A Comparative Study of Universally Accepted SDLC Models for Software Development

© 2018 IJSRST | Volume 4 | Issue 5 | Print ISSN: 2395-6011 | Online ISSN: 2395-602X Themed Section: Science and Technology A Comparative Study of Universally Accepted SDLC Models for Software Development Madhup Kumar M.Tech Research Scholar, Jharkhand Rai University, Ranchi, Jharkhand, India ABSTRACT A software life cycle is the series of identifiable stages that a software product undergoes during its life time. An s/w life cycle model is a descriptive and diagrammatic representation of s/w life cycle. A life cycle model map the different activities performed on a s/w product from its inspection to retirement. Business organization follow steps-Business process, manufacturing industries-manufacturing process same as for s/w development use s/w process model. The first life cycle of any s/w product is generally feasibility study, RAS, Design, Coding, Testing and Maintenance. A (software/system) life cycle model is a description of the sequence of activities carried out in an SE project, and the relative order of these activities. Keywords: Software Engineering, SDLC, Comparative Life Cycle Model I. INTRODUCTION model. SDLC model has some phase like FS, RS, Designing, Coding, Testing, Maintenance etc. Advent of computers has voraciously changed our lives. Earlier its usage was limited for personal use or Objective of this research paper is to find out for particular task but now computer is used widely. A to use which model. advantages, drawbacks of each SDLC model and when software engineering discipline gives us method, process, tools etc for developing computer software.[1] The remainder of this paper is organized as follows: Software engineering is tool for software developers Sect. II discusses the study of several SDLC models for developing error free software in systematic and in with their usage, advantages and disadvantages. discipline manner as per user requirements. Delivery Section III compares each of the methods with of the software should be in time and in budget. In reference to their contemporary models. Section IV past year traditional approach were used for concludes the paper and discusses future scope. developing software .But that method is not fit for these days it had several limitation [2].Now these days II. STUDY OF SEVERAL SDLC MODELS there are several process model by which we can develop our software that is called SDLC (software development life cycle model) each model has some phases and a software undergoes each phase of SDLC model[3]. Software developers are free to adopt any life cycle model it’s depend on developer team and nature of the developing software[4]. Every SDLC 2.1 Classical Waterfall Model Feasibility Study RA&S Design Coding model has some advantages and some limitations also[5]. In this paper we compare each SDLC model its Testing advantages, limitation and when to use which SDLC IJSRST1845202 | Received : 20 March 2018 | Accepted : 31 March 2018 | March-April-2018 [ (4) 5 : 1084-1092] Maintenance 1084 Madhup Kumar et al. Int J S Res Sci. Tech. 2018 Mar-Apr;4(5) : 1084-1092 Figure 1. Steps involved in the Classical waterfall Model. 2.1.1 When to use the waterfall model: [9, 10]  When the requirements are Figure 2. Steps involved in the Iterative waterfall Model 2.2.1 When to use the Iterative model: very well understood and fixed. All the phases of this model are same as classical waterfall model. Condition for using this model is also  When Product definition is constant.  When Technology is understood. same as classical waterfall model.  When 2.2.2 Advantages of Iterative waterfall model:  When there are no confusing requirements. sufficient resources with required expertise are available without restraint.  When the project is short Advantages of Iterative waterfall model is same as classical waterfall model including one or more feature added in this model i.e. Iteration is possible In this model developer can go back form one phase to 2.1.2 Advantages of waterfall model:  User friendly, easy to use and understand  It is easy to manage due to the inflexibility of the model  Phases do not go beyond.  These models manly used for smaller projects where requirements are very well understand. 2.1.3 Disadvantages of waterfall model:  Iteration problem (it is very difficult to go back from one phase to another phase.)  Late delivery of the software.  High amounts of risk and ambiguity.  Not feasible for complex and object-oriented projects.  Not fit for long and ongoing projects.  Not good where high risk chances occur and the requirements are moderate. 