Systems Development Chapter 6 Learning Objectives Know the characteristics of sy
Fields, Monique, Metro Reporter has reference to this Academic Journal, PHwiki organized this Journal Systems Development Chapter 6 Learning Objectives Know the characteristics of systems development. Underst in addition to what professional systems analysts do. Underst in addition to how program development in addition to system development differ. Learn the major challenges of systems development. Know the nature in addition to phases of the classical systems development cycle (SDLC). Know the nature in addition to development tools used as long as rapid application development (RAD). Know the nature in addition to phases of object-oriented development (OOD) using unified process (UP). Underst in addition to the nature in addition to advantages of extreme programming (XP). Systems Development Fundamentals Systems development is defined as a process as long as creating in addition to maintaining in as long as mation systems. Developing an in as long as mation system involves all five components: hardware, software, data, procedures, in addition to people.
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Systems Development Challenges Systems development is difficult in addition to risky. Many projects are never finished. Some projects finish 200 or 300 percent over budget. Some projects finish on schedule in addition to within budget but do not meet their goals. Difficulties in determining requirements Changes in requirements Scheduling in addition to budgeting difficulties Changing technology Diseconomies of scale Systems Development Processes or Methodologies There are however many systems development processes we are concerned with: Systems development life cycle (SDLC) Rapid application development (RAD) Object-oriented systems development (OOD) Extreme programming (XP) In as long as mation systems differ, no single process works as long as all situations. Systems Development Life Cycle The numbers of phases used by organizations vary. We use five phases. System definition Requirements analysis Component design Implementation System maintenance (fix or enhance)
Figure 6-2 Phases in the SDLC System Definition Phase Tasks Define project Goals in addition to objectives Scopestatement of work Assess feasibility Cost (budget) Schedule Technical Organizational feasibility Form a project team Project manager In-house IT staff Outside consultants in addition to staff (as needed) User representatives (management in addition to staff) Requirement Analysis Phase Tasks The most important phase in the system development process is determining system requirements. If the requirements are wrong, the system will be wrong. If the requirements are determined completely in addition to correctly, then the design in addition to implementation will be easier in addition to more likely to result in success. Seasoned in addition to experienced system analysts know how to conduct interviews to bring such requirements to light.
Obtain User Approval Once the requirements have been specified, the users must review in addition to approve them be as long as e the project continues. The easiest in addition to cheapest time to alter the in as long as mation system is in the requirements phase. Changing a requirement in the implementation phase may require weeks of reworking applications components in addition to the database. Component Design Phase Each of the five components is designed in this stage. The team designs each of the five components by developing alternatives. Each alternative is evaluated against the requirements. Typically the best alternative that meets the requirements is selected. Hardware Design The team determines specifications as long as the hardware that they would want to acquire. The team is not designing hardware. Typically, a large scale company will have some sort of networking infrastructure.
Hardware Networking Alternatives PC or LANs over the public Internet Three separate point-to-point leased lines Lease time on some type of PSDN Create Virtual Private Network (VPN) over the Internet Program Design Depends on the source of the programs Off-the-self-the team must determine c in addition to idate products in addition to evaluate them against requirement Off-the-shelf with alteration programs-the team identifies products to be acquired off-the-shelf in addition to then determines the alterations required. Custom-design programs-the team produces specifications (documentation) as long as writing program code Database Design When constructing a database: Convert the database design to a data model If off-the-shelf database, little design is needed
Procedure Design Procedures must be developed as long as system users in addition to operations personnel to follow. These procedures typically address: Normal operations Backup of transactions in addition to data System failure recovery Design of Job Descriptions Job descriptions are needed as long as both users in addition to operations personnel. New in as long as mation systems may require new jobs. Organizations may have to add new duties in addition to responsibilities due to in as long as mation systems changes in addition to enhancements. Implementation Phase Tasks in this phase are to build, test, in addition to convert the users to the new system. System user training in addition to procedures are verified.
Implementation System Phase Testing System testing consists of testing the integrated components of the system as a complete working system. Test plans are developed based on system requirements in addition to are used to verify that the system works as expected. Testing in addition to retesting consumes huge amounts of labor. Automated testing is used to reduce testing labor in addition to reduces testing time. Many IT professionals work today as testing specialists under Product Quality Assurance (PQA). Beta testing allows future system users to try out the new system on their own. Normally products in the beta test are complete in addition to fully functioning with few errors. Implementation Phase System Conversion There are four ways to implement system conversion: PilotImplement the entire system on a limited portion of the business PhaseNew system is installed in pieces across the organization ParallelNew system runs in parallel with the old system as long as a while PlungeThe old system is turned off in addition to the new system is turned on immediately Maintenance Phase Work done in this phase is to fix the system to work correctly or adapt the system to changes in requirements.
Maintenance Phase Tasks Record requests as long as change System failures Enhancement requests Prioritize requests Failure fixing Patches Service packs Enhancements New releases Problems with the SDLC Systems development seldom works so smooth. There is sometimes a need to crawl back up the waterfall. Difficulty of documenting requirements in a usable way. Scheduling in addition to budgeting is difficult especially as long as large projects with large SDLC phases. Rapid Application Process (RAD) Basic idea is to break up the design in addition to implementation phases of the SDLC into smaller pieces. Design in addition to implement the pieces using as much computer assistance as possible.
RAD Characteristics Design / implement / fix development process Continuous user involvement throughout Extensive use of prototypes Joint Application Design (JAD) CASE Tools Prototypes Another RAD characteristic is the use of prototypes. A prototype is a mock-up of an aspect of the new system. A prototype could be one of the following: Form Report Database query Other elements of the user interface Joint Application Design JAD is another key element of RAD. JAD came about because development wanted to incorporate feedback in addition to testing earlier in the development process. A JAD session is a design meeting of short duration, perhaps an afternoon or a day or two at most. The goal is to keep the scope of the component small enough that the design can be completed in a short period.
CASE in addition to Visual Tools A CASE tool is a computer system to aid in the development of computer programs or systems. CASE tools vary in their features in addition to functions. CASE tools have a repository that contains documents, data, prototypes, in addition to program code as long as the software or system under development. Object-Oriented Systems Development Object-Oriented Development (OOD) came about from the discipline of object-oriented programming. Object-Oriented Programming (OOP) is a discipline as long as designing in addition to writing programs. Unified Modeling Language (UML) is a series of diagramming techniques that facilitates OOP development. Unified Process (UP) was designed as long as use with UML. Extreme Programming An emerging technique as long as developing computer programs Not useful as long as large scale development systems that require business processes in addition to procedures Iterative style in addition to distinguished by: Customer centric Just-in-time-design Paired programming
Figure 6-18 Comparison of Development Techniques Summary Systems development is the process of creating in addition to maintaining in as long as mation systems in addition to are tailor-made. Major challenges of systems development include: Determining requirements Changes in requirements Difficulties in scheduling in addition to budgeting Changing technology Diseconomies of scale Three systems development methodologies are: Systems Development Life Cycle (SDLC) Rapid Application Development (RAD) Object-Oriented Development (OOD) Extreme Programming (XP) is an emerging technique as long as developing computer programs in very short iterations of two weeks or less.
Fields, Monique Metro Reporter
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