Chapter 13: Systems Design, Implementation, Maintenance, and Review
Agenda • Systems Design • Systems Implementation • Systems Maintenance • Systems Review • Systems Performance Measurement
Systems Design A phase in the development of an IS system that answers the question “How will the information system do what it must do to obtain a solution to a problem?” • Logical Systems Design describes the functional requirements of a systems. • Physical Systems Design specifies the characteristics of the system components necessary to put the logical design into action.
Logical Design Elements • Output design describes types, format, content and frequency of all outputs from the system • Inputdesign specifies the types, format, content and frequency of input data • Processingdesign defines the manipulation required for processing • Fileanddatabasedesign specifies files and databases (i.e., ER diagrams) • Telecommunicationsdesign (i.e., topologies) • Proceduresdesign to operate the system • Controlsandsecuritydesign (i.e., disaster recovery) • Personnelandjobdesign (i.e., job titles, positions)
Physical Design Elements • Hardwaredesign specifies all computer equipment • Softwaredesign specifies all software capabilities • Databasedesign specifies the type, structure, and function of the database • Telecommunicationsdesign includes the characteristics of the communications software, media, and devices • Personneldesign specifies the background and experience of individuals • Proceduresandcontroldesign specifies how each application is to run and what has to be done to minimize the potential for crime and fraud
Design of Procedures for Signing On • Sign-on Procedures are safeguards needed for an individual to gain access to computer resources • Systems Sign-on allows user to gain access to the computer system • Application Sign-on permits the user to start and use a particular application
Design for Interactive Processing People interact directly with the processing component of the system • In menu-driven systems, users pick what they want to do from a list of alternatives • Help Facility is a tool that aids a user who is having difficulty understanding what is happening or what type of response is expected • Restart Procedures are procedures that make it very simple for an individual to restart an application from where one left off • Lookup Tables are tables within an application that simplifies and shortens data entry
Design for Interactive Dialogue • Dialogue is the series of messages and prompts communicated between the system and the user. These design elements should be considered during systems design: • Clarity • Response time • Consistency • Format • Jargon
Design for Preventing, Detecting, and Correcting Errors Best time to deal with potential errors is at the beginning of design rather than in the late part of design, or during implementation.
Design for Emergency Alternative Procedures and Disaster Recovery Disaster Recovery is the implementation of the disaster plan. • Hardware Backup • Hot Site is a duplicate computer system that is operational and ready for use • ColdSite (Shell) is a computer environment that includes rooms, electrical service, telecommunications links, data storage devices • Software and database backup • Selectivebackup copies of only certain files • Incrementalbackup copies all files changed during the last few days or the last week • ImageLog is a separate file that contains only changes to applications • Telecommunications backup • Personnel backup • Security, fraud, and the invasion of privacy
Systems Controls • System controls are procedures to maintain data security and can help prevent: • Computer misuse • Crime • Fraud • Deterrence Controls are rules that prevent problems before they occur (input, output, processing, telecommunication, personal controls) • Information system departments are closed shops when only authorized operators can run the computers • In open shops, non-operators, such as programmers and systems analysts, are authorized to run the computers
Evaluation Techniques • In Group Consensus, a decision-making group is appointed and given the responsibility of making the final evaluation and selection • Cost/BenefitAnalysis lists the costs and benefits of each proposed system • BenchmarkTest is an examination that compares computer systems operating under the same conditions • In PointEvaluation, each evaluation factor is assigned a weight, in percentage points, based on importance; the system with the greatest total score is selected.
