The systems life cycle is the oldest method for building information systems. The life cycle methodology is a phased approach to building a system, dividing systems development into formal stages, as illustrated in Figure 13.9. Systems development specialists have different opinions on how to partition the systems-building stages, but they roughly correspond to the stages of systems development we have just described.
The systems life cycle methodology maintains a formal division of labor between end users and information systems specialists. Technical specialists, such as systems analysts and programmers, are responsible for much of the systems analysis, design, and implementation work; end users are limited to providing information requirements and reviewing the technical staff’s work.The life cycle also emphasizes formal specifications and paperwork, so many
documents are generated during the course of a systems project.
The systems life cycle is still used for building large complex systems that require a rigorous and formal requirements analysis, predefined specifications, and tight controls over the system-building process. However, the systems life cycle approach can be costly, time-consuming, and
The systems life cycle methodology maintains a formal division of labor between end users and information systems specialists. Technical specialists, such as systems analysts and programmers, are responsible for much of the systems analysis, design, and implementation work; end users are limited to providing information requirements and reviewing the technical staff’s work.The life cycle also emphasizes formal specifications and paperwork, so many
documents are generated during the course of a systems project.
The systems life cycle is still used for building large complex systems that require a rigorous and formal requirements analysis, predefined specifications, and tight controls over the system-building process. However, the systems life cycle approach can be costly, time-consuming, and
inflexible. Although systems builders can go back and forth among stages in the life cycle, the systems life cycle is predominantly a “waterfall” approach in which tasks in one stage are completed before work for the next stage begins. Activities can be repeated, but volumes of new documents must be generated and steps retraced if requirements and specifications need to be revised. This encourages freezing of specifications relatively early in the development process. The life cycle approach is also not suitable for many small desktop systems, which tend to be less structured and moreindividualized.
PROTOTYPING
Prototyping consists of building an experimental system rapidly and inexpensively for end users to evaluate. By interacting with the prototype, users can get a better idea of their information requirements. The prototype endorsed by the users can be used as a template to create the final system. The prototype is a working version of an information system or part of the system, but it is meant to be only a preliminary model. Once operational, the prototype will be further refined until it conforms precisely to users’ requirements. Once the design has been finalized, the prototype can be converted to a polished production system.
PROTOTYPING
Prototyping consists of building an experimental system rapidly and inexpensively for end users to evaluate. By interacting with the prototype, users can get a better idea of their information requirements. The prototype endorsed by the users can be used as a template to create the final system. The prototype is a working version of an information system or part of the system, but it is meant to be only a preliminary model. Once operational, the prototype will be further refined until it conforms precisely to users’ requirements. Once the design has been finalized, the prototype can be converted to a polished production system.
The process of building a preliminary design, trying it out, refining it, and trying again has been called an iterative process of systems development because the steps required to build a system can be repeated over and over again. Prototyping is more explicitly iterative than the conventional life cycle, and it actively promotes system design changes. It has been said that prototyping replaces unplanned rework with planned iteration, with each version more accurately reflecting users’ requirements.
Steps in Prototyping
Figure 13.10 shows a four-step model of the prototyping process, which consists of the following:
Step 1: Identify the user’s basic requirements. The systems designer (usually an information systems specialist) works with the user only long enough tocapture the user’s basic information needs.
Steps in Prototyping
Figure 13.10 shows a four-step model of the prototyping process, which consists of the following:
Step 1: Identify the user’s basic requirements. The systems designer (usually an information systems specialist) works with the user only long enough tocapture the user’s basic information needs.
Step 2: Develop an initial prototype. The systems designer creates a working prototype quickly, using tools for rapidly generating software.
Step 3: Use the prototype. The user is encouraged to work with the system to determine how well the prototype meets his or her needs and to makesuggestions for improving the prototype.
Step 4: Revise and enhance the prototype. The system builder notes all changes the user requests and refines the prototype accordingly. After the prototype has been revised, the cycle returns to Step 3. Steps 3 and 4 are repeated until the user is satisfied.
When no more iterations are required, the approved prototype then becomes an operational prototype that furnishes the final specifications for the application. Sometimes the prototype is adopted as the production version of the system.
Advantages and Disadvantages of Prototyping
Prototyping is most useful when there is some uncertainty about requirements or design solutions and often used for designing an information system’s end-user interface (the part of the system with which end users interact,
When no more iterations are required, the approved prototype then becomes an operational prototype that furnishes the final specifications for the application. Sometimes the prototype is adopted as the production version of the system.
Advantages and Disadvantages of Prototyping
Prototyping is most useful when there is some uncertainty about requirements or design solutions and often used for designing an information system’s end-user interface (the part of the system with which end users interact,
such as online display and data entry screens, reports, or Web pages). Because prototyping encourages intense end-user involvement throughout the systems development life cycle, it is more likely to produce systems that fulfill userrequirements. However, rapid prototyping can gloss over essential steps in systems development. If the completed prototype works reasonably well, management may not see the need for reprogramming, redesign, or full documentation and testing to build a polished production system. Some of these hastily constructed systems may not easily accommodate large quantities of data or a large number of users in a production environment.
END-USER DEVELOPMENT
Some types of information systems can be developed by end users with little or no formal assistance from technical specialists. This phenomenon is called end-user development. A series of software tools categorized as fourth-generation languages makes this possible. Fourth-generation languages are software tools that enable end users to create reports or develop software applications with minimal or no technical assistance. Some of these fourth- generation tools also enhance professional programmers’ productivity.
END-USER DEVELOPMENT
Some types of information systems can be developed by end users with little or no formal assistance from technical specialists. This phenomenon is called end-user development. A series of software tools categorized as fourth-generation languages makes this possible. Fourth-generation languages are software tools that enable end users to create reports or develop software applications with minimal or no technical assistance. Some of these fourth- generation tools also enhance professional programmers’ productivity.
Fourth-generation languages tend to be nonprocedural, or less procedural, than conventional programming languages. Procedural languages require specification of the sequence of steps, or procedures, that tell the computer what to do and how to do it. Nonprocedural languages need only specify what has to be accomplished rather than provide details about how to carry out the task. Table 13.3 shows that there are seven categories of fourth-generation languages: PC software tools, query languages, report generators, graphics languages, application generators, application software packages, and very highlevel programming languages. The table shows the tools ordered in terms of ease of use by nonprogramming end users. End users are most likely to workwith PC software tools and query languages. Query languages are software tools that provide immediate online answers to requests for information that are not predefined, such as “Who are the highest-performing sales representatives?” Query languages are often tied to data management software and todatabase management systems
On the whole, end-user-developed systems can be completed more rapidly than those developed through the conventional systems life cycle. Allowing users to specify their own business needs improves requirements gathering and often leads to a higher level of user involvement and satisfaction with thesystem. However, fourth-generation tools still cannot replace conventional tools.
On the whole, end-user-developed systems can be completed more rapidly than those developed through the conventional systems life cycle. Allowing users to specify their own business needs improves requirements gathering and often leads to a higher level of user involvement and satisfaction with thesystem. However, fourth-generation tools still cannot replace conventional tools.
for some business applications because they cannot easily handle the processing of large numbers of transactions or applications with extensive procedural logic and updating requirements. End-user computing also poses organizational risks because it occurs outside of traditional mechanisms for information systems management and control. When systems are created rapidly, without a formal development methodology, testing and documentation may be inadequate. Control over data can be lost in systems outside the traditional information systems department. To help organizations maximize the benefits of end-user applications development, management should control the development of end-user applications by requiring cost justification of end-user information system projects and by establishing hardware, software, and quality standards foruser-developed applications.
No comments:
Post a Comment