LAN-related skills and experience.
Simon & Taylor, Inc., is an equal opportunity employer.
E-mail your resume to HR@simontaylor.com.
FIGURE 1-8 A job advertisement for a systems analyst.
When developing information systems to deal with problems such as these, an organization and its systems analysts have several options: They can go to an in- formation technology services firm, such as Accenture or EDS, an HP Company, to have the system developed for them; they can buy the system off the shelf; they can implement an enterprise-wide system from a company such as SAP; they can obtain open-source software; or they can use in-house staff to develop the sys- tem. Alternatively, the organization can decide to outsource system development and operation. All of these options are discussed in detail in Chapter 2.
Developing Information Systems and the Systems Development Life Cycle Organizations use a standard set of steps, called a systems development methodology, to develop and support their information systems. Like many processes, the development of information systems often follows a life cycle. For example, a commercial product, such as a Nike sneaker or a Honda car, follows a life cycle: It is created, tested, and introduced to the market. Its sales increase, peak, and decline. Finally, the product is removed from the market and is replaced by something else. The systems development life cycle (SDLC) is a common methodology for systems development in many organizations. It marks the phases or steps of information systems development: Someone has an idea for an information system and what it should do. The organization that will use the system decides to devote the necessary resources to acquiring it. A careful study is done of how the organization currently handles the work the system will support. Professionals develop a strategy for designing the new sys- tem, which is then either built or purchased. Once complete, the system is in- stalled in the organization, and after proper training, the users begin to incorporate the new system into their daily work. Every organization uses a slightly different life-cycle model to model these steps, with anywhere from three to almost twenty identifiable phases. In this book, we highlight four SDLC
Chapter 1 The Systems Development Environment 13
steps: (1) planning and selection, (2) analysis, (3) design, and (4) implementa- tion and operation (see Figure 1-9).
Although any life cycle appears at first glance to be a sequentially ordered set of phases, it actually is not. The specific steps and their sequence are meant to be adapted as required for a project. For example, in any given SDLC phase, the project can return to an earlier phase, if necessary. Similarly, if a commercial product does not perform well just after its introduction, it may be temporar- ily removed from the market and improved before being reintroduced. In the systems development life cycle, it is also possible to complete some activities in one phase in parallel with some activities of another phase. Sometimes the life cycle is iterative; that is, phases are repeated as required until an accept- able system is found. Some systems analysts consider the life cycle to be a spiral, in which we constantly cycle through the phases at different levels of detail, as illustrated in Figure 1-10. The circular nature of the life-cycle dia- gram in Figure 1-10 illustrates how the end of the useful life of one system
Systems Planning and
Systems Implementation and Operation SDLC
FIGURE 1-9 The systems development life cycle (SDLC).
Construction and Release
FIGURE 1-10 Evolutionary model SDLC.
Systems analysis Phase of the SDLC in which the current system is studied and alternative replacement systems are proposed.
Systems planning and selection The first phase of the SDLC, in which an organization’s total information system needs are analyzed and arranged, and in which a potential information systems project is identified and an argument for continuing or not continuing with the project is presented.
14 Part I Foundations for Systems Development
leads to the beginning of another project that will replace the existing system altogether. However conceived, the systems development life cycle used in an organization is an orderly set of activities conducted and planned for each development project. The skills required of a systems analyst apply to all life- cycle models.
Every medium-to-large corporation, such as Wal-Mart, and every custom soft- ware producer, such as SAP, will have its own specific, detailed life cycle or sys- tems development methodology in place. Even if a particular methodology does not look like a cycle, many of the SDLC steps are performed, and SDLC tech- niques and tools are used. This book follows a generic SDLC model, as illus- trated in Figure 1-9. We use this SDLC as an example of methodology and a way to think about systems analysis and design. You can apply this methodology to almost any life cycle. As we describe this SDLC throughout the book, it becomes clear that each phase has specific outcomes and deliverables that feed impor- tant information to other phases. At the end of each phase (and sometimes within phases for intermediate steps), a systems development project reaches a milestone. Then, as deliverables are produced, they are often reviewed by parties outside the project team, including managers and executives.
Phase 1: Systems Planning and Selection The first phase in the SDLC, systems planning and selection, has two pri- mary activities. First, someone identifies the need for a new or enhanced sys- tem. Information needs of the organization are examined, and projects to meet these needs are identified. The organization’s information system needs may re- sult from:
� Requests to deal with problems in current procedures
� The desire to perform additional tasks
� The realization that information technology could be used to capitalize on an existing opportunity
The systems analyst prioritizes and translates the needs into a written plan for the information systems (IS) department, including a schedule for developing new major systems. Requests for new systems spring from users who need new or enhanced systems. During the systems planning and selection phase, an organization determines whether resources should be devoted to the develop- ment or enhancement of each information system under consideration. A feasibility study is conducted before the second phase of the SDLC to deter- mine the economic and organizational impact of the system.
