The importance of developing an information system is:
1. problems
Main factor which caused the old system was replaced with the new system because of problems with the old system.
· Irregularity:
Irregularity in the system can cause the old system does not function in accordance with expectations.
For example:
System of a warehousing company, the note has some bugs so that employees can do, such as cheating, cheating to manipulate the data the company's fault or error that is not intentional. Of course this may because the truth of the data is not guaranteed. Therefore, the work of the system will not operate efficiently in
· Growth Organization:
Growth may cause the organization must arrange the new system. The growth of this organization are the information needs of the more knowledgeable, the volume of data increases, the change in the principles of organization and others, causing the old system does not operate effectively.
For example:
a banking company, the company is first to use a SQL database, but the longer the more the customer so that the volume of data to be increase. This requires that the company is changing the banking system into the information-based oracle that can accommodate the new customer data.
2. Opportunity
Information technology is now developing very rapidly. In the current era of competition such as this, information is needed in support of a decision. So companies need a system that can process the information appropriately in accordance with the development of the era.
For example:
Restaurant attract customers by providing hotspot service free to customers who lunch or dinner at the. So that visitors can browse while eating or they can use restaurant to conduct business meetings or other activities.
3. instruction
Change a system can occur because of intruction superiors or the environment outside.
For example:
customers bank who complain to the queue system were established at the time of the transaction. Because of the wide costumer cause a long queue so that many customers tired of standing. Complaints from customers is the bank should change the old system into the new system is using the automated system.
The purpose or goal of developing an information system
There are 3 goals in the development of a system that is:
· Solve the problems that are mainly caused by the old system.
· Seize opportunities in the era of competition, such as now. So companies need to utilize information technology in order to survive and develop.
· Fulfill the instructions given in both in and outside the company environment.
The Organization expectations after implementing the system organization
Performance
performance improvements so that the new system is more effective. Performance can be measured from the throughput and respon time. Throughput means the amount of work that can be done at a certain time. Response time is the average time the pending transaction between the two plus the response time to respond to the job.
For example:
a supermarket to replace the system that excels in sales into the system cashier. So the system is expected cashier will be able to calculate quickly and accurately in accordance with the information required by cashier and customers.
Information
Improving the quality of information generated by the system
for example:
accounting information system that can provide benefits such as company reports and monthly employee salaries, etc. that cannot be done by the old system.
Economy
the new system is expected to increase the benefits or advantages to the company so that it also expected a decline to the cost of going
for example:
a warehouse in a company still using manual system checks in the goods entrance or exit of goods. So that requires a lot of employees on duty, but for now check warehousing system change in the use of information technology systems that can work automatically. So that they can save the labor and production costs can be derived.
Control
Detect and fix errors
for example:
at the supermarket, supermarkets now have been using bar code system for checking and selling goods. So by using this system will be able to detect errors at the time of the transaction with the customer.
Efficiency
Operational efficiency related to how resources are used with the minimum of waste.
Services
Improvement of the services provided by the system.
For example:
the banking system that is able to give even a report that is required in accordance with user preferences
the principles of developing an information system
1.system for management
system is developed for management purposes so that the system must be able to support the needs required by the management
2.system is a large capital investment
information system is identical with the use of technology so that require a large capital to develop it. So every investment capital should consider 2 things, namely:
· All alternatives should be investigated in order to minimize the opportunity cost. Several alternatives should be in the investigation to determine the most profitable alternative.
· Must be the best investment value
said the new investment if the value has. That is the benefit or result great than cost to obtain it from. Cost benefit analysis or cost analysis Effectiveness can be used to determine whether the project is worth investigation or not
3.system developed that require people educated
does not mean the system should be the people who educated about the system but can also be done by providing on the job training to users on how to use the system that is applied.
4. Worked phase to be done in the process of system development
system development cycle generally shows stages work tasks or work to be done. Some development methodology system also provides a more detailed concept work to be done in the process of developing the system.
5. Process development system does not need Ascending
For example:
in the development of the system, the design output is the phase that must be done before the design file. However, this does not mean all of the output should be designed all new design file, but can also be done simultaneously with.
6. Don’t afraid to cancel the project
Cancel the project that are not practical anymore, re-evaluate, adjust the cost and time will be increased, reduce the scope if the cost is not enough to pay for system. After that is expected to manage the risk, to control what may fail later in the project before the process of risk arising
7.documentation there must be guidelines for the development system
documentation created and collected during the process of development of the system can be used for communication between the analyst and the system can be used to encourage the involvement of the system.
The principles of developing an information system
1. Waterfall model
This method proposes an approach to software development and systematic sequential.
Consists of the planning stages of the system (system engineering), analyzes needs, design, writing programs, testing and maintenance the system.
