Part-2 System Development
The importance of developing an information system
System development is change the whole of old system to arrange the new system or just repair the present system. The old system need to repair is caused by several matters, such as:
1. Problems
There are several problems that appear in old system, such as:
− Disorganize
Disorganize in old system is caused the old system can't operate appropriately.
− The growth of organization
The growth of organization make we have to create the new system. The grown-up of organization such as:
a. The need for information is arise.
b. The advance of data manufacture
c. Differences of new accountancy principle
2. Opportunities
Increase the equipping of information until the information can used to make a decision.
The opportunities are like: market opportunity, costumer services.
3. Directives
There are some instructions from manager or alteration of government’s law.
The purpose or goal of developing an information system
1. Resolve the problems
2. Reach the Opportunities
3. Implementation the Directives
The organization’s expectations after implementing an information system
1. Performance
It's measured by throughput and response time.
2. Information
Increase the quality of information.
3. Economy
Increase the benefit and discharge the cost.
4. Control
Advance control to detection and do the corrective action.
5. Efficiency
It’s measured by output divide with input.
6. Services
Advance system services.
The principles of developing an information system
1. System is developing for management
2. System is the great investment
Investigate the entire alternative to minimize the lost opportunity cost and to find the great investment. The great investigation must be precious, the investment is has a value if the use of it more effective than the cost to had it. We can use cost-benefit analysis or cost-effectiveness to determine the precious of investment.
3. System need educated person
4. System development life cycle
Provides overall framework for managing systems development process.
5. System development process is must not in series
6. Don’t be afraid to canceled the project
7. System Documentation
System development life cycle models
1. The Waterfall Model
In the waterfall approach, the whole process of software development is divided into separate process phases.
The phases in waterfall model are:
− Requirement
All possible requirements of the system to be developed are captured in this phase.
− Design
Before us starting the actual coding, it is important to understand what we are going to create. The requirement specifications from first phase are studied in this phase and we can prepare the system design.
− Implementation
Activities in this phase: construct, test, train users, and install new system.
− Verification, include in this phase:
Testing: focus in internal logic of software and external function(find the fault and certain the input-output)
Coding is process convert design into language that machine is known use programming language.
− Maintenance: the meaning of maintenance is how we adapt to changes.
2. Iterative Model
1. Adopt sequential linier and prototype model.
2. The project is dividing into small parts. This allows the development team to demonstrate result earlier on in the process and obtain valuable feedback from system users.
3. With iterative model, work activities are repeated.
4. Each iteration refines previous result.
5. Starting from the model/requirements through to the testing/deployment
6. There are a series of mini project for each iteration.
3. Spiral Model
1. Spiral Model is developed to combine the best of the life cycle and prototyping models.
− Use an evolutionary approach suggested by the prototyping paradigm
− Maintains systematic stepwise approach of the life cycle model, but incorporates it in an iterative framework
2. This model adds risk analysis component to minimize risk during development
3. Four major activities in this model are:
− Determine objectives
Objectives are determined, possible obstacles are identified and alternative approach are weighed
− Risk analysis (Identify and resolve risk)
Possible alternatives are examined by the developer and associated risk or problems are identified. Resolution of the risk are evaluated and weighed in the consideration of project continuation.
− Development and Test
Detail requirement are determined and the software piece is developed.
− Planning the next Iteration
The costumer is given an opportunity to analyze the result of the version created in engineering step and to offer feedback to the developer.
Approaches of developing a system
Classical Approach vs Structured Approach
Classical Approach
1. Use System Development Life Cycle phase, but this approach not give the manual how to do the phase.
2. System User is not stay with.
3. The problems that appear if we use this approach are:
Difficult to expand, great of maintenance cost, minimum of success, complicate in implementation.
