System Development Life Cycle (SDLC) model is the process of designing information systems, building them and delivering them to end-users in Information Technology (IT) businesses. In the development of information systems, SDLC models are highly recommended, because they assist in ensuring efficiency in development efforts and accomplishment of project goals. SDLC models vary in characteristics and number of stages. The seven-step and four-step SDLC models get described comprehensively as well as its features compared as applied in systems development.
Seven-step SDLC model
The seven-step SDLC model comprises of seven phases in the development of information systems. The steps are; project definition, user requirements definition, system requirements definition, analysis and design, system build, implementation and training and sustainment (Babers, 2015).
Phase 1: Project Definition
The IT project takes shape in this stage that comprises of planning as well as undertaking a feasibility study. The planning involves describing the desired features and operations of the proposed system. Some of the details outlined during planning include process diagrams, screen layouts and also other documentation. When the application proposal of the project is submitted for consideration, the proposed system is assessed using three aspects namely economic feasibility, technical feasibility, and operational feasibility. Technical feasibility focuses on whether the implementation of a proposed system would be successful in the organization. Economic feasibility compares the potential benefits with the anticipated cost of the proposed system. The operational feasibility evaluates how well the new system would operate given the status of systems and people in the organization. A project plan is then develop establishing the critical success factors, project scope and project milestones and responsibilities.
Phase 2: User Requirements Definition
This phase formally determines the needs that the proposed system must meet. This phase serves as the framework for system design and development. The system analyst puts the project objectives into defined functions and operation of the intended application in this phase. The system analyst works together with the end-users in this phase so as to understand the business processes fully and document the requirements of the proposed system.
Phase 3: System Requirements Definition
In this stage, the development team of the project establishes the technical/design specifications of the proposed application. Design specifications involve two main components namely technical architecture specification and systems model. The technical architecture specification outlines the hardware and software components as well as networking technology that the new information system will run. The systems model describes the interaction of systems processes and components using graphical models and also defines the interface between the user and the system by creating menu and screen formats for the whole system.
Phase 4: Analysis and Design
In this stage, the proposed system is put into production by IT programmers, database developers and network engineers who use the system design specifications to create the program and data files. The phase also involves the purchase of the hardware and IT infrastructure that was identified in the systems requirement definition phase.
Phase 5: System Build/Pilot
In this phase, the new system developed in the analysis and design stage is tested to ensure workability. The pilot test is also crucial since it assists in checking for bugs, errors, and interoperability. The testing in this phase takes place in multiple levels namely individual processing unit, system testing, inter-system testing and user acceptance testing (Li, 1990).
Phase 6: Implementation and Training
The real code gets written in the implementation and training step. The new system is ready for the actual working environment after the pilot test. The end-users of the new system are trained in this phase. The installation of system components and the transfer of old data to the new system also take place in this phase.
Phase 7: Sustainment
The last step is the maintenance of the new system in which modifications, corrections, and additions are made in the actual working environment to ensure that new system functions properly. A user support group and help desk should be established to assist in maintaining high performance, monitoring and identifying problems and supporting end-users.
Four-step SDLC model
The four-step SDLC model comprises of four stages namely systems requirements phase, analysis phase, design phase and implementation phase (Meersman & Tari, 2005).
Phase 1: Systems Requirements
This step entails determining why a new information system is required, the solution the new system provides to the business needs as well as determining how the project team will go about the development of the proposed system. The phase comprises of two main processes namely project initiation and project management. Project initiation involves the identification of the proposed system’s business value to the organization as well as conducting a feasibility study. The information systems approval committee then reviews the system request and feasibility analysis of which they approve or decline the development of a new system. In the project management process, the project manager develops a work plan, staffs the project and puts strategies in place that assist the development team through the SDLC process.
Phase 2: Analysis
The analysis phase entails determining the end-users of the new system, the functions of the new system, the actual working environment of the new system and when the new system will be operational. It consists of three processes namely analysis strategy, requirements gathering, and system proposal. The analysis strategy involves an assessment of the current system and its problems as well as approaches to design the new system. The requirements gathering process collect information of the needs of the proposed system through methods such as interviews or questionnaires. The system proposal process combines the analyses, system, concept, and models that then get presented to the project sponsor and other decision-makers.
Phase 3: Design
The design stage determines various components that are required for the development of the new system. The components include hardware, software and network infrastructure, the user interface, forms, and reports, as well as the specific programs. The design phase then proceeds through four processes. First, the design strategy is developed specifying who will develop the new system. Second, the architecture design is developed specifying the hardware and software components, as well as the network infrastructure. Third, database and file specification are drawn up specifying the data to be stored in the database. Lastly, the program design is developed by the analyst team that defines the programs to be written.
Phase 4: Implementation
The implementation phase entails the building of the actual system or purchase of an already built system such as in the case of a package software design (Dennis, Wixom & Tegarden, 2015). The implementation phase follows three main steps. The first step is the system construction in which the proposed system is built and tested. The second step is the installation of the new system in the actual working environment. Lastly, is the system plan established by the analyst team and identifies the major and minor changes required for the new system.
Comparison between a seven-step SDLC model and a four-step SDLC model
Different SDLC models have unique characteristics that present both advantageous and detrimental characteristics to a project depending on its type of requirements and features. The seven-step and four-step SDLC models have various similarities and differences when used in the development of information systems. The main similarity of all SDLC models and is also strength in the development of IT projects is that it makes the design process sequential and highly structured (Gupta, Forgionne & Mora, 2007). The SDLC models follow a systematic, step-by-step process designed to develop information systems. Both the four-step SDLC model and seven-step SDLC model establish a series of crucial activities so as to attain the set objectives. In each of the models, the process follows a logical path in which the output of a phase becomes the input in the next phase. The SDLC models comprise of different stakeholders in the project development. They include an IT steering committee in the organization, system analyst, application programmers and the end-users.
A major difference between the seven-step and four-step SDLC model is that the seven-step comprises of seven stages of development whereas the four-step process comprises of four stages. The processes also vary in detailed definition of the stages in each of the models. The seven-step SDLC model thus becomes suitable for the development of complex IT projects, unlike the four-step SDLC model. The seven-step SDLC model also takes a long time to complete when compared to the four-step SDLC model.
However, in the development of some systems, one SDLC model does not meet the needs of the project. In this case, two models can be combined to harness the qualities of a model and minimize the weaknesses of each by incorporating the strengths of the other (Isaias & Issa, 2015).
A variety of SDLC models and frameworks exist in the IT industry, hence meaning the process of selecting an appropriate model may be complicated. However, the different SDLC models provide different benefits to a project; thus the development team should select the model that suits the project needs. The selection of the right SDLC model for the development of an information system plays a core role in the modern business and organizational contexts.
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