The Importance of Developing an Information Systems
1. There are many problems appear of the old systems
2. Damage growth of organization’s
3. The reach for opportunities
4. There are many directives
The Purpose or Goal of Developing an Information System is:
* Analyze the problems
* The reach for opportunities
* Comply the request directives
The Organization’s Expectations after Implementing an Information System
* Performance
* Information
* Economy
* Control
* Efficiency
* Services
The Principles of Developing an Information System :
* System for Management
* The system is a Big investment
* Systems need educate person
* System development life cycle
* System development mustn't well organized
* Don't afraid to cancelled the project
* System Documentation
System development life cycle
1.Waterfall Model
The waterfall model is a sequential one, consisting of the following process areas:
- The requirements phase, in which the requirements for the software are gathered and analyzed, to produce a complete and unambiguous specification of what the software is required to do.
- The architectural design (analysis) phase, where a software architecture for the implementation of the requirements is designed and specified, identifying the components within the software and the relationships between the components.
- The design phase, where the detailed implementation of each component is specified.
- The code and unit test phase, in which each component of the software is coded and tested to verify that it faithfully implements the detailed design.
- The system integration and system test phase, in which the software is integrated to the overall product and tested.
- The acceptance testing phase, where tests are applied and witnessed to validate that the software faithfully implements the specified requirements.
2.Model Spiral
The next step is determined by remaining risks. For example, its performance or user-interface risks are considered more important than the program development risks. The next step may be evolutionary development that involves developing a more detailed prototype for resolving the risks. On the other hand, if the program development risks dominate and previous prototypes have resolved all the user-interface and performance risks; the next step will follow the basic waterfall approach.
The risk driven nature of the spiral model allows it to accommodate any mixture of specification-oriented, prototype-oriented, simulation-oriented or some other approach. An important feature of the model is that each cycle of the spiral is completed by a review, which covers all the products developed during that cycle, including plans for the next cycle. The spiral model works for developed as well as enhancement projects.
In round one, a concept of operation is developed. The objectives are stated more precisely and quantitatively and the cost and other constraints are defined precisely. The risks here are typically whether or not the goals can be met within the constraints. The plan for the next phase will be developed which will involve defining separate activities for the project. In round two the top-level requirements are developed. In succeeding the rounds, the actual development may be done. This is a relatively new model and can encompass different development strategies. In addition to the development activities, it incorporates some of management and planning activities into the model. For high-risk projects this might be a preferred model.
3.Iterative model
The four basic process areas of the iterative model are:
- The requirements phase, in which the requirements for the software are gathered and analyzed. Iteration should eventually result in a requirements phase that produces a complete and final specification of requirements.
- A design phase, in which software architecture and components to meet the requirements are designed; this may be a new design, or an extension of an earlier design.
- An Implementation phase, when the software is coded, integrated and tested.
- A review phase, in which the software is evaluated, the current requirements are reviewed, and changes and additions to requirements proposed.
The design phase develops the architecture that forms the foundation for the system and is critical to the success of the subsequent iterations. For obvious reasons, the design must facilitate change, and be robust enough to support unforeseen, future implementations. For each cycle of the model, a decision has to be made as to whether the software produced by the cycle will be discarded, or kept as a starting point for the next cycle. This approach has been referred to as incremental prototyping. However, the temptation to create a quick prototype that cannot scale-up must be resisted--typically, this is not prototyping, although it could be. The cycle is complete when the requirements have been satisfied, and the release to the customer is made. On some iterations--particularly early ones, a decision may have to be made to abandon the approach and begin anew.
Approach of system Development
1.Classical approach versus structured approach (depends from methodology)
Classical approach is a traditional approach constitute developing on a priority of the rural the system wich is follow the steps of life cycle without good supplied with tools and tehcnics.
The problems that emerge in the classical approach is :
- Developing the software would be hard
This approach not extend tools and technics to developing the system finally software developing process is not directed and difficult to accupation job with the programmers.