2.2 Waterfall Iterative Model [7] another i.e. if some problem occur in one phase iteration is possible (go back to one phase to another phase). Iterative waterfall model overcome the one of the iteration problem of waterfall model. This model is same as classical waterfall model all process of developing project are same as waterfall model. 2.2.3 Disadvantages of Iterative Model of SDLC  Iterations possible but may cause confusion as the project proceeds.  In this model we freeze software and hardware. But not advisable especially in long-term projects.  Requirement gathering is a tough task.  Change in any previous stage can cause big problem (Dependency).  Iteration can be a costly. 2.3 Prototype Model [5] . Figure 3. Steps involved in design of Prototype Model International Journal of Scientific Research in Science and Technology (www.ijsrst.com) 1085 Madhup Kumar et al. Int J S Res Sci. Tech. 2018 Mar-Apr;4(5) : 1084-1092 2.3.1 When to use the prototype model:  When the end users have lot of interaction with system.  For developing online systems, web interfaces, like system are appropriate for this model. A little bit user training is required for this system.  Feedback is necessary from user/customer for development of this model the user can use the system before final delivery of the system. 2.3.2 Advantages of Prototype model:  User’s involvement in the development cycle.  Since in this methodology a working model of the system is provided, the users get a better Figure 4. Design flow of the Incremental Model understanding of the system being developed.  Errors can be detected much earlier.  Quicker user feedback is available leading to better solutions.  Missing functionality can be identified easily  Confusing identified or difficult Requirements functions validation, can 2.4.1 When to use the Incremental model: [8]  This model can be used when the requirements of the complete system are clearly defined and be Quick implementation of incomplete, but functional applications. understood.  Major requirements must be defined; however, some details can evolve with time.  When there is an immediate need to get a product to the market early. 2.3.3 Disadvantages of Prototype SDLC model:  Leads to implementing and then repairing way of building systems.  Practically, this methodology may increase the complexity of the system as scope of the system may expand beyond original plans.  Incomplete application may cause application not to be used as the full system was designed Incomplete or inadequate problem analysis. 2.4 Incremental Model  A new technology is being used  Resources with needed skill set are not available  There are some high risk features and goals. 2.4.2 Advantages of Incremental model:[11]  Generates working software quickly and early during the software life cycle.  This model is more flexible – less costly to change scope and requirements.  It is easier to test and debug during a smaller iteration.  In this model customer can respond to each built.  Lowers initial delivery cost.  Easier to manage risk because risky pieces are identified and handled during its iteration. International Journal of Scientific Research in Science and Technology (www.ijsrst.com) 1086 Madhup Kumar et al. Int J S Res Sci. Tech. 2018 Mar-Apr;4(5) : 1084-1092 2.4.3 Disadvantages of Incremental model:  Needs good planning and design.  Needs a clear and complete definition of the whole system before it can be broken down and built incrementally.  Total cost is higher than the waterfall model. 2.5 Spiral Model 2.5.3 Disadvantages of Spiral model:  Can be a costly model to use.  Risk analysis requires highly specific expertise.  Project’s success is highly dependent on the risk analysis phase.  Doesn’t work well for smaller projects. 2.6 The V-model Figure 5. The phases involved in the Spiral Model 2.5.1 When to use Spiral model: Figure 6. The step-by step phases involved in V model  For medium to high-risk projects 2.6.1 When to use the V-model: [10]  When costs and risk evaluation is important  Long-term project commitment unwise because of potential changes to economic priorities  Users are unsure of their needs  Requirements are complex  New product line  Significant changes are expected (research and exploration)  The V-shaped model should be used for small to medium sized projects where requirements are clearly defined and fixed.  The V-Shaped model should be chosen when ample technical resources are available with needed technical expertise.  High confidence of customer is required for choosing the V-Shaped model approach. Since, no prototypes are produced, there is a very high 2.5.2 Advantages of Spiral model [5]  High amount of risk analysis hence, avoidance of Risk is enhanced.  Good for large and mission-critical projects.  Strong approval and documentation control.  Additional Functionality can be added later.  