the importance of developing an information system
Development of system mean: to compile a new system to replace system old ones, or improve the old system. Something causing the system requires to be improved are:
· Existence of Problems (problems)
· Annoyance in Growth’s system Of Organization
· To Reach for opportunities (opportunities)
· Existence of instructions (directives)
the purpose or goal of developing an information system
To solving the problems
Reach for opportunities
Fulfilling given instruction
organization’s expectations after implementing an information system are :
· Performance: performance of system developed cans more mounting so that become more effective. This can be measured with throughput (amount of work of which is it can done in one moment) and its response.
· Information: make-up of quality to presented information.
· Economy: make-up of advantage or benefit or decreasing cost that happened.
· Control: make-up of operation to detect and improve mistake and also insincerity that would be happened.
· Efficiency: make-up of to operation efficiencies. Efficiencies relate to how the resource used by reckoning lowest expenditure.
· Services: make-up of to service given by system
the principles of developing an information system
· System which is developed is management
· System which is developed is big capital investment
· developed System need one who is have education
· Step of work and duty which must be conduct in course of developing system
· The process to developing system didn’t have to be successive
· Don’t fear about to canceling a project
· Documentation existence for guide in system development.
three system development life cycle models
Systems Development Life Cycle
The Systems Development Life Cycle (SDLC) is a conceptual model which used in project management that describes the stages involved in an information system development project from an initial feasibility study through maintenance of the completed application. Various SDLC methodologies have been developed to guide the processes involved including the waterfall model (the original SDLC method), iterative model and the spiral model.
1. Waterfall model
The image below is the classic Waterfall model methodology, which is the first SDLC method and describes the various phases involved in development.
Briefly on different Phases:
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 (how the individual programs are going to work), interface design (what are the interfaces going to look like) and data design (what data will be required).
Design
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
In this phase the designs would be translated into code. Computer programs are write it using a conventional programming language or an application generator
Testing
In this phase the system will be tested until its work . Normally programs are written as a series of individual modules, these subjects to separate and detailed test.
Maintenance
Inevitably the system will need maintenance. Software will definitely undergo change once it is delivered to the customer.the 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 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-user 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 spiral model, also known as the spiral lifecycle model, is a systems development lifecycle (SDLC) model used in information technology (IT). This model of development combines the features of the prototyping model and the waterfall model. The spiral model is favored for large, expensive, and complicated projects.
The steps in the spiral model can be generalized as follows:
1. 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.
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. 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.
5. At the customer’s option, the entire project can be aborted if the risk is deemed too great. Risk factors might involve development cost overruns, operating-cost miscalculation, or any other factor that could, in the customer’s judgment, result in a less-than-satisfactory final product.
6. 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.
7. The preceding steps are iterated until the customer is satisfied that the refined prototype represents the final product desired.
8. The final system is constructed, based on the refined 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.
Approaches of developing a system
There are several approach to developing a system, that is:
· Classic approach vs. structured approach
Classic approach is approach inside of developing a system that follow stages at system life cycle without supplied with tools and techniques.
Troubleshoots which can arise from this approach, such as:
1. Difficult development.
Classic approach less give tools and techniques insides develop system and finally software development process becoming not directional and difficult to be done by programmer.
2. Treatment cost or system maintenance will be more expensive.
The expensive treatment cost at classic approach caused system documentation that developed less complete and less structured.
3. Possibility of big error.
This approach doesn’t prepare to manner systems analysis to do system testing, so that system errors possibility will be bigger.
4. System achievement less well guaranteed.
Because classic approach less involve system user in system development, so system user needs are less matching with the one which desirable and as finally system that applied less success.
5. Applying internal issue.
User will be startled and unaccustomed with new system suddenly introduced.
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. In this approach, consumer involve from early to determine requirement of system and using tools like data of flow diagram
· Piecemeal approach vs. system approach
Piecemeal approach is system approach development that emphasized at one particular activity or certain application. This approach don’t heed overall target.
System approach pays information system as integration unitary to each activity or the application. This approach also emphasized in overall goal achievement from organization, not only in that information target.
