Chapter 2 ; System Development

Chapter 2 ; System Development

2.1 The importance of developing an information system
System Development is piled a new system for an old system swing. An old system need improvement because :
1.There are the old system have a problem. That problem in the form of clumsinees in system.
2.To reach a opportunities. In compete, information velocity or efficiency of time, determine strategy is successful or not / plan for reach our chances committed.
3.There are instructions. A new system can appear because there are instructions from superior.

2.2 The purpose or goal of developing an information system
1.For solving problems.
2.For reach opportunities.
3.For fulfilling given instructions.

2.3 The organization’s expectations after implementing an information system
1.Performance. Improvement of a new system work until became more effective. Ex : computer performance of pentium 4 quicker and better than computer of pentium 3.
2.Information. Improvement of information quality. Ex : news in ,www.liputan6.com always up to date and we can believe it.
3.Economy. Improvement of benefit or profit or expense slope. Ex : companies more use information system as a promotion facility than use Sales Promotion Girls (SPG).
4.Control. Improvement of controlling for repair a mistake. Ex : every commodity in supermarket available censor pacifier tools for avoid thief.
5.Efficiency. Improvement of operation efficiency. Ex : by information system, stall officer in charge not to haul files for search compulsory data. It can spend the time efficiently.
6.Services. Improvement of service by system. Ex : a supermarket that before brought commodity code with manually, but now they use a barcode machine.

2.4 The principles of developing an information system
1.Growed system is for management. The usage of this system by management until that system must to back management’s need.
2.Growed system is a big capital investation. So every capital investation most paying attention 2 matter following :
1.We have to check all of alternative. From some alternative must to check for determine the best alternative and the most profitable.
2.The best investation must having value : cost benefit analysis or cost effectiveness analysis.
3.Growed system need skillful someone. Skillful is not graduated of university.
4.Work’s stage and duties, which we must do it in development system process. Involve some personnel in a team form.
5.Development system process must not successive.
6.Don’t fear to cancel project.
7.There must be documentation for guidance in system development.

2.5 System development life cycle models
a. Spiral life cycle model :
The Spiral software development model is a risk-oriented. Spiral software development model may be applicable to projects where:
1.The projects requirements are very difficult
2.Where new technologies are used
The aim of customer communication is to establish effective communication between developer and customer.
The planning objectives are to define resources, project alternatives, time lines and other project related information.
The purpose of the risk analysis phase is to assess both technical and management risks.
The engineering task is to build one or more representations of the application.
The construction and release task – to construct, test, install and provide user support.
The customer evaluation task - to obtain customer feedback based on the evaluation of the software representation created during the engineering stage and implemented during the install stage.
b. Waterfall life cycle model :
Feasibility
The feasibility study is used to determine if the project should get the go-ahead. If the project is to proceed, the feasibility study will produce a project plan and budget estimates for the future stages of development.
Requirement Analysis and Design
Analysis gathers the requirements for the system. This stage includes a detailed study of the business needs of the organization. Options for changing the business process may be considered. Design focuses on high level design like, what programs are needed and how are they going to interact, low-level design, interface design and data design. During these phases, the software's overall structure is defined. Analysis and Design are very crucial in the whole development cycle. Any glitch in the design phase could be very expensive to solve in the later stage of the software development. Much care is taken during this phase. The logical system of the product is developed in this phase.
Implementation
In this phase the designs are translated into code. Computer programs are written using a conventional programming language or an application generator. Programming tools like Compilers, Interpreters, Debuggers are used to generate the code.
Testing
Normally programs are written as a series of individual modules, these subject to separate and detailed test. The system is then tested as a whole. The separate modules are brought together and tested as a complete system. The system is tested to ensure that interfaces between modules work, the system works on the intended platform and with the expected volume of data and that the system does what the user requires.
Maintenance
Inevitably the system will need maintenance. Software will definitely undergo change once it is delivered to the customer. There are many reasons for the change. Change could happen because of some unexpected input values into the system. In addition, the changes in the system could directly affect the software operations. The software should be developed to accommodate changes that could happen during the post implementation period.
c. Prototyping life cycle model :
The Prototyping Model is a Systems Development Method (SDM) in which a prototype (an early approximation of a final system or product) is built, tested, and then reworked as necessary until an acceptable prototype is finally achieved from which the complete system or product can now be developed. There are several steps in the Prototyping Model:
1.The new system requirements are defined in as much detail as possible. This usually involves interviewing a number of users representing all the departments or aspects of the existing system.
2.A preliminary design is created for the new system.
3.A first prototype of the new system is constructed from the preliminary design. This is usually a scaled-down system, and represents an approximation of the characteristics of the final product.
4.The users thoroughly evaluate the first prototype, noting its strengths and weaknesses, what needs to be added, and what should to be removed. The developer collects and analyzes the remarks from the users.
5.The first prototype is modified, based on the comments supplied by the users, and a second prototype of the new system is constructed.
6.The second prototype is evaluated in the same manner as was the first prototype.
7.The preceding steps are iterated as many times as necessary, until the users are satisfied that the prototype represents the final product desired.
8.The final system is constructed, based on the final prototype.
9.The final system is thoroughly evaluated and tested. Routine maintenance is carried out on a continuing basis to prevent large-scale failures and to minimize downtime.

