Rapid Application Development

Software development is as creative as making a painting. Thus the developer should have the freedom to add or revoke any feature at any point in time to make the product without having the fear that the end product might get ruined. Rapid Application Development is a model in software development where more importance is given to prototyping and feedback. Along with this, it is also ensured that they take place rapidly. It opposes the dragged cycles of development and testing.

RAD was originally developed because of the inefficiency of the original waterfall model. The waterfall model does not allow changes after the completion of a particular phase. Therefore if there are scenarios where the software requires to evolve it becomes difficult. 

Rapid Application Development promotes changes in the software and encourages evolution throughout the process. 

During its initial existence, rapid application development came about as a Spiral model. This basically meant using more development models at a particular time. 

Phases of Rapid Application Development Model

The different phases of the Rapid Application Model are:

Business Modeling

In this step, data is collected from different sources. After the data is collected, they are processed to be able to understand how they can be used for successful project execution. 

The type of information that is generated in this model are:

• The information required pre and post development for better quality work and a successful business. 
• Information stating the result and progress. This helps in determining if any changes are required in the process to make the project better.
• Information about how the collected information is being transferred from one point to the other. 
• Information about how to make changes if required in the collected information set. 

Data Modeling

All the data that had been collected during business modeling are utilized in this stage. The data is analyzed and categorized into different groups for easier understanding and utilization. Every data in the group is given a proper description. A relationship between these groups is established.

Process Modeling

In the process modeling phase, the information that had been collected in the earlier stages is transformed into data that can be used. Here if there are any changes that are required can be done. The data can be optimized and defined more in the process modeling phase. 

Application Generation

The information that had been collected in the process modeling step is now put into codes. A prototype of the system to be used is made. Data models already present are converted to prototypes to be tested later. 

Testing and Turnover

In the testing and turnover phase testing of the prototypes is done. The prototype is divided into separate models and tested individually with the aim of creating a very effective product. After this phase, there are usually no risks or errors left in the product.  

Rapid Application Development Methodology 

There are four main phases in Rapid Application Development Methodology. These phases are as follows:

Defining the requirements

The team involved in the project including the manager, the IT staff as well as the users all come together to define the pointers like the need of the project, the scope, the problems that might arise, and the aims and requirements. RAD makes sure that the limits of requirements are wide so that the project is flexible. 

User Input

In the second phase, prototypes are made according to the requirements of a team including developers and end-users. This phase is supposed to take place continuously and the user is supposed to use the product to provide feedback to the developer. 

Construction 

The user input and the construction phase work together. The feedback given by the user in the user input phase is put to use in the construction phase. It is usually done with coding and testing. The construction phase and user input phase continue till the point the user is satisfied with the results. 

Finalization

After the user input phase and the construction phase concludes and if the user is completely satisfied with the end product it is finalized. Things like testing and training are done to give the final touches to the product. The longevity and stability of the product are verified after which is delivered to the customer.

When to use RAD Methodology 

Rapid Application Development Methodology is used:

• If the production time of the product is less e.g. within a span of a few days.
• If the deliverables and requirements are already decided upon.
• If the customer or user has the opportunity to be able to be involved in all the stages of the life cycle.
• If the possibility of technical errors are lesser. 
• If the budget is on the higher end so that designers can be appointed. Higher budget is also required for usage of automated tools to be used to generate codes. 

Rapid Application Development Lifecycle 

The different stages of Rapid Application Development Lifecycle are:

• Planning: aim, scope and feasibility of a project is determined in this stage.
• Analysis: the aims and goals of the project are studied to understand the needs. 
• Design: different intricate details such as features, the layout of the page and rules of the program are considered to make the aim of the project more definite. 
• Implementation: development of the project is done. Development continues till it’s ready for the customer. 
• Testing: as the name suggests, testing is done for an accurate product. 
• Evaluation: this stage refers to the stage where evaluation of the product is done at regular intervals to keep the product updated.

Advantages of Rapid Application Development

The advantages of Rapid Application Development are:

• As the name suggests the delivery time is fast in RAD because of its iterative approach. 
• When any development process takes place there are changes along the way. RAD supports and encourages changes in the process. 
• The number of errors in this process are comparatively lower than other processes which makes the process of testing easier and less time consuming.
• The cost of development is lower than other processes. 
• The cost of maintenance is lower than other processes.
• If RAD is specially used for application development then if a new version has to be released, then the time taken is really less because it involves adding an iteration.
• If a new technology has to be added it can be done easily with RAD.
• There is a lot of involvement with the end user making the process of development more efficient. 

Disadvantages of Rapid Application Development 

Every coin has two sides. Similarly, Rapid Application along with having its set of advantages has its own forms of disadvantages. 

The disadvantages of Rapid Application Development are:

• RAD is very efficient when results are required soon. But the nature of RAD also changes the requirements at regular intervals which inturn changes the design thus changing the course of bigger projects. 
• Another important part of RAD is to collect feedback from the users. Therefore if for some reason, the user is absent then the process breaks and consistency is lost. This thus affects the quality of work too. 

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