· Approach of bottom-up vs. approach of up-down
Bottom-Up Approach is begin from level under organization, that is from formulation requirements to handle transaction and climb level on with formulate information need based on transaction. Bottom-up approach is used in systems analysis steps, because of the pressure is data that be cultivated before, information that be produced will follow the data. Up-Down Approach on the contrary with bottom-up approach, this approach is begin from level up organization, that is begun with define target and organization policy. Step furthermore from this approach information need analysis. After information is determined, so process goes to transaction processing, that is determination output, input, data base, operating procedure and control. This approach be feature from structured approach. Top-down approach when used in systems analysis stage called also with term decision analysis, because that be pressure information that wanted for decision making by management beforehand, then data necessary cultivated to defined to follow information that wanted.
· Total-system approach vs. modular approach
Total-system approach to be approach develops system together according to comprehensive. This approach less synchronized for complex system, because will be difficult be developed. This approach be 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 be feature structured approaches.
· great-loop approach vs. evolutionary approach
Great-loop approach applies change comprehensive according to together use sophisticated technology. This change contains many risks, because computer technology so great-loop. This approach also too expensive, because need investment at the same moment for all technology that used and difficult to developed because too complex. Evolutionary approach apply sophisticated technology just for applications that need that moment and then be developed for periods next based on technology development. This approach causes investment not too expensive and can follow fast technology development.
Meaning of methodology, method and algorithm
Methodologies: unity of method, procedure, conception work, postulate or the order which is used in a science, artistic and or discipline. Method: systematic technique to do something. Algorithm: sequential Procedure to solve a problem
The three classifications of development methodology
There are three classifications of developing a system, they are :
• Functional decomposition
Functional decomposition is emphasizing system which resolving becomes subsystem. For examples :HIPO, Stepwise refinement.
• Data-oriented
Data-oriented is emphasizing on processed data characteristic.
• Flow oriented data: types appropriate modules data elements
• Structure oriented data: input structure and output
• Prescriptive
Usually provided by software maker factory.
Tools for developing a system
Get graph form: HIPO, SADT, Jackson’s diagrams, etc.
Tool that utilizes to design are:
· Activity charting: figuring activity, example: chart’s substituting, flowchart, etc.
· Layout charting: figuring layout
· Personal relationship charting: figuring person relationship, example: organization chart, working distribution chart
Techniques used in developing a system
There are techniques which used in order to developing a system, they are:
· analysis’s tech cost / benefit à cost benefit and cost effectiveness analysis
· Tech finds fact à this technique used to gather and determines data / fact
· Interview
· Observation
· Project management techniques à this technique used to scheduling project, for example: CPM and PERT
· Going tech shuts close
· Inspection tech
the differences of being a system analyst and a programmer and also mention what are the knowledge a system analyst should posses
Who Analysis System And Programmer are ?
The Analysis system is people who study about analyzing system and identifying problems and determine system which user needs
Programmer is people who write program’s code to create an application which it based on has planned to get up by system analyst.
Function and or task from a analyst system that is as mediator or liaison between system user with programmer. Analyst system must realize right second knowledge differ about the computer technology to can communicate with programmer and knowledge about application that be developed so that can communicate with system user.
Knowledge And Skill That must Need by System Analyst
Found several vast eruditions and skill that must has by a system analyst, that is:
1. Knowledge and skill about data processing technique, computer technology and computer programming.
Technical skill that must has belonged skill in using tool and technique for application software development with skill in using computer.
Technical knowledge that must be has by system analyst are erudition about hardware, data communication technology, computer languages, os, utilities, and another.
2. Knowledge about business for general.
This knowledge be wanted so that system analyst can communicate with system user
3. Skill builds connection delivers staff.
Human is critical factor insides system and one of human character with another differ, so that need a skill to build connection delivers staff
4. Trouble-shooting skill.
System analyst must has ability to put complex troubleshoots which is faced by business, divide problem into parts, analyze and then must can returning composed to be a system can overcome troubleshoots.
5. Knowledge about quantitative method.
System analyst use many quantitative methods in build an application models, like dynamic programming, regression, network, decision tree, trend, simulation and other like it.
6. Communication skill delivers staff.
System analyst must has an ability to hold communication either through tongue or article. This skill is need in interview, presentation, meeting and report maker.
