The System Development Life Cycle

Structured analysis uses a concept called the system development life cycle (SDLC) to plan and manage the system development process. The SDLC describes activities and functions that all system developers perform , regardless of which approach  they use.

The SDLC model includes the following steps.

1.   Systems  planning

2.    Systems  analysis

3.    Systems  design

4.   Systems implementation

5.   Systems operation, support, and security

Traditionally, the SDLC is pictured as a waterfall model, where the result of each phase, which is called a deliverable or end product, flows sequentially into the next phase. Typically, the adjacent phases interact, as shown by the dotted lines.

System Planning

The system planning phase usually begins with a formal request to the IT department, called a systems request that describe problems or desired changes in an information system or a business process. In many companies, IT systems planning is an integral part of overall business planning. When managers and users develop their business plans, they usually include IT requirements that generate system request.

The purpose of this phase is to perform a preliminary investigation to identify the nature and scope of the business opportunity or problem. The preliminary investigation is a critical step because the outcome will affect the entire development process. A key part of the preliminary investigation is a feasibility study that reviews anticipated costs and benefits and recommends a course of action based on operational, technical, economic, and time factors.

Systems Analysis

The purpose of the systems analysis phase is to build logical model of the new system. The first step is requirements modeling, where you investigate business processes and document what the new system must do. Requirements’ modeling continues the investigation that began during the system planning phase. To understand the system, you perform fact-finding using techniques such as interview, surveys, document review, observation, and sampling. You use the fact-finding results to build business models, data, and process models, and object models.

The end product for the systems analysis phase is the system requirements document. The system requirements document describes management and user requirements, cost and benefits, and outlines alternative development strategies.

Systems Design

The purpose of the systems design phase is to create a blueprint that will satisfy all documented requirements for the system. At this stage, you design the user interface and identify all necessary outputs, inputs, and process. In addition, you design internal and external controls, including computer-based and manual features to guarantee that the system will be reliable, accurate, maintainable, and secure. During the systems design phase, you also determine the application architecture, which shows programmers how to transform the logical design into program modules and code.

The result of this phase is documented in the system design operation and presented to management and users for review and approval. Management and user involvement is critical to avoid any misunderstanding about what the new system will do, how it will do it, and what it will cost.

Systems Implementation

During the systems implementation phase, the new system is constructed. Whether the developers used structured analysis or O-O methods, the procedure is the same-programs are written, tested, and documented, and the system is installed. If the system was purchased as package, systems analysts configure the software and perform any necessary modifications. The objective of the systems implementation phase is to deliver a completely functioning and documented information system.

At the conclusion of this phase, the system is ready for use. Final preparations include converting data to the new system’s files, training users, and performing the actual transition to the new system. The systems implementation phase also includes an assessment, called a system evaluation, to determine whether the system operates properly and if costs and benefits are within expectations.

Systems Operation, Support, and Security

During the system operation, support, and security phase, the IT staffs maintain, enhance, and protect the system. Maintenance changes correct errors and adapt to changes in the environments, such as new tax rates. Enhancements provide new features and benefits the objective during this phase is to maximize return on the IT investment. Security controls safeguard the system from both external and internal threats.

A well-designed system will be secure, reliable, maintainable, and scalable. A scalable design can expand to meet new business requirements and volumes. Information systems development is always a work in progress. Business processes change rapidly, and most information systems need to be updated significantly or replaced after several years of operation.

System Development Guidelines

With experience as systems analysts, you will develop your own style and techniques. Although each project is different, you should consider basic guidelines as you build an information system.

1.   Planning.  Stick to an overall development plan. If you use the SDLC as a framework for systems development, complete the phases in sequence. If you use an O-O methodology, follow a logical series of steps as you define the components.

2.   Involve the Users throughout the Development Process.  Ensure that users are involved in the development process, especially when identifying and modeling system requirements. Modeling and prototyping can help you understand user needs and develop a better system.

