Designing software is not an easy process. It requires a lot of planning and technical knowledge. How do software developers design new software? The answer is the software development lifecycle. This is a basic structure that helps software developers to design their software properly. It ensures that they design the software in a timely manner. It also helps in creating the software with minimum wastage of resources and at a low cost. There are different software development lifecycle models that a developer can follow. These models guide developers in the entire process. Let us understand more about the models.
Software Development Lifecycle Models
A software developer has to design different kinds of software. They get a variety of projects. Simple projects require a short amount of time. Alternatively, some projects may be complex. They may require a long-term process of designing. Additionally, the developer also has to ensure regular revision and modification of software. For this, having a structured approach is very necessary. This is where software development lifecycle models are useful.
Software development lifecycle models are a guide for developers. These models depict the different stages of software development. A developer can design software by implementing one of the models. Different projects have different requirements. Developers cannot create all software using a single method. This is where the different models play their role. Some models are useful for short-term projects while some are useful for long-term projects. Further, some models can be helpful for a simple software design whereas, for complex designs, another model may be helpful. On the basis of requirements, we have different models.
Let us check out the different software development lifecycle models. The first and the basic model is the waterfall model. Next, we have the spiral model. A V-shaped model is an advanced version of the waterfall model. The prototype model is a unique model. It is useful for projects having specific requirements. The agile model is an important software development lifecycle model. Finally, we have the iterative model and the iterative enhancement model. There are some common elements in each model. Developers can pick the model which suits their project the best. Let us now check out all the models in detail.
Let us begin with the simplest of all the software development lifecycle models. The waterfall model is the first model for software development. It is the most basic method of the software development lifecycle. Why do we call it the waterfall model? Let us try to understand. Imagine how a waterfall looks. The water flows from the top of the mountain to the bottom. Thus, there is a direct flow from top to bottom. The water has to pass all the areas before it reaches the bottom. This is exactly how a waterfall model works.
The waterfall model adopts a top to bottom approach. It is very simple. The steps are linear. This means that one can move to the next stage only after completing the previous one. Thus, the process follows a sequence. For this reason, we also call it the Linear-Sequential Lifecycle Model. This model is useful for simple and short-term projects. It is not very useful for complex projects that require long-term planning and implementation. The waterfall model was the first and most basic of all the software development lifecycle models.
The first stage in this model is the requirement analysis. Developers list down all the requirements for software development. Thereafter, they analyze the requirements. The next stage is the system design. In this stage, the main designing process happens. The developers present a system design for the software that they are developing. In the implementation stage, developers code the software. Thereafter, the developers test the system to see if it works properly. When the software is ready, they deploy it to the customers. This concludes the software development process. Afterward, they do regular maintenance to manage and update the software.
The spiral model is a combination of two software development lifecycle models. It is a combination of the waterfall model and iterative model. Thus, it has the benefits of both models. It is a very important model. It is good for complex projects as it allows more flexibility. As the name suggests, this model follows the steps in a spiral design. Let us understand the stages of this model. The spiral model of software development lifecycle has four stages.
The first stage is evaluation and planning. In this stage, developers plan for the project. They properly evaluate the project to create a suitable plan. The next stage is the objective determination stage. In this, they list down the main goals and objectives. The third stage is an important stage of the spiral model. It is the risk analysis stage. A spiral model is generally helpful for complex projects in which there are more risks. Therefore, a proper analysis of all the possible risks is necessary. After the risk analysis, we move on to the final stage.
The final stage in the spiral model is the engineering stage. In this stage, the software designing process takes place. Hence, developers perform the coding, testing, and implementation in this stage. They send the project after its approval. In the case of maintenance, the entire spiral model has to be followed. This means that for modification or maintenance of the system, all the four stages have to be implemented again. This is why it is a spiral model.
The prototype model is unique from all the other software development lifecycle models. In this model, a prototype is first built. What do we mean by a prototype? A prototype is a sample design of the product. It shows how the final product will appear and how it will function. If the customer approves the prototype, then they design the actual product. The prototype model of the software development lifecycle follows the same concept.
