There are several various types of life cycle models to build a system in Software Development. Each system process follows a particular life cycle model in order to complete the system successfully. Such as Waterfall model, V model, Prototype Model, Spiral Model, Dynamic System Development Methodology, Rapid application Methodology and Joint Application Development.
Water Fall Model
Water fall is one of the process models which is first introduced and widely used in software development. The whole process of a system is divided into separate processing stages. When we consider about the waterfalls once the water has flowed from the mountain and it starts its journey it cannot turn back. Like that each stage starts after the previous stage is finished.
The stages in Waterfall model are: Problem Definition, Requirement Analysis, System Design, Coding & Testing, Implementation and Maintenance.
Advantages of Waterfall Model
Can easily understand the stages and the activities.
Measurable progress of the system.
When undergoing project it helps to plan and schedule.
Stable Project requirements.
Strict sign-off requirements.
Disadvantages of Waterfall Model
Difficult to go backward.
Suitable only for small project.
Difficulty responding to changes.
V model is also a software development process, which overcomes some of the drawbacks of the waterfall model. It moves down in linear shape and it bends upward after the Database software design (coding) stage. It was named V Model because it forms the “V” shape. It is a well structured method. Each stage starts after the completion of the previous stage like Waterfall Model. V Model shows the relationship between the problems which is found at the early stages and in the later stages. The V Model mostly focuses on verification and the validation and it shows how the activities are built in to it.
Advantages of V Model
Simple and easy to use.
Errors will be corrected in each phases.
V Model emphasis the strict process flow to develop a quality product.
Verification and validation will be tested while processing is going on.
Disadvantages of V Model
It needs lots of resources.
It can be implemented by only some big companies
The user involves after the system is developed.
This prototype is better than the Waterfall and the V Models. It is easy to manipulate. It starts with the stage gathering requirements. This model helps to increase the flexibility of the development process by allowing the client to involve and to share their opinion about how the proposed system might look and feel. The process will continue only after the client’s satisfaction. This model could be speared to others since there are no stages of process. Everyone has to work at the same time. It reduces the man hours in building a system. The process will be faster and efficient. There are three types of prototyping.
Throw away Prototyping.
Incremental development prototyping.
Advantages of Prototype Model
Reduces processing time.
Reduces development cost.
Clients can involve.
Developers can receive client’s feedback.
Higher clients’ satisfaction.
Customer doesn’t have to wait as in the previous models.
Errors can be detected.
Disadvantages of Prototype Model
It can lead to insufficient analysis.
Developers can become too attached to their prototype.
Sometimes it leads to incomplete documentation.
It is not suitable for large Application.
Sometimes it leads the system to be unfinished.
Possibility of implementing systems before they are ready.
Spiral Lifecycle Model
The spiral model was introduced by Barry Boehm in 1988. This model combines the features of the waterfall and the prototype model. Spiral model is suitable for large, complicated projects. It is expensive. This model was not the first model to discuss iterative development, but it was the first model to explain why the iteration matters.
Each phase starts with a design goal and ends with the client (who may be internal) reviewing the progress thus far. Analysis and engineering efforts are applied at each phase of the project, with an eye toward the end goal of the project. There are five stages in this model. Such as Define, Design, Demonstrate, Develop & Deliver.
Advantages of Spiral Model
Suitable for large and complex projects.
Avoidance of Risk is enhanced.
Strong approval and documentation control.
Implementation has priority over functionality.
Additional Functionality can be added at a later date.
Disadvantages of Spiral Model
Development cost is high.
When the risk is not discovered problems will occur.
Not suitable for small projects.
5. Dynamic System Development Method (DSDM)
Dynamic System Development Method is another approach to system development, which, as the name suggests, develops the system dynamically. This methodology is independent of tools, in that it can be used with both structured analysis and design approach or object-oriented approach.
The Dynamic System Development Method (DSDM) is dynamic as it is a Rapid Application Development method that uses incremental prototyping. This method is particularly useful for the systems to be developed in short time span and where the requirements cannot be frozen at the start of the application building. Whatever requirements are known at a time, design for them is prepared and design is developed and incorporated into system. In Dynamic System Development Method (DSDM), analysis, design and development phase can overlap. Like at one time some people will be working on some new requirements while some will be developing something for the system. In Dynamic System Development Method (DSDM), requirements evolve with time.
Dynamic System Development Method (DSDM) has a five-phase life cycle as given the following figure
Dynamic System Development Method
Rapid Application Development Model
RAD is a linear sequential software development process model that emphasis an extremely short development cycle using a component based construction approach. If the requirements are well understood and defines, and the project scope is constraint, the RAD process enables a development team to create a fully functional system with in very short time period.
Advantages of RAD
There are many advantages of using RAD and it can solve many concerns of the user as well as the developers.
Conventional software development methods take, on an average almost 20% more time than the RAD procedure. Using RAD can enable quicker visualization of the end-design and hence allow rapid software testing and rectifying steps. The customer is able to have a faster look at the design to add valuable inputs, in order to make the design more user-friendly.
The current competitive scenario demands frequently upgraded softwares in order to effectively satisfy customers’ requirements. RAD enables a faster and updated version to reach the end user, by systematically eliminating redundant steps or using the prototype methods.
Cost overruns and meeting the time constraints are another advantage, though not a big consideration in high-end uses.
RAD makes the development process to be a more credible one by facilitating a scope for the customer to actively provide inputs in the development process. This may also prove a feasible study from the point of view of a developer.
It protects the current project from the variations in the market.
Disadvantages of RAD
Requires a system that can be modularized
Requires highly skilled and well-trained developers.
Joint Application Development
Joint Application Development (JAD) is a development methodology system originally used for designing a computer-based system, but can be applied to any development process. It involves continuous interaction with the users and different designers of the system in development. JAD centers on a workshop session that is structured and focused. Participants of these sessions would typically include a facilitator, end users, developers, observers, mediators and experts. JAD allows for a faster development process and minimizes errors at the same time. JAD also improves the quality of the final product by focusing on the up-front portion of the development lifecycle, thus reducing the likelihood of errors that are expensive to correct later on.
Disadvantages of Join Application Development
More people in JAD teams meets less time available for all of them to speak.
Some people are afraid to speak for fear that they will be criticized.
In these models I would like to select Waterfall Model.
It is very simple.
We can easily understand the stages and the activities clearly.
Useful for small projects like this hospital system.
Need very few resources.
The amount for the resources is very low.
When we consider about the other models there are some drawbacks.
In V model it needs lots of resources. It is too expensive. So this is not suitable for this system.
Prototype model can lead to insufficient analysis and incomplete documentation. So this is also not suitable.
Spiral model needs considerable risk assessment and if any risk is not discovered Problem will surely occur .So this is very risky.
Rapid Application Development model is less efficient. And the other life cycle model also having some serious drawbacks.
Although the Water Fall Model is having some drawbacks it is more suitable for the Hospital system. Because of that I have chosen the Waterfall Model to develop this system.
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