Structured Approach
1. Use tools like data flow diagram.
2. System user is stay with.
Piecemeal Approach vs Systems Approach
Piecemeal Approach
1. Emphasize in applications or activities.
Systems Approach
1. View the system as integrated element.
2. Emphasize to get a target
Bottom-up Approach vs Top-down Approach
Bottom-up Approach
1. Start from bottom level, which is operational level
2. Bottom approach is classical approach feature.
3. Known as data-analysis
Top-down Approach
1. Start from top level that is strategy planning level.
2. Top-down approach is structured approach feature.
3. Known as decision-analysis.
Total-system Approach vs Modular Approach
Total-system Approach
1. Expand the system together and comprehensive.
2. Total-system Approach is classical approach feature.
Modular Approach
1. Divide the system in simple a part.
2. That expand system is actual.
3. Modular Approach is structured approach feature.
Great-loop Approach vs Evolutionary Approach
Great-loop Approach
1. Expand the system at once using sophisticates technology.
2. High risk and cost.
Evolutionary Approach
1. Appling sophisticates technology for special application.
2. Developed with requirement.
3. Economical and go along with technology development.
The meaning of methodology, method and algorithm
Methodology
Methodology is methods that used in science or comprehensive guidelines to follow for completing every System Development activity.
Method
Method is a systematic way to do something.
Algorithm
Algorithm is the sequence of procedure to resolve the problem.
Three classifications of development methodology
Functional decomposition
Emphasize at dividing a system into small parts or subsystem. This make the system easy to learn, design and applied.
Data-oriented
This methodology emphasizes at characteristic of data that processing and classified at:
1. Data-flow oriented methodologies, based in dividing system into modules according a element data type and behavior of logic module. Include in this methodologies are: SADT (Structured Analysis and Design Technique), Composite Design and SSAD (Structured System Analysis and Design).
2. Data-structured oriented methodologies, emphasize at input-output structure. Include in these methodologies are: JSD (Jakson’s systems development) and Warnier/Orr (W/O)
Prescriptive
Include in these methodologies are:
1. ISDOS (Information System Design and Optimization System),
2. PLEXIS, transformation a statement of high level computer language into executable code.
3. PRIDGE, a complex software that used to analyze and design system, data management, project management and documentation.
4. SDM/70 (System Development Methodology/70)
5. SPECTRUM,
6. SRES (Software Requirement Engineering System) and SREM(Software Development System).
7. Other prescriptive methodologies : Chapin’s approach, DBO (Design By Objective), PAD (Program Analysis Diagram), HOS (Higher Order Software), MSR (Meta Stepwise Refinement) and PDL (Program Design Language).
Tools for developing a system
1. Graphic models
1. HIPO diagram, it’s used in HIPO methodology and other methodology.
2. Data flow diagram, it’s used in structured system analysis and design.
3. Structured chart, it’s used in structured system analysis and design.
4. SADT diagram, it’s used in SADT methodology.
5. Warnier/Orr diagram it’s used in Warnier/Orr methodology.
6. Jakson’s diagram it’s used in Jakson System Development.
2. Charting Tools
− Activity charting: drawing activity, such as:
1. System flowchart
2. Program flowchart
3. Paperwork flowchart
4. Form flowchart
5. Gantt chart
− Layout charting
− Personal relationship charting
Techniques used in developing a system
The techniques that used in developing a system is not only specifically for one methodology, but also it can used in all of methodologies. The techniques that can be used are:
1. Project Management Techniques,
Such as: CPM (Critical Path Method) and PERT (Program Evaluation and Review Technique). It can be used for project scheduling.
2. Fact Finding Techniques
Fact Finding Techniques are techniques can be used for collection data and finding fact in learning system activity. These techniques are:
-Interview
-Observation
-Questionnaires
-Sampling
3. Cost effectiveness analysis/ Cost benefit analysis
4. Meeting Techniques
5. Walkthrough Techniques
The differences of being a system analyst and a programmer
System analyst:
1. Learning the problem and determine the requirement of system user to identify solution of the problem.
2. Be a mediator between system user and programmer especially about their knowledge.
Programmer:
1. Programmer writing the code programs of the application according design which made by system analyst.
2. Programmer’s knowledge is limited by computing technology, computer system, utilities, and programming language.
The knowledge’s a system analyst should posses
1. Knowledge and skills about data manufacture method, computer technology, and computer programming.
2. Knowledge about business in generally
3. Knowledge about quantitative method
4. Problem solving skills
5. Interpersonal communication skills
6. Interpersonal relationship skills
