Sdlc models
- 1. SOFTWARE DEVELOPMENT LIFE CYCLE MODELS: SUBMITTED TO: SUBMITTED BY: MRS. M.ANITHA V.KARTHIK. B.SC(C.S) SHINE TRAINER, SHINE TRAINEE, ASPIRE SYSTEMS. ASPIRE SYSTEM.
- 2. SDLC(SOFTWARE DEVELOPMENT LIFE CYCLE): It is also called as software development process. SDLC is a process which is used to develop, design a software and also modify the software which can be used mostly in the software industry. SDLC consists of detailed plan describing how to develop, replace, maintain modify the software. The life cycle defines to improve the quality of the software and overall description process. ISO/IEC 12207 is an international standard for software development life cycle. Some of the stages of the softwarwe development life cycle is as follows ▪ Planning and Requirement Analysis ▪ Defining Requirements ▪ Designing the Product Architecture ▪ Building or Developing the Product ▪ Testing the Product ▪ Deployment in the Market and Maintenance SDLC MODELS: There are various software development life cycle models defined and designed which are followed during the software development process. They are as follows. ▪ Waterfall model ▪ Iterative model ▪ Spiral model ▪ V-model ▪ Big bang model ▪ RAD model ▪ Agile model.
- 3. WATERFALL MODEL: Waterfall model was the first SDLC model to be used widely in software engineering to ensure sucessfull of the project. Waterfall model is a continuous process so that the process cannot able to modify the software by backtracking the processs. It is a classic life cycle model. Each process is completed before next starts. APPLICATION FOR WATERFALL: ➢ Requirements are very well documented, clear and fixed. ➢ Product definition is stable. ➢ Technology is understood and non complex ➢ There are no ambiguous requirement. ➢ Amble resources with reqiured expertise are available to support the product. ➢ The project is short. ADVANTAGES OF WATERFALL: ➢ Simple and easy to understand and use. ➢ Easy to manage due to rigidity of the model. ➢ Phases are processed and completed one at a time. ➢ Works well for smaller projects where requirements are very well understood. ➢ Process and results are well documented. ➢ Easy to arrange tasks. DISADVANTAGES OF WATERFALL: ➢ You cannot go back a step if the design phase has gone wrong, things can get very complicated in the implementation phase. ➢ High amounts of risk and uncertainty. ➢ Not a good model for complex and object-oriented projects. ➢ Poor model for long and on-going projects. ➢ Not suitable for the projects where requirements are at a moderate to high risk of changing.
- 4. ITERATIVE MODEL: Iterative life cycle model starts with a simple set of software requirements and begin to implement and after again iteratively enhances the evolving versions until the full system is implemented. At each iteration, design modification are made and new functional capabilities are added. For each iteration it must review the software. APPLICATION FOR ITERATIVE: ➢ Requirements of the complete system are clearly defined and understood. ➢ Major requirements must be defined however, some functionalities or requested enhancements may evolve with time. ➢ There is a time to market constraint. ➢ A new technology is being used and is being learnt by the development team while working on the project. ➢ Resources with needed skll sets are not available and are planned to be used on contract basis for specific iterations. ➢ There are some high-risk features and goals which may change in the future. ADVANTAGES OF ITERATIVE: ➢ Some working functionality can be developed quickly and early in the life cycle. ➢ Results are obtained early and periodically. ➢ Parallel development can be planned. ➢ Progress can be measured. ➢ Less costly to change the scope/requirements. ➢ Testing and debugging during smaller iteration is easy. ➢ Risks are identified and resolved during iteration; and each iteration is an easily managed milestone. ➢ Easier to manage risk - High risk part is done first. ➢ With every increment, operational product is delivered.
