System development can mean to compile a new system to replace a whole old ones system or to improve or to repair the system. Mentioned matter can be caused of several things:
1. There are problems in old systems
First we can see in old systems don’t operate is matching with the one which expected and two mistake which do not be intended which also can cause the truth of data become less guaranteed.
2. To reach Opportunities
In a state of market compete, efficiency of information very determining success or failure of plans and strategy which have been made arrangements for to reach for existing opportunity. Because that information can support in course of decision making to conducted by upstairs management.
3. Existence of Instruction
Compilation of new system earn also happened caused of instruction upstairs management level or from outside organization.
B. Purpose of Systems Development
We can meet the purpose or goal of developing information system such as: - to solving some problems - reach for opportunity - fulfilling given instruction
C. The organization's expectations after implementing an information system
After developing new system, expected improvement in new system. This improvement relate to PIECES, that is:
• Performance, the improvement of performance in a new system make the system will be effective. Performance can be measured from throughput and response time. Throughput is the amount of work which can be done certain in a moment and and response time is time mean which delay between two transactions.
• Information, improvement of quality of presented information.
• Economic, the improvement of benefits and advantages or decreasing cost that happened.
Control, improvement of controlling for detecting and repairing some mistake and also insincerity.
• Efficiency, improvement of operating efficiency and use resources to operate of systems with extravagance of minimum.
• Service, improvement of service given by system.
D. The principles of developing an information system
1. System for management
System must to earn to support requirement needed by management.
2. System is big capital investment
Developed systems need capital which by dozens, more than anything else if using recent technology. Hence each capital invesment have to consider two matter following :
a. Investigation of all alternative ( minimizing missing cost opportunity) Require to be done the investigation from existing alternative, where will invesment, how many advantage if chose that alternative compared to other alternative so that the alternative become most beneficial or best alternative.
b. Best invesment have to assess.
Good investment has to be valuable. The best chosen investment of course not represent most beneficial. Investment told to profit if its benefit or result of returning is bigger than expense to obtaining it.
3. System need educated people
Educated non meaning a student, but can also with on-the-job-training to use system.
4. Step work and jobs for process of systems development
Before process of system development doing, hence must to be made beforehand schedule work to determine job steps. System Development Life Cycle generally show steps work and job duties which must be do.
5. Process of systems development don’t must to step by step.
This principle seen to be oppose against number principle four, but do not that way. Step work can just doing together, that is when ones step job done also can do other step work hence execution of step work become at a time. This matter is done to be process is continue without one step work is finish. ”Remember time is money “.
6. Don’t fear to canceled projects.
Hence the system development process better be canceled because later will permeate fund which is more with result of which no advantage. This will fritter cost.
7. There must be documentation
Documentation of system development there must be. This documentation is made not after system finish but when processing or developing system do. So that this documentation can be used as tools communications between system analyst with user.
E. Systems Development Life Cycle
1. WaterfallModel
The image below is the classic Waterfall model methodology, which is the first SDLC method and it describes the various phases involved in development.
Requirement
At this phase happened is gathering the requirement of system base. The examples are software, human being, and database. This phase also include, gathering of requirement at strategic business storey level and business area storey level.
Design
In system design functions and operations are described in detail, including screen layouts, business rules, process diagrams and other documentation. The output of this stage will describe the new system as a collection of modules or subsystems.
Implementation
Design have to be translated into machine language form. The making of code step reside in this phase. If the design completely done, making the code can be finished mechanically.
Verification
After made the program code, program examination is started. Examination process focus at internal logic software, examination to find mistake and ascertain input is limited that will give result of appropriate actual.
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.
2. Iterative model
In that picture we can see about software development, iterative is used to describe a heuristic planning and development process where an application is developed in small sections called iterations. Each iteration is reviewed and critiqued by the software team and potential end-users; insights gained from the critique of iteration are used to determine the next step in development. Data models or sequence diagrams, which are often used to map out iterations, keep track of what has been tried, approved, or discarded, and eventually serve as a kind of blueprint for the final product.
3. Spiral model
The steps in the spiral model can be generalized as follows:
The new system requirements are defined in as much detail as possible. This usually involves interviewing a number of users representing all the external or internal users and other aspects of the existing system. Than A preliminary design is created for the new system. Second 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.After that A second prototype is evolved by a fourfold procedure: (1) evaluating the first prototype in terms of its strengths, weaknesses, and risks; (2) defining the requirements of the second prototype; (3) planning and designing the second prototype; (4) constructing and testing the second prototype. the customer's option, the entire project can be aborted if the risk is deemed too great. The existing prototype is evaluated in the same manner as was the previous prototype, and, if necessary, another prototype is developed from it according to the fourfold procedure outlined above. And 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. Besides at this phase, the customer / client have to be trained by the way of using it.