Design Report The Design Report reflects the decisions made for system design and prepares the way for systems implementation. 22
Systems Implementation Systems Implementation includes: • Hardware/Software acquisition or development • User preparation • Hiring and training of personnel • Site and data preparation • Installation • Testing • Start-up • User acceptance. 23
The Make-or-Buy Software Decision • Building Own Software • IS educated staff • Buying Software • Review needs of requirements • Acquire software • Modify or customize software • Acquire software interfaces • Test and accept the software • Maintain the software and make necessary modifications 24
Programming Life Cycle Programming Life Cycle is a series of steps and planned activities developed to maximize the likelihood of developing good software: • Language selection • Program coding • Testing and debugging • Developing documentation • Implementation or conversion 26
Documentation • Technical Documentation • Used by computer operators to execute the program and by analysts and programmers in case there are problems with the program or if the program needs modification. • User Documentation • Developed for the individuals who use the program. This type of documentation shows users, in easy-to-understand terms, how the program can and should be used. 27
Tools and Techniques for Software Development • Structured design breaks a large, difficult problem into smaller problems, each simple enough to manage and solve independently • Structured Programming a way of developing code that provides structure within the program so that testing and maintenance tasks are facilitated. • Object-Oriented Development is the development of a collection of existing modules of code or objects than can be used across any number of applications without being rewritten. • Computer Aided Software Engineering (CASE) • Cross-Platform Development allows programmers to develop programs that can run on computer systems having different hardware and operating systems • Integrated Development Environments (IDEs) are software packages that combine the tools needed for programming with a programming language into one integrated package • A Structured Walkthrough is a planned and pre-announced review of the progress of a program module, a structure chart, or a human procedure
Types of Testing Testing of individual programs. Testing the entire system of programs. Testing the application with a large amount of data. Testing all related systems together. Conducting any tests required by the user.
Start-Up Approaches Start-Up Approach Procedures that begin with the final tested information system; when start-up is finished, the system will be fully operational.
Reasons for Maintenance Systems Maintenance involves checking, changing, and enhancing the system to make it more useful in achieving user and organizational goals. • Changes in business processes • New requests from stakeholders, users, and managers • Bugs or errors in the program • Technical and hardware problems • Corporate mergers and acquisitions • Government regulations • Change in operating system or hardware on which the application runs 38
Type of Maintenance • Slipstream Upgrade is a minor upgrade not worth announcing. • A Patch is a minor change to correct a problem or make a small enhancement. • A Release is a significant program change that often requires changes in the documentation. • A Version is a major program change, typically encompassing many new features. 39
Systems Review • Systems Review is the process of analyzing systems to make sure they are operating as intended. • An Event-Driven Review is triggered by a problem or opportunity such as an error, a corporate merger, or a new market for products • A Time-Driven Review is a review of all systems that is performed after a specified amount of time. 42
Systems Performance Measurement • Systems Performance Measurement is a systems review that involves monitoring the system -- the number of errors encountered, the amount of memory required, the amount of processing or CPU time needed, and other problems. • System Performance Products are products developed to measure all components of the computer-based information system, including hardware, software, database, telecommunications, and network systems. 44
Systems Development Alternatives • Request for proposal • Vendor evaluation • Reliability • Financial stability • Service • Maintenance • Training
Points to Remember • Systems Design • Systems Implementation • Systems Maintenance • Systems Review • Systems Performance Measurement
Pop Quiz • Name the design to describe the functional requirements of a systems. • Name the design to specify the characteristics of the system components. • Name the design to specify the characteristics of the communications software, media, and devices. • Name the procedures to safeguard the access to computer resources. • Name two backup methods for hardware equipments. • Name three backup methods for software programs and database. • Name the evaluation technique using a evaluation factor based on the importance. • Name three financial options to acquire systems. • Name the review triggered by a problem or opportunity. • Name the systems review to monitor the system.
Pop Quiz Answer • Name the design to describe the functional requirements of a systems. Logical • Name the design to specify the characteristics of the system components. Physical • Name the design to specify the characteristics of the communications software, media, and devices. Telecommunication • Name the procedures to safeguard the access to computer resources. Sign on • Name two backup methods for hardware equipments. Hot site, cold site • Name three backup methods for software programs and database. Selective, incremental, image • Name the evaluation technique using a evaluation factor based on the importance. Point evaluation • Name three financial options to acquire systems. Buy, lease, rent • Name the review triggered by a problem or opportunity. Event driven • Name the systems review to monitor the system. System performance measurement