- 5. ➢ Issues, challenges and risks identified from each increment can be utilized/applied to the next increment. ➢ Risk analysis is better. ➢ It supports changing requirements. ➢ Initial Operating time is less. ➢ Better suited for large and mission-critical projects. ➢ During the life cycle, software is produced early which facilitates customer evaluation and feedback. DISADVANTAGES OF ITERATIVE: ➢ More resources may be required. ➢ Although cost of change is lesser, but it is not very suitable for changing requirements. ➢ More management attention is required. ➢ System architecture or design issues may arise because not all requirements are gathered in the beginning of the entire life cycle. ➢ Defining increments may require definition of the complete system. ➢ Not suitable for smaller projects. ➢ Management complexity is more. ➢ End of project may not be known which is a risk. ➢ Highly skilled resources are required for risk analysis. ➢ Projects progress is highly dependent upon the risk analysis phase.
- 6. SPIRAL MODEL: The spiral model is the combination of iterative model and classic life cycle model i.e waterfall model.A software project repeatedly passes through these phases in iterations is called Spirals. Some of the process based on the spiral model: ➢ Identification ➢ Design ➢ Construct and design ➢ Evaluation and risk analysis. APPLICATION FOR SPIRAL MODEL: ➢ When there is a budget constraint and risk evaluation is important. ➢ For medium to high-risk projects. ➢ Long-term project commitment because of potential changes to economic priorities as the requirements change with time. ➢ Customer is not sure of their requirements which is usually the case. ➢ Requirements are complex and need evaluation to get clarity. ➢ New product line which should be released in phases to get enough customer feedback. ➢ Significant changes are expected in the product during the development cycle. ADVANTAGES OF SPIRAL MODEL: ➢ Changing requirements can be accommodated. ➢ Allows extensive use of prototypes. ➢ Requirements can be captured more accurately. ➢ Users see the system early. ➢ Development can be divided into smaller parts and the risky parts can be developed earlier which helps in better risk management.
- 7. DISADVANTAGES OF SPIRAL MODEL: ➢ Management is more complex. ➢ End of the project may not be known early. ➢ Not suitable for small or low risk projects and could be expensive for small projects. ➢ Process is complex ➢ Spiral may go on indefinitely. ➢ Large number of intermediate stages requires excessive documentation. V-MODEL: The V-model is an SDLC model where execution of processes happens in a sequential manner in a V-shape. It is also known as Verification and Validation model. The v-model is the extension for waterfall model and is based on the association of testing phase for each corresponding development process. This means in development process every stages there is an associative testing process. There are several verification phases they are ➢ Business Requirement Analysis ➢ System Design ➢ Architectural Design ➢ Module Design. Some of the validation phases are ➢ Unit Testing ➢ Integration Testing ➢ System Testing ➢ Acceptance Testing APPLICATION FOR V-MODEL: ➢ Requirements are well defined, clearly documented and fixed. ➢ Product definition is stable.
- 8. ➢ Technology is not dynamic and is well understood by the project team. ➢ There are no ambiguous or undefined requirements. ➢ The project is short. ADVANTAGES OF V-MODEL: ➢ This is a highly-disciplined model and Phases are completed one at a time. ➢ Works well for smaller projects where requirements are very well understood. ➢ Simple and easy to understand and use. ➢ Easy to manage due to the rigidity of the model. Each phase has specific deliverables and a review process. DISADVANTAGES OF V-MODEL: ➢ High risk and uncertainty. ➢ Not a good model for complex and object-oriented projects. ➢ Poor model for long and ongoing projects. ➢ Not suitable for the projects where requirements are at a moderate to high risk of changing. ➢ Once an application is in the testing stage, it is difficult to go back and change a functionality. ➢ No working software is produced until late during the life cycle. BIG BANG MODEL: The Big Bang model is an SDLC model where we do not follow any specific process. The development just starts with the required money and efforts as the input, and the output is the software developed which may or may not be as per customer
- 9. requirement. This Big Bang Model does not follow and there is very little planning required. Even the customer is not sure about what exactly he wants and the requirements are implemented on the fly without much analysis. This model is ideal for small projects with one or two developers working together and is also useful for academic or practice projects. It is an ideal model for the product where requirements are not well understood and the final release date is not given. APPLICATION FOR BIGBANG MODEL: The Big Bang Model comprises of focusing all the possible resources in the software development and coding, with very little or no planning. The requirements are understood and implemented as they come. Any changes required may or may not need to revamp the complete software. This model is ideal for small projects with one or two developers working together and is also useful for academic or practice projects. It is an ideal model for the product where requirements are not well understood and the final release date is not given. ADVANTAGES OF BIG BANG MODEL: ➢ This is a very simple model. ➢ Little or no planning required. ➢ Easy to manage. ➢ Very few resources required. ➢ Gives flexibility to developers. ➢ It is a good learning aid for new comers or students. DISADVANTAGES OF BIG BANG MODEL: ➢ Very High risk and uncertainty. ➢ Not a good model for complex and object-oriented projects.