Software is produced early in the software life cycle. risk involved in meeting customer expectations. 2.6.2 Advantages of V-model:  Simple and easy to use.  Testing activities like planning, test designing happens well before coding. This saves a lot of time. Hence higher chance of success over the waterfall model prevails. International Journal of Scientific Research in Science and Technology (www.ijsrst.com) 1087 Madhup Kumar et al. Int J S Res Sci. Tech. 2018 Mar-Apr;4(5) : 1084-1092  Proactive defect tracking – that is defects are found at early stage.  Avoids the downward flow of the defects.  Works well for small projects where requirements are easily understood. 2.6.3 Disadvantages of V-model:  Very rigid and least flexible.  Software is developed during the implementation phase, so no early prototypes of the software are produced.  If any changes happen in midway, then the test documents along with requirement documents has to be updated. 2.7 RAD model 2.7.1 When to use RAD model:[11]  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 Figure 7. The parallel phases of the RAD Model 2.7.2 Advantages of the 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 issue. 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). 2.7.3 Disadvantages of RAD model:  Depends on strong performances requirements. for team and individual identifying business  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. 2.8 Agile model 2.8.1 When to use Agile model:[11] Agile technology is used when new changes are needed to be implemented. The freedom agile gives to change is very important. International Journal of Scientific Research in Science and Technology (www.ijsrst.com) New changes can 1088 be Madhup Kumar et al. Int J S Res Sci. Tech. 2018 Mar-Apr;4(5) : 1084-1092 implemented at very little cost because of the frequency of new increments that are produced.  People and interactions are emphasized rather than process and tools. Customers, developers and testers constantly interact with each other.  Working (weeks software is delivered frequently rather than months).  Face-to-face conversation is the best form of communication.  Close,daily cooperation between business people and developers. Figure 8 .The phases of the Agile Model  Continuous attention to technical excellence and good design. To implement a new feature, the developers need to lose only the work of a few days, or even only hours, to roll back and implement it.  Regular adaptation to changing circumstances.  Even  Unlike the waterfall model, in agile model very 2.8.3 late changes in requirements are welcomed Disadvantages of Agile model:[6] limited planning is required to get started with the project. Agile assumes that the end users’ needs are  In case of some software deliverables, especially the large ones, it is difficult to assess the effort ever changing in a dynamic business and IT world. required at the beginning of the software Changes can be discussed and features can be newly development life cycle. affected or removed based on feedback. This effectively gives the customer the finished system they want or need.  There is lack of emphasis on necessary designing and documentation.  The project can easily get taken off track if the customer representative is not clear what final Both system developers and stakeholders alike, find outcome that they want. options  Only senior programmers are capable of taking than if the software was developed in a more rigid the kind of decisions required during the sequential way. Having options gives them the development process. Hence it has no place for decisions until more or newbie programmers, unless combined with they also get more freedom of time and ability to leave important better data or even entire hosting programs are experienced resources. available; meaning the project can continue to move forward without fear of reaching a sudden standstill. 2.8.2 Advantages of Agile model:  Customer satisfaction by rapid, continuous delivery of useful software. III. COMPARATIVE STUDY OF SEVERAL SDLC MODELS 3.1 AGILE vs. SPIRAL TABLE 1. COMPARISON OF AGILE AND SPIRAL MODEL AGILE MODEL Sustainability and maintenance is risky. SPIRAL MODEL Improved risk management. International Journal of Scientific Research in Science and Technology (www.ijsrst.com) 1089 Madhup Kumar et al. Int J S Res Sci. Tech. 2018 Mar-Apr;4(5) : 1084-1092 Documents and rules are easily employ. No planning required. Large number of transitional stages requires extreme documentation. Required. Easy to use. More complex. Partial working model delivered. At end of the phases. Good for small type software. Not good for small and low risk software. Depends customer relations. Does not depend. All iteration is a split model. Not a split model Mixture of iterative and incremental model. Mixture of iterative and waterfall. 