Phase 2: Systems Analysis The second phase of the systems development life cycle is systems analysis. During this phase, the analyst thoroughly studies the organization’s current
The second task in the systems planning and selection phase is to investigate the system and determine the proposed system’s scope. The team of systems analysts then produces a specific plan for the proposed project for the team to follow. This baseline project plan customizes the standardized SDLC and speci- fies the time and resources needed for its execution. The formal definition of a project is based on the likelihood that the organization’s IS department is able to develop a system that will solve the problem or exploit the opportunity and determine whether the costs of developing the system outweigh the possible benefits. The final presentation to the organization’s management of the plan for proceeding with the subsequent project phases is usually made by the project leader and other team members.
Systems design Phase of the SDLC in which the system chosen for development in systems analysis is first described independently of any computer platform, (logical design) and is then transformed into technology-specific details (physical design) from which all programming and system construction can be accomplished.
Chapter 1 The Systems Development Environment 15
procedures and the information systems used to perform tasks such as general ledger, shipping, order entry, machine scheduling, and payroll. Analysis has several subphases. The first subphase involves determining the requirements of the system. In this subphase, you and other analysts work with users to determine what the users want from a proposed system. This subphase involves a careful study of any current systems, manual and computerized, that might be replaced or enhanced as part of this project. Next, you study the requirements and structure them according to their interrelationships, eliminating any redundancies. As part of structuring, you generate alternative initial designs to match the requirements. Then you compare these alternatives to determine which best meets the requirements within the cost, labor, and technical levels the organization is willing to commit to the development process. The output of the analysis phase is a description of the alternative solution recommended by the analysis team. Once the recommendation is accepted by the organization, you can make plans to acquire any hardware and system software necessary to build or operate the system as proposed.
Phase 3: Systems Design The third phase of the SDLC is called systems design. During systems design, analysts convert the description of the recommended alternative solution into logical and then physical system specifications. You must design all aspects of the system from input and output screens to reports, databases, and computer processes.
Logical design is not tied to any specific hardware and systems software plat- form. Theoretically, the system you design could be implemented on any hardware and systems software. Logical design concentrates on the business aspects of the system; that is, how the system will impact the functional units within the organization. Figure 1-11 shows both the logical design for a product and its physical design, side by side, for comparison. You can see from the comparison that many specific decisions had to be made to move from the logical model to the physical product. The situation is similar in information systems design.
In physical design, you turn the logical design into physical, or technical, spec- ifications. For example, you must convert diagrams that map the origin, flow, and processing of data in a system into a structured systems design that can then be broken down into smaller and smaller units for conversion to instruc- tions written in a programming language. You design the various parts of the system to perform the physical operations necessary to facilitate data capture, processing, and information output. During physical design, the analyst team decides which programming languages the computer instructions will be writ- ten in, which database systems and file structures will be used for the data, and which hardware platform, operating system, and network environment the sys- tem will run under. These decisions finalize the hardware and software plans initiated at the end of the analysis phase. Now you can acquire any new tech- nology not already present in the organization. The final product of the design phase is the physical system specifications, presented in a form, such as a dia- gram or written report, ready to be turned over to programmers and other sys- tem builders for construction.
Phase 4: Systems Implementation and Operation The final phase of the SDLC is a two-step process: systems implementation and operation. During systems implementation and operation, you turn sys- tem specifications into a working system that is tested and then put into use. Implementation includes coding, testing, and installation. During coding, programmers write the programs that make up the system. During testing, programmers and analysts test individual programs and the entire system in
Systems implementation and operation Final phase of the SDLC, in which the information system is coded, tested, and installed in the organization, and in which the information system is systematically repaired and improved.
16 Part I Foundations for Systems Development
FIGURE 1-11 The difference between logical design and physical design: (A) A skateboard ramp blueprint (logical design), (B) A skateboard ramp (physical design).
Source: http://www.tumyeto.com/ tydu/skatebrd/organizations/ plans/14pipe.jpg; www.tumyeto .com/tydu/skatebrd/ organizations/iuscblue.html (accessed September 16, 1999). Reprinted by permission of the International Association of Skateboard Companies.
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order to find and correct errors. During installation, the new system becomes a part of the daily activities of the organization. Application software is installed, or loaded, on existing or new hardware; then users are introduced to the new system and trained. Begin planning for both testing and installation as early as the project planning and selection phase, because they both require extensive analysis in order to develop exactly the right approach.
Systems implementation activities also include initial user support such as the finalization of documentation, training programs, and ongoing user assistance. Note that documentation and training programs are finalized during implementation; documentation is produced throughout the life cycle, and training (and education) occurs from the inception of a project. Systems
TABLE 1-1: Products of the SDLC Phases
Phase Products, Outputs, or Deliverables
Systems planning and selection Priorities for systems and projects
Architecture for data, networks, hardware, and IS management
Detailed work plan for selected project
Specification of system scope
System justification or business case
Systems analysis Description of current system
General recommendation on how to fix, enhance, or replace current system
Explanation of alternative systems and justification for chosen alternative
Acquisition plan for new technology
Systems design Detailed specifications of all system elements
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