2.6 Approaches of Developing a system
Systems development have some a approach, there are :
1.We can see it from methodology used (classical approach vs structured approach).
2.We can see it from the target, which to be successful for get it (piecemeal approach vs systems approach).
3.We can see it from the method of determine systems need (bottom-up approach vs top-down approach).
4.We can see it from the method for develop that (total-system approach vs modular approach).
5.We can see it from the technology, which they used (great loop approach vs evolutionary approach).

2.7 The meaning of methodology, method and algorithm
Methodology is the branch of philosophy that analyzes the principles and procedures of inquiry in a particular discipline.
Method is a way of doing something, especially a systematic way; implies an orderly logical arrangement (usually in steps).
Algorithm is a precise rule (or set of rules) specifying how to solve some problem.

2.8 Three classifications of development methodology
Functional decomposition methodologies : methodology for solving system in to sub system, which more small than system before.
Data Oriented methodologies : methodology for characteristic of data, which will processed. Methodology to consist of :
1.Data flow oriented methodologies.
2.Data structure oriented methodologies.
Prescriptive methodologies : methodology to consist of :
1.ISDOS (Information System Design and Optimization System).
ISDOS is software. University of Michigan develop ISDOS. The function of ISDOS is to make develop process of information according automatic.
2.SDM/70 (System Development Methodology/70)
SDM/70 is software, which the contains is administration sign for developing system.
3.Etc.

2.9 Tools for developing a system
a. Graph :
1.HIPO Diagram : used at HIPO methodologies.
2.Data Flow Diagram (DFD) : used at structured systems analysis and design methodologies.
3.Structured chart : used at structured systems analysis and design methodologies.
4.SADT Diagram : used at SADT methodologies.
5.Warnier/Orr Diagram : used at Warnier/Orr methodologies.
6.Jakson’s Diagram : used at Jackson System Development methodologies.
b. Flowchart
1.Activity charting
1.System Flowchart
2.Program Flowchart ; Program Logic Flowchart, Detailed Computer Program Flowchart
3.Paperwork Flowchart / From Flowchart
4.Database Relationship Flowchart
5.Process Flowchart
6. Gantt Chart
2.Layout charting
3.Personal Relationship Charting : Working Distribution chart, Organization Chart

2.10 Techniques used in developing a system
a. Project Management Techniques : for Project scheduling. That is : CPM (Critical Path Method) and PERT (Program Evaluation and Review Technique).
b. Fact Finding Technique : in learn a system for collect data and get facts we can use technique.
exp : interview, observation, questionaires, sampling.
c. Cost-effectiveness analysis or cost-benefit analysis.
d. Techniques for performed meeting.
e. Walkthrough Techniques

2.11 The differences of being a system analyst and a programmer and the knowledge a system analyst should posses
System analyst :
1.Responsibility of system analyst not only to make computer program but also all of system.
2. System analyst must have a wide knowledge not only in computer technology but also in application field.
3.etc.
Programmer :
1.Responsibility of system programmer is to make computer program.
2.The skill of programmer only to computer technology, computer system, utilities, and programs languages which they need.
3.etc.
System analyst must have wide knowledge and special skill, there are :
1.Knowledge and skill about processing technique and computer programmer.
2.Ability about general business.
3.Ability about quantitative method.
4.The skill to solving a problem.
5.The skill to communication between personnel
6.The skill to build contact between personnel.

Reference :
Jogiyanto H.M. Analisis dan Desain Sistem Informasi. Yogyakarta ; Penerbit ANDI, 2005.
http://www.stsc.hill.af.mil/resources/tech_docs/gsam3/chap5.pdf
http://wordnetweb.princeton.edu/perl/webwn?s=methodology
http://wordnetweb.princeton.edu/perl/webwn?s=algorithm
http://wordnetweb.princeton.edu/perl/webwn?s=method