3.   Listening is Very Important.  Listen carefully! The best system is the one that meets user needs most effectively. When you interact with users, you must put aside any preconceived notions and listen closely to what they are saying to you. Chapter 3 describes the interview process and contains may tips about getting the most out of face-to-face communication.

4.   Create a Timetable with Major Milestones.  Identify major milestones for project review and assessment. At those milestones, managers and system developers must decide whether to proceed with the project, redo certain task, return to an earlier phase, or terminate the project entirely. The SDLC models require formal assessment of end products and deliverables. O-O analysis involves a continuous modeling process that also requires checkpoint and project review.

5.   Identify Interim Checkpoints.  Establish interim checkpoints between major milestones to ensure that the project remains on schedule. Regardless of the development methodology, the system analyst must keep the project on track and avoid surprises. Create a reasonable number of checkpoints –to many can be burdensome, but too few will not provide adequate control. An example of a checkpoint might be the completion of interviews conducted during a preliminary investigation.

6.   Remain flexible.  Be flexible within the framework of your plan. Systems development is a dynamic process, and overlap  often exist between the phases of systems planning, analysis, design, and implementation, for example, when you investigate a systems request, you begin a fact-finding process that often carries over into the next phase. Similarly, you often start building process models before fact-finding is complete. The ability to overlap phase is especially important when you are working on a system that must be develop rapidly.

7.   Develop Accurate Cost and Benefit Information.  Provide accurate and reliable cost and benefit information. Managers need to know the cost of developing and operating system. At the start of each phase, you must provide specific estimates.

THE INFORMATION TECHNOLOGY DEPARTMENT

The information technology (IT) departments   develop and maintain company information systems. The structure of the IT department varies among companies, as a does its name and placement within the organization. In a small firm, one person might handle all computer support activities and services, whereas a large corporation might require many people with specialized skills to provide information system support.

The IT group provides technical support, which include six main functions: application development, system support and security, user support, database administration, networked administration, and web support. These functions overlap considerably and often have different names in different company.

Application Development

Traditionally, IT departments had an application development   group composed of systems analysts and programmers who handled information system design, development, and implementation. Today, many companies use development teams consisting of users, managers, and IT staff member for those some tasks. A popular model for information systems development is a project-oriented team using RAD or JAD, with IT professionals providing overall coordination, guidance, and technical support.

System Support and Security

Systems support and security provides vital protection and maintenance services for system hardware and software, including enterprise computing systems, networks, transaction processing systems, and corporate IT infrastructure. The system support and security group implements and monitors physical and electronic security hardware, software, and procedures. This group also installs support operating systems. In addition, systems support and security technicians provide technical assistance to other groups in the IT department.

User Support

User support provides users with technical information, training, and productivity support. The user support a function usually is called a help desk or information center (IC). A help desks staff trains users and managers on application software such as e-mail, word processors, spreadsheets, and graphic packages. User support specialists answer questions, troubleshoot problems, and serve as clearinghouse for user problem and solutions.

In many companies, the user support team  also installs and configures software applications that are used within the organization. Although user support specialist coordinate with other technical support areas, their primary focus is user productivity and support for user business process.

Database Administration

Database administration involves database design, management, security, backup, and user access. In small-and medium-sized companies, an IT support person performs those roles in addition to other duties. Regardless of company size, mission-critical database applications require continuous attention and technical support.

Network Administration

Business operation depend on telecommunication networks that enable company-wide information systems. Network administration includes hardware and software maintenance, support, and security. In addition to control user access, network administrators install, configure, manage, monitor, and maintain network applications. Network administration is discussed in more detail in Chapter 8.

Web Support

Web support is the newest technical support function. Web support specialists, often called webmasters, support a company’s Internet and intranet operations. Web support involves design and construction of Web pages, monitoring traffic, managing hardware and software, and linking Web-based applications to the company’s existing information system. Reliable, high-quality Web support is especially critical for companies engaged in e-commerce.