F. Approach of System Development There are several approaches to developing a system, that is:
1. Classical approach is an approach of developing a system that follow steps at system life cycle without supplied with tools and techniques.
2. Structured approach equipped with tools and techniques that wanted in system development, so that the end result from system which developed be got system the structure will be defined well and clear.
Piecemeal approach vs. system approach Piecemeal approach will only emphasize at an just application or activity. This approach will only attention target of that just application or activity without seeing target of is overall of organization. Total-system approach is the approach which developing a system together according to comprehensive. This approach less synchronized for complex system, because will be difficult be developed. This approach is feature classic approaches. Modular Approach tries to divide complex system to simple some part, so that system easier will be understood and developed. Furthermore consequence system can be developed of time that planned, easy understood by system user and easy to maintain. This approach is feature structured approaches.
G. The meaning of methodology, method and algorithm
We know there are approaches in developing a system. Now how to do these approaches? To developing a system, it is required by methodologies. Methodology are utilized methods, procedures, professions concept, rules and postulates that used by a science, art or the other. Method is a way of systematic technique to do something. And algorithm is medley procedural to solve problems.
H. The classifications of development methodology
Three classifications of development methodology:
• A. Functional decomposition methodologies Functional decomposition is emphasizing to divide a system becomes subsystem. There are the include in this group methodologies such as:
1. HIPO
2. Stepwise refinement
3. Information hiding.
• B. Data-oriented methodologies Data-oriented is emphasizing on processed data characteristic. This approach can be grouped in two:
a. Data-flow oriented: based on dividing system to modules pursuant to elements data types and logic behavior of these modules in system. There are the include in this group methodologies such as SADT (Structured Analysis and Design Techniques), Composite Design.
b. Data structure oriented: emphasizing structure of input and output in system. There are the include in this group methodologies such as JAD (Jackson's system development), W/O (Warnier/Orr).
• C. Prescriptive methodology
This methodology usually has been provided by software maker factory. In this methodology including:
o - ISDOS (Information System Design and Optimization System)
o - PLEXSYS
o - PRIDE
o - SDM/70
o - SPECTRUM
o - SRES and SREM, etc.
I. Tool for Developing System
Tools which is used in an methodologies generally in the form of diagram or picture or graph. Besides in form of picture, tools used also there is which in the form of graph or picture like for example data dictionary, structured english, pseudocode, and also forms to note and present data. The tools there are in the form of diagram and chart, example:
1. HIPO diagram
2. Data Flow diagram
3. Structured chart
4. SADT diagram
5. Warnier/Orr diagram
6. Jakson’s diagram
Besides the tools that mention above, there are utilizes that used at all of methodology. The tools as a chart set that grouped by:
• a. Activity charting: to figuring activity, example: chart's substituting, flowchart, etc.
• b. Layout charting: to figuring layout
• c. Personal relationship charting: to figuring person relationship, example: organization chart, working distribution chart
J. Techniques used in developing a system
Techniques used in developing a system, as follows:
• a. Project management techniques, example: CPM and PERT. This techniques used to scheduling project,
• b. Fact finding techniques, techniques to gather and determines data / fact. The techniques that is:
o – Interview, Interview give opportunity to interviewer to motivate customer to answer freely.
o – Observation, Collected data very accurate.
o – Questionnaires, Can bother observation object
o – Sampling, Questionnaire good to resource which is many and spread over.
• c. Cost effectiveness analysis or cost-benefit analysis
• d. Techniques to run meeting
• e. Inspection techniques/walkthrough
K. The differences of being a system analyst and a programmer
A title is just a title and what the people do under those titles can differ from company to company, but in general, a computer programmer translates a design into an actual computer program. A computer analyst, or more commonly called a systems analyst or business analyst or software architect will analyze a company process and design a software package that will improve that process. The systems analysts are usually individuals that bridge the gap between the real world and the programming world. They can speak "both languages" by helping the computer programmers understand the business process and by helping the software users understand the computer programming process. The two titles are similar to the difference between a home builder and an architect.
References:
Hartono, Jogiyanto.2005.Analisis dan Desain Sistem Informasi: Pendekatan Terstruktur, Teori dan Praktik Aplikasi Bisnis. Yogyakarta: Andi.
http://wiki.answers.com/Q/Difference_between_computer_programmer_and_computer_analyst
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