- 10. ➢ Poor model for long and ongoing projects. ➢ Can turn out to be expensive if requirements are misunderstood. AGILE MODEL: Agile SDLC model is a combination of iterative and incremental process models with focus on process adaptability and customer satisfaction by rapid delivery of working software product. Agile Methods break the product into small incremental builds. These builds are provided in iterations. Each iteration typically lasts from about one to three weeks. Agile model believes that every project needs to be handled differently and the existing methods need to be tailored to best suit the project requirements. In Agile, the tasks are divided to time boxes (small time frames) to deliver specific features for a release. Some of the various process involed in agile model are ✔ Planning ✔ Requirements Analysis ✔ Design ✔ Coding ✔ Unit Testing and ✔ Acceptance Testing. ADVANTAGES OF AGILE MODEL: ➢ Is a very realistic approach to software development. ➢ Promotes teamwork and cross training. ➢ Functionality can be developed rapidly and demonstrated. ➢ Resource requirements are minimum. ➢ Suitable for fixed or changing requirements ➢ Delivers early partial working solutions. ➢ Good model for environments that change steadily. ➢ Minimal rules, documentation easily employed. ➢ Enables concurrent development and delivery within an overall planned context. ➢ Little or no planning required. ➢ Easy to manage. ➢ Gives flexibility to developers.
- 11. DISADVANTAGES OF AGILE MODEL: ➢ Not suitable for handling complex dependencies. ➢ More risk of sustainability, maintainability and extensibility. ➢ An overall plan, an agile leader and agile PM practice is a must without which it will not work. ➢ Strict delivery management dictates the scope, functionality to be delivered, and adjustments to meet the deadlines. ➢ Depends heavily on customer interaction, so if customer is not clear, team can be driven in the wrong direction. ➢ There is a very high individual dependency, since there is minimum documentation generated. ➢ Transfer of technology to new team members may be quite challenging due to lack of documentation. RAPID APPLICATION DEVELOPMENT MODEL: RAD model is Rapid Application Development model. It is a type of incremental model. In RAD model the components or functions are developed in parallel as if they were mini projects. The developments are time boxed, delivered and then assembled into a working prototype. This can quickly give the customer
- 12. something to see and use and to provide feedback regarding the delivery and their requirements. Some of the phases of rapid application development model are: ✔ Business modeling. ✔ Data modeling. ✔ Process modeling. ✔ Application generation. ✔ Testing and turnover. APPLICATION FOR RAD MODEL: ➢ RAD should be used when there is a need to create a system that can be modularized in 2-3 months of time. ➢ It should be used if there’s high availability of designers for modeling and the budget is high enough to afford their cost along with the cost of automated code generating tools. ➢ RAD SDLC model should be chosen only if resources with high business knowledge are available and there is a need to produce the system in a short span of time (2-3 months). ADVANTAGES OF RAD MODEL: ➢ Reduced development time. ➢ Increases reusability of components ➢ Quick initial reviews occur ➢ Encourages customer feedback ➢ Integration from very beginning solves a lot of integration issues. DISADVANTAGES OF RAD MODEL: ➢ Depends on strong team and individual performances for identifying business requirements. ➢ Only system that can be modularized can be built using RAD ➢ Requires highly skilled developers/designers. ➢ High dependency on modeling skills ➢ Inapplicable to cheaper projects as cost of modeling and automated code generation is very high.