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SDLC stands for Software Development Lifecycle and it is the process of developing information system with proper analysis, design, implementation and maintenance. SDLC is said to be equal to layer two of open systems interconnection or OSI model of network communication. This level of protocol assures proper flow of data from one level to another.

In any mainframe networks, host mainframe is considered as primary workstation and other devices are known to be secondary workstations. Therefore, SDLC uses primary station and secondary station for its mode of communication. Secondary station has its own address and they are attached to common port, which is known as multi point of multi drop arrangement. SDLC is used for point-to-point communication. This is made use for many remote communications.

There are many major things associated with SDLC. It is considered as the basis of standard data link protocol in ISO, High-level data link control. It also became one of the variations in HDLC. SDLC are efficient protocols and they are used in close network with its own private lines.

Phases in Software Development Lifecycle

Testing phase has much importance in SDLC due to a major role in debugging and error correction. The phases of SDLC is being followed in both testing and development cycle of any software application. Here are the phases of SDLC that is being followed:

1)      Requirements gathering and analysis: Under this phase, proper requirements of project are gathered. All close functions are brought in to focus. All kinds of requirements and analysis of user requirement are done in this phase.

1)      System design: This is the next phase in SDLC where a rough system design is made. With all data and information being gathered, a system design is made.

2)      Development: This is the next phase after system design when development of project is made. According to design, proper coding is done to gain that design. Programming language might be selected according to the project.

3)      System testing: Just after development phase, testing is carried out to know the outcome of application. Testing is made to know the actual result and the expected result.

4)      Operations and maintenance: This is the final stage of SDLC, where the software that is being developed is being distributed to end users who are responsible for maintaining and using it for proper operations. The software that is being developed must be open to any changes being made in coding.



Fig: Phases in Software Development Lifecycle

Major Importance of Testing in SDLC

Some major things are necessary in SDLC phase.

1)      Identification of bugs and defects: Testing phase is one phase that determines the bugs and errors in the application. These bugs can be at unit level or system level. With so many testing phases, you get to keep away from any kind of bugs that may be affecting your application.

2)      Information to stakeholders and reputation of company: With the help of testing phase, it helps you to know the state of product and service quality. The stakeholders get good information through testing phase about service quality too.

3)      Improvement in product quality: As testing is a phase that helps in knowing the actual outcome and the expected outcome. Surely, it can help you to improve your product quality. With proper testing done, you come out of errors and develop perfect software application for the users.

4)      Technical importance: In any SDLC lifecycle, testing phase is important for technical aspect, as it has to come out with best technically sound application.

5)      To get ahead of any competitive developers: Perfect testing tools and methods help you and your application to grow up in market and keep away your competitors. With getting away in all phases of testing, you develop more sound, safe and secure software application.

6)      Keep away any hazards: When you develop any software, testing plays an important part. When you give your software without any testing then it may be hazardous to the users who are using it. To keep everyone away from any hazard, it is necessary that you go under all testing phases.

7)      Improved quality: Proper tested software gives you more confidence of coming up with great software. Secondly, it improves quality of your software application as continuous and all kinds of testing modes have made a secure and safe application that can be used by the end users.

8)      Verification and validation: One of the main aims of testing phase in SDLC is for verification and validation. Testing is a phase that can serve as a metrics as it is used heavily in V&V method. Based on the result, you could come out with comparison between qualities amongst different products.

9)      Reliability estimation: This is yet another important factor that is determined by the testing phase. If your software application has gone through all small level like unit testing and major testing like regression testing and all, then sure it is a reliable application. Hence testing determines reliability of your software application. Testing may serve as the best statistical method that defines operational testing on application resulting in a reliable software product.

10)  Economic importance: A well-tested software application will have good economic impact. This is because any one would love to go with reliable and trusted application in market.

There are many kinds of SDLC models and each of these models makes use of testing phase. Hence, this makes testing a very important part in any software development life cycle. With unit testing, integration tests, system testing, regression tests and user acceptance testing and major types of testing, helps any developer to come up with a reliable and trusted web application that can be useful. Testing also follows its own lifecycle like test analysis, test plan, test design and test execution



Fig: Major importance of testing in SDLC

Role of testing in SDLC

1)      Inception phase: A test engineer understands the need of project in this phase.

2) Elaboration phase: In this phase, any tester tries to understand how the project is being developed. Requirements are easily made.

3)      Construction phase: Developers play an important role and they help developing design of the software. Tester has to know that all requirements are being traced through test cases. System testing and integration testing is necessary in this phase.

4) Transition phase: In this phase if any defects or bugs are found then they are re tested and it goes under regression testing phase. With regression testing, reliable products come out.

With help of testing in SDLC, any basic product is transformed in to a strong and reliable product. This
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