Spiral Model | Software Engineering

  Spiral Model

The spiral model is also known as spiral lifecycle model.

 This model of development combines the feature of the prototype and waterfall model

 A spiral model is divided into a number of framework activities, also called task Regions.

 Typically, there are six task regions. Software project repeatedly passes though these phases

in iterations called spiral.

 Diagram of spiral model that contains six task regions:

1) Customer communication:

• In this tasks required to establish effective communication between developer and

customer.

2) Planning:

• In this tasks required defining resources, timelines, and other project related

information.

• Requirements are studied and gathered

• Review and walkthroughs to streamline the requirements.

• Finalize the list of documents.

• The project is review and a decision made whether to continue with a further loop of

the spiral.

• If it is decided to continue, plans are drawn up for the next phase of the project.

3) Risk analysis

• In this tasks required to assess both technical and management risks.

• In the risk analysis phase a process is undertaken to identify risk and alternate

solutions.

• A prototype is produced at the end of the risk analysis phase.

• If any risk is found during the risk analysis then alternate solutions are suggested

and implemented.

4) Engineering

• In this phase software is developed, along with testing at the end of the phase.

• Actual development and testing is done if the software takes place in this phase.

• It include coding, test case and test results, test summary report

5) Construction and release

• It is requires to construct, test, install, and provide user support (e.g., documentation

and training).

6)Customer evaluation

• Customers evaluate the software and provide their feedback and approval.

• Features implemented document

 When to use Spiral model:

• When the project is large.

• Where software needs continuous risk evaluation.

• When costs and risk evaluation is important.

• For medium to high-risk projects

• Users are unsure of their needs

• Requirements are complex and require continuous classification.

• New product line.

 Advantages of Spiral model:

• Risk evaluation is proper.

• High amount of risk analysis hence, avoidance of Risk is enhanced.

• Good for large and critical projects.

• Strong approval and documentation control.

• More and more features are added in a systematic way.

• Software is produced early in the software life cycle.

 Disadvantages of Spiral model:

• It is costly for small model.

• Risk analysis is important phase so requires expert people.

• Project’s success is highly dependent on the risk analysis phase.

• Spiral may go infinitely.

• It is suitable for larger project and not beneficial for smaller projects.