The first step in this model is to gather the requirements of the customer. Developers create a prototype on the basis of the customer’s description. Thereafter, they show it to the customer to evaluate. The customer will ask for modifications or refinements. Thus, they make changes and build another prototype. This process continues until the customer approves the prototype. Once the customer approves the prototype, the developers work on the final product.
Developers will create a plan for the project based on the final prototype. Thereafter, they will start with the system design. In this stage, they perform the coding and create the software. Thereafter, they run the software. Thus, the software is implemented. After this, they test the software for any glitches. Once they do the testing, they present it to the customer for approval. The maintenance process is a continuous process to modify or to create a better version of the product. Thus, this is how the prototype model works.
In the list of software development lifecycle models, the next model is the iterative model. The iterative model repeats the process of software development. Hence, the name “iterative”. Let us elaborate on this. In the iterative model, it is possible to design the product on preliminary requirements. This means that the developers focus on the current requirements. Firstly, they analyze the current requirements. Thereafter, the system design process takes place. This includes coding. Once the system design is ready, they perform the testing. Finally, they implement the product.
Now, if additional requirements come up, developers repeat the whole process. They will first analyze the new requirements. Thereafter, they will generate system design. Coding and testing take place. Finally, they implement the product. Whenever new requirements are brought up, they perform the whole process. Thus, they follow a fresh lifecycle process for every modification.
Due to this feature of the iterative model, it is suitable for long-term projects. Repeating the entire model for every new requirement is costly and time-consuming. Therefore, it is not suitable for short-term projects. Hence, developers generally use the iterative model is for long-term projects.
The V-shaped model is a newer and more complex version of the waterfall model. In fact, we can call it an extension of the waterfall model. As the name suggests, the steps of this model can be denoted by the alphabet V. This means that the developers can move on to the next step only if the previous step is complete. Therefore, this model follows the step-by-step process for software development.
Let us look at the stages of the V-shaped model. The first stage is the planning stage. After planning, developers perform the analysis of requirements. They write down the requirements and then note the specifications. Thus, the developers are very careful about the details. It is useful for projects that require a rigid and specific product. After noting the specifications, developers work on high-level designs. These are the basic modules of the software. They form the base for the system. The next step is to develop low-level designs. These are descriptions of the high-level designs. Finally, they work on coding.
Developers divide the testing into different phases. Firstly, they test the individual units of the system. Thereafter, they integrate all the individual units and test them together. Finally, they test the whole system. The final product is then presented to the customers. Once it passes the acceptance testing done by the customers, the process is complete. The product can now be delivered to the customer. The V-shaped model is ideal for short-term projects with specific needs. This model is also known as the Validation and Verification method as each step is tested before moving on to the next step.
The agile model is a very efficient model of the software development lifecycle. It takes into account the rapid changes in technology. Therefore, it develops products that are up-to-date with market trends. In the agile model, the product is divided into different parts. Different features of the product are designed separately. Generally, each feature is given a time of 2-3 months. Once one feature is designed, it is presented to the customer for approval. In this manner, the product is divided into parts. In the end, the whole product is presented.
The requirements for the first part of the product are analyzed. Thereafter, planning and designing are done. After coding, testing is done. Once it is tested and implemented, it is presented to the customer. This process is completed in 2-3 months. Thereafter, the developers move on to the next part of the product. The same process is repeated. Once the second part is implemented, the developers present the first and second parts to the customer together. In this manner, they develop the entire product in parts. This enables the developers to employ the latest methods and technology into designing the product.
Iterative Enhancement Model
The final model in the list of software development lifecycle models is the iterative enhancement model. We also call it the incremental model. This model can overcome the limitations of the waterfall model. It is similar to the waterfall model. However, the steps are in increments. Let us see how this model works.
The first step is the analysis of the requirements. This is the same in all the models. The next step is the designing stage. The developers go back to the requirements stage after creating the system design. They do this to ensure that nothing is missed out from the previous stage. After this, they move on to coding. Again, the developers check the previous stages to see if all the features are included. Thereafter, they do the testing and implementation. During these steps too, they check the previous stages. Thus, the developers keep going back to check whether all the previous steps are followed.
Software developers use these software development lifecycle models for developing different software projects. These models help in developing software according to different requirements and needs of the customer.