3.2 AGILE vs. ITERATIVE MODEL TABLE 2. COMPARISON OF AGILE AND ITERATIVE AGILE MODEL ITERATIVE MODEL It contains more risk of sustainability, maintainability and extensibility. Risks are identified and resolved during iteration. Agile method breaks the product in small incremental builds. These builds are provided in iteration. An iterative life cycle model, project is divided into different builds which are proceed iteratively. It is incremental and iterative model. So it can be used to build more complex project. It is iterative, all builds are developed, tested Iteratively. The main focus is on adaptability and customer satisfaction with rapid development of project. The main focus is on producing new version of software at the end of each iteration to satisfy customer needs. It can be used to develop more complex projects. It cannot be used for more complex projects as iterative practice will increase complexity, time requirement. Quick in development of application Various modules of the application can be developed simultaneously. Constant monitoring is required. More flexible with customer requirements. Comparatively slower development. Only 1 module is developed at a time. Monitoring is required after every iteration. Less flexible. Evaluation is done more frequently resulting in better error detection. Evaluation is after every iteration hence errors if any are detected after a delay. Progress cannot be clearly measured. Progress can be clearly measured. Least resources are required. More resources required. Agile development considers number of different iterative development. It includes all aspects of the methodologies with specific steps to produce a iterative lifecycle - requirements and then a release of software project example being Extreme Programming. the prototype. The Spiral Model on the other hand is an example of International Journal of Scientific Research in Science and Technology (www.ijsrst.com) 1090 Madhup Kumar et al. Int J S Res Sci. Tech. 2018 Mar-Apr;4(5) : 1084-1092 In an Incremental model, we build the overall solution in parts but at the end of each phase, feedback may not be provided. The model waits until the final stage for the incremental process to deliver the final product. In the Agile Development Model, customers, developers and testers constantly interact with each other. Developers encounter a freezing requirement where they are not allowed to modify the requirements or specification of the previous phase until the next iteration. Developers can refine or add requirements and specification to the system after the prototype is built. The complexity of an error increases because of the nature of the model; each phase is sequential of the other. The complexity of an error is low because the prototype enables the developer to detect any deficiency early at the process. 3.3 SPIRAL vs. WATERFALL IV. CONCLUSION TABLE 3. COMPARISON OF SPIRAL AND WATERFALL MODEL WATERFALL MODEL After a comprehensive review, it can be concluded Not fit for small projects. Fit for small projects. and advantages. All SDLC models are conditional as to Risk management is better. Risk and uncertainty is high. Process is complex. The process may become hazy . Good model for big and ongoing software. It follow Iterations process . Easily to understand. All Stages are well defined. Not good model for big and ongoing software. Sequence procces is followed. Requirements are fixed . SPIRAL MODEL that each of these models developed has its limitations when to implement which SDLC model it totally User requirements can be changed. Easy to Refinements . Repetition of Phases are possible. depends on nature of the Software. My future work is to minimize the drawback of SDLC models and to propose a new concise model with some new phase and eliminate the drawbacks of spiral and Iterative waterfall model. The effort would also be to implement a new method form SDLC phase in analogy with the requirement gathering phase to estimate size of the software as per the remarks observed in this research work. Not so easy. Not possible. V. REFERENCES WATERFALL vs. PROTOTYPE [1]. Ian Sommerville, Addison 3.4 WATERFALL vs. PROTOTYPE MODEL TABLE 4. COMPARISON OF WATERFALL AND PROTOTYPE Waterfall Model Client can only preview the system only after the final version of the software is developed because there is no feedback loop. Engineering", Wesley, ISBN-13: 978-0137035151, 9th edition, 2010. [2]. Rajib Mall, "Software Engineering principle" PHI, 4th edition, ISBN- 978-81-203-4898-1, Prototype Model Clients have a preview of the system from the "quick design" and the prototype developed early at the end of the process. 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