- The cost of maintain the system would be expensive
Cost of maintain would be expensive because documentation system less structured and complete.
- The possibility of the faults system
This approach not prepare the manner of system testing then so the possibility of the faults system
- The sucessful of the system not gauaranted
- Would be a lot of problems to applying the system
- Structural approach stared in early 1970 when this approach use tools and techniques that was needed on developing the system witch is it structure defining clearly. By this , complex approach in organizing can be resolve and the result of it will be easy to rear, flexible, satisfied the user, good documentatoin ,on time, on budged for the developer, rising the productivity, and fault free.
2.Piecemeal approach versus systems approach (depend from the target)
- Piecemeal approach is developing system that pressed to an application without give attention to whole organisation.
- System approach pay attention information system as one unity integrated for each application and also pressed on achieving target to the whole organisation.
3.Bottom-up approach versus Top-down approach (depend from the how to determine the needed of system)
- Bottom–up approach started from low organisation level where the level transaction to do. This approach is the characteristic from classic approach.
- Top-Down approach is the opposite from Bottom-Up approach and characteristic from structured approach .
4.Total-system approach versus Modular approach(depend on how does it expand)
- Total-system approach is expand the system comprehensively at the same time and the characteristics from classic approach.
- Modular approach tries to break the complicated system to bezrp simple modulo. That can be easier to understand and to develop. It is the characteristics from structured approach.
5.Great loop approach versus Evolutionary approach(depends on the technology that use)
- Great loop approach is total changed at the same time with sophisticated technology. This change is contain risk too expensive and hard developed.
- Evolutionary approach is only apply the sophisticated technology for application needed.
Method of Development System
Methodology is methods unity, procedure, conception of job, rules and postulats that use by knowledge,art or another diciplines.
Method is a way,technical systematic to do something.
Algoritma is procedure steps to slove the problem.
The Three Classifications of Development methodology
Data-Oriented Methodologies
- Data-flow Oriented Methodologies
- Data-structure Oriented Methodologies
Prescriptive Methodologies
- ISDOS(Information System Design and Optimization System)
- PLEXSYS
- PRIDE
- SDM/70(System Development Methodology/70)
- SPECTRUM
- DBO(Design by Objective)
- PAD
- HOS
- MSR
- PDL
Mention Tools for Developing a system
The Specific Characteristic Graphical Tools for Developing Systems
- HIPO Diagram
- Data Flow Diagram
- Structured Chart
- SADT Diagram
- Warnier/Orr Diagram
- Jakson's Diagram
The General Characteristic Graphical Tools for Developing System
- Activity Charting
- Systems Flowchart
- Program Logic Flowchart
- Detailed Computer Program Flowchart
- Paperwork Flowchart/Form Flowchart
- Database Relation Flowchart
- Process Flowchart
- Gantt Chart
- Layout Charting
- Working Distribution Chart
- Organization Chart
Non-racial Tools for Developing Systems :
- Data Dictionary
- Structured English
- Pseudo code
Techniques that can be used in development system :
1. Project management technique, that is CPM (Critical Path Method) and pert (program evaluation and review technique). This technique is used for project scheduling.
2. Fact finding techniques, that is technique that can be used to gather data and find facts in study existing system, that is:
Interview
Observation
Questionnaire
Sample collecting
3. Cost-effectiveness analysis or cost benefit analysis
4. Technique to run meeting
5. Technique inspection/walkthrough.
Analysis System and Programmer
Analysis ststem is one who analyze to study and identify that probelms and determine user need system.
- Knowledge and skill about data processing technique, computer technology and computer programming.
- Knowledge about business in general.
- Knowledge about quantitative method.
- Trouble-shooting skill.
- Communication skill delivers staff.
- Skill builds connection delivers staff.
Refrences :
1. www.snyders.us/
2.HM, Jogiyanto. Analisis & Desain Sistem Informasi. Yogyakarta: ANDI,2007.
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