The Islamic University of Gaza

The Islamic University of Gaza Accounting Information System Managing the Systems Development Life Cycle Dr. Hisham Madi

Phase 3: Construct the System • The main goal of the construct phase is to design and build working software that is ready to be tested and delivered to its user community. • This involves specifying the outputs, processing procedures, and inputs for the new system

Construct the System Designing System Outputs, Processes, and Inputs • it focuses on developing the system’s input, processing, and output requirements. • When performing design tasks, the design team first focuses on the outputs—not the inputs or processing requirements—of the new system. WHY? • The reason for this is that the most important objective of an AIS is to satisfy users’ needs • Preparing output specifications first lets these requirements dictate the inputs and processing tasks required to produce them

Construct the System System Outputs • The design team will use the data gathered from the prior systems analysis work to help it decide what kinds of outputs are needed as well as the formats that these outputs should have. • It is possible for the design team to merely copy the outputs of an older system. • BUT, it is better the team attempts to create better outputs—that is, design outputs that will better satisfy their users’ information needs than did the old system

Construct the System System Outputs • Outputs may be classified according to which functional area uses them (e.g., marketing, human resources, accounting, or manufacturing) as well as how frequently they must be produced (e.g., daily or weekly). • Where a specific report is not needed on a regular basis, the system should be able to provide it when requested (a demand report) or triggered when a certain condition is met (an exception report).

Construct the System Process Design • After designing the outputs, their next step is to identify the processing procedures required to produce them. • This involves deciding which application programs are necessary and what data processing tasks each program should perform. • There are a large number of tools for modeling computer processes. Among them are the system flowcharts, data flow diagrams, program flowcharts

Construct the System Process Design • the idea of structured, is top-down design, in which system designers begin at the highest level of abstraction and then ‘‘drill down’’ to lower, more detailed levels until the system is completely specified.

Construct the System Designing System Inputs • Once the design team has specified the outputs and processing procedures for a new project. • The design team can think about what data the system must collect to satisfy these output and processing requirements. • Thus, the team must identify and describe each data element in the systems design (e.g., ‘‘alphabetic,’’ ‘‘maximum number of characters,’’ and ‘‘default value’’)

Construct the System Designing System Inputs • After the design team identifies and describes the input data, it can determine the source of each data element. • For example, customer information such as name, address, and telephone numbers may be gathered directly from web screens, and the current date can be accessed from the computer system itself

Deliver the System Testing The Entire System • Programs must be thoroughly tested before being implemented. • All logic procedures should be tested. • Test individual modules with test data containing both “good” and “bad” data.

Deliver the System Testing The Entire System • After testing individual modules, the entire system should be tested as a whole. • The outputs of the system are then reconciled with predetermined results, and the test is documented to provide evidence of the system’s performance.

Deliver the System Documenting • Describes how the system works • Documentation should be provided for: • designers and programmers • Systems designers and programmers need documentation to debug errors and perform maintenance on the system using system flowcharts, and program flowcharts • The system flowchart shows the relationship of input files, programs, and output files. • The program flowchart provides a detailed description of the sequential and logical operation of the program.

Deliver the System Documenting operator documentation • Computer operators use documentation describing how to run the system (run manuals) • run manual include: • The name of the system, such as Purchases System. • The run schedule (daily, weekly, time of day, and so on). • Required hardware devices (tapes, disks, printers, or special hardware).

Deliver the System Documenting User Documentation • Users need documentation describing how to use the system • User tasks include such things as • entering input for transactions, • making inquiries of account balances, • updating accounts, and generating output reports

Deliver the System Documenting User Documentation Tutorials, Help Features Online help features range from simple to sophisticated. A simple help feature may be nothing more than an error message displayed on the screen.

Deliver the System Documenting • accountants and auditors - all of the above

The Role Of Accountants • Most system failures are due to poor designs and improper implementation. • Being a major stakeholder in all financial systems, accountants must apply their expertise in this process to guide and shape the finished system

The Role Of Accountants Provide Technical Expertise • for financial reporting requirements must comply with GAAP. Specify Documentation Standards • Because financial systems must periodically be audited, they must be adequately documented

Commercial Packages Four factors have stimulated the growth of commercial software: • the relatively low cost of general commercial software as compared to customized software; • the emergence of industry-specific vendors who target their software to the needs of particular types of businesses;

Commercial Packages • a growing demand from businesses that are too small to afford an in-house systems development staff; and • the trend toward downsizing of organizational units and the resulting move toward the distributed data processing environment

Commercial Packages Advantages Of Commercial Packages decreased implementation time • Custom systems often take a long time to develop. Months or even years may pass before a custom system can be developed through in-house procedures. • On the other hand, small commercial software systems can be implemented almost immediately upon recognizing a need.

Commercial Packages Advantages Of Commercial Packages Cost • because the cost of commercial software is spread across many users, the unit cost is reduced to a fraction of the cost of a system developed in-house. Reliability • Any system errors that were not discovered during testing that organizations likely uncover shortly after release are corrected

Commercial Packages Disadvantages Of Commercial Packages Independence • Purchasing a vendor-supported system makes the firm dependent on the vendor for maintenance. The Need for Customized Systems • The prime advantage of in-house development is the ability to produce applications to exact specifications.

Commercial Packages Disadvantages Of Commercial Packages The Need for Customized Systems • This advantage also describes a disadvantage of commercial software. Sometimes, the user’s needs are unique and complex, and commercially available software is either too general or too inflexible

Commercial Packages Disadvantages Of Commercial Packages Maintenance • Business information systems undergo frequent changes. If the user’s needs change, it may be difficult or even impossible to modify commercial software

Choosing a Package • Having made the decision to purchase commercial software, the systems development team is now faced with the task of choosing the package that best satisfies the organization’s needs. Step 1: Needs Analysis • As with in-house development, the commercial option begins with an analysis of user needs. • Increase transaction processing capacity. • Reduce the cost of current operations. • Improve user productivity. • Reduce processing errors.

Choosing a Package Step 2: Send Out the Request for Proposals • Systems requirements are summarized in a document called a request for proposal (RFP)that is sent to each prospective vendor. Step 3: Gather Facts • identifying and capture relevant facts about each vendor’s system

Choosing a Package Step 4: Analyze the Findings and Make a Final Selection • The final step in the selection process is to analyze the facts and choose the best package

Phase 5: Maintenance and Support • Maintenance involves both implementing the latest software versions of commercial packages and making in-house modifications to existing systems to accommodate changing user needs. • Maintenance may be relatively trivial, such as modifying an application to produce a new report, or more extensive, such as programming new functionality into a system.

Thank You

The Islamic University of Gaza