system?
   The final answers for these will give you an idea of how your project charter will look like. You then will be able to define the scope of the project, user requirements, budget constraints etc.
2. Analysis
   
   This is the process in which you will decide exactly what your computer system has to do. The best practice is to document the existing system that the new system is to replace. This has to be done even if the existing system is a manual one and is completely filled with inefficiency and errors.
   
   Using this, you must create a specification for the new system in which it defines what the new system will do. At this stage you do not have to document how the new system will work to replace the old system.
3. Design
   
   During this phase you should create a plan for the implementation phase. That how you will implement the specifications for the new system that resulted from the Analysis step. The design phase mainly focuses on how the new system will work.
4. Implementation
   
   This is the phase where the programs that you make for the new system are coded and tested. The hardware required to support the new system is also purchase and installed in this phase. The database required for the new system are also defined and loaded here.
5. Acceptance Testing
   
   It is also known as functional testing, black-box testing, QA testing, application testing, confidence testing, final testing, validation testing, or factory acceptance testing. During this phase all the modules of the new system are checked and made sure that they work well individually and when integrated as they should do according to specifications
6. Production
   
   If all the testing is passed according to the specifications and is acceptable, the new system is put into production. It during this phase that the actual users of the new system start to use it.
7. Maintenance
   
   This is the phase where the maintenance of the new system is started after it has gone to the Production phase. During this phase all errors that were not detected during the Implementation and Acceptance phases are corrected. As the users of the new system work with the system, they will come to realize that what they actually wanted was not provided in the new system, so they might ask you for enhancement features to be incorporated to the new system.
   
   When adding new enhancements as per user’s requests, you should take extra care so that these actions do not create more problems than they solve.

The best Project Managers always try to lead their projects through these steps, one at a time, perfecting each step as they proceed. These phases may sometimes overlap with each other, because the modern development methods are more into the iterative process.

Quality needs to be built into each phase of development, and shouldn’t be tacked on to the end as an afterthought through a process called Quality Assurance. Documentation of the system is also a vital phase and it should be done constantly as the system is developed, to minimize confusion.

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Table of Contents

» Chapter 1 - What is an Application Development Life Cycle
Chapter 2 - What is an Application Design
Chapter 3 - What are the Layered Architectures
        Chapter 3.1 - Two-Layer Architecture
        Chapter 3.2 - Three-Layer Architecture
        Chapter 3.3 - Model View Controller
Chapter 4 - How to design User Interface using ASP.NET 2.0
Chapter 5 - How to design a Relational Database
        Chapter 5.1 - Step 1 – Create a charter for the database
        Chapter 5.2 - Step 2 – Make a list and double check it
        Chapter 5.3 - Step 3 – Add Keys
        Chapter 5.4 - Step 4 – Normalize the Database
                Chapter 5.4.1 - First Normal Form - 1NF
                Chapter 5.4.2 - Second Normal Form – 2NF
                Chapter 5.4.3 - Third Normal Form – 3NF
        Chapter 5.5 - Step 5 – Denormalize the Database
        Chapter 5.6 - Step 6 – Use legal SQL names
        Chapter 5.7 - Step 7 – Draw an ERD
Chapter 6 - How to design Objects
Chapter 7 - How to design an UML Class Diagram
        Chapter 7.1 - Drawing Classes
        Chapter 7.2 - Drawing Arrows

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