· Requirement or planning systems (systems engineering),
at this stage needs done on the system level, namely the needs of the hardware, software, and databases. Needs of this important collection is done because Software information system that will be built is part of the computer system.
· Analysis of information system needs, at this stage needs to be done collection information system software in the form of input data, processes that occur and the expected output with the interviews and observations, the results from the diagram can be a data flow diagram (DFD) with a data dictionary, relation entity diagram (ERD) or change in the status diagram (STD).
· Design, at this stage to translate the needs analysis in the form of a draft before writing the program in the form of the design of the interface (input and output), the design files or databases and the design procedure (algorithm).
· Implementation, the results on the design changed to the form understood by machines in the form of a programming language. If the detailed design of the program can be done quickly.
Testing, testing process focuses on:
internal logic device to ensure that all statements in the test and has been on an external drive that is functional testing to find errors and to ensure that the limited input that will give the actual value.
· Maintenance
is a system of care that can be used continuously.
The weakness of the waterfall model:
· Iterations often cause new problem
· Client difficulty for all states to explicitly want beginning stage of development.
· The new software will be developed long after the project development starts
Model prototipe (prototyping model)
starting with the collection needs and improvements, the design quickly, forming
prototype, prototype evaluation of the customer, improvement prototype and final product.
· Reaction of the user, beginning with a show prototype information system, and then see the reaction from users when working with the prototype if the features in the system prototype is already in accordance with their needs. Reaction is collected in the observation, interviews and the questionnaire.
· User suggestions, advice is the result of the interaction user with the prototype is shown (user evaluation) which is the input for the improvement, conversion or
'Stop' so that the prototype can meet the needs users better.
· Innovation is the ability of the new system previously did not have at the time the user interacts with the prototype. Innovation prototype if successful will become part of system so results.
· Plan revision, describes the prototype system in the future.
Plan to help identify revision priorities what will be next prototype.
3. Spiral model
This method of analysis of the risk. If the analysis shows there is a risk of uncertainty of demand, the development system can be stopped.
This model is divided into 6 activities are:
1. Communications customer, comunication between developers with customers to determine needs work.
2. Planning, defining the resources, the time-relation information and other projects.
3. Risk analysis, to determine the technical and risk management.
4. Engineering, to build one or more applications that can be represented.
5. Construction and launch, to mengkonstruksi, test, install and provide user support (training).
6. Customer evaluation, to obtain customer feedback based on the assessment of the results of engineering.
Approaches of developing a system
1. Be seen from methodology used
The classical approach versus structured approach
The classical approach
The approach is called classical or traditional approach with the approach is the approach conventional in the development of systems that follow the stages in the life cycle without system provided with the tools and techniques are adequate.
Problems:
· software development will be difficult
· cost of care and maintenance will become more expensive
· possibility on the size of the error system
· success of the system less secure
· problems in the implementation of the system
Structured approach
is an approach to the development of the new system is equipped with several tools and techniques so that the result was successful. Through this approach, complex problem in the organization can be solved and the results from the system will be easy to maintain, flexible, more satisfied users, have a good documentation, on time, according to the budget cost of development, can improve productivity and quality will be better .
2. Be seen from the target to be achieved
the piece approach versus system approach
the piece approach
Emphasizing that the application or on an activity without considering the overall objectives of the organization.
System Approach
emphasizing that the approach in achieving the overall goals and see the system as a whole is unity.
3.Be seen from how to determine the needs of the system
the bottom-up approach versus the top-down
Ride-down approach (bottom-up)
The Approach that starts from the bottom level of the operational level where the transaction is done. Is a discrete approach to classical . Known by the term data-analysis because the pressure is to be data to be processed first, the information generated subsequent to the data.
Top-down approach (top-down)
Starting from the approach that the top-level strategy planning . Is a discrete approach to structured . Also known with the decision-analysis because the pressure is to be the information necessary for decision making by management and the data processed is defined overtake the information required.
4.be seen of how development
The system-comprehensive approach versus modular approach
Comprehensive approach
Develop a system simultaneously and comprehensively
Is a discrete approach to classical
Modular approach
Split the system into the complex parts of a simple
System to be developed on time, easy to understand and kept
Is a discrete approach to structured
5. seen from the technology used
The far-jump approach versus developing approach
The far-jump (great-loop approach)
Develop a system simultaneously using the advanced technology
High-risk and spend a lot of cost
Developing approaches (evolutionary approach)
Applying advanced technology for application-specific applications
Developed for the needs
Cost effective and can follow the development of technology
the meaning of methodology, method and algorithm
System development methodology is the methods, procedures, concepts of work, the rules that will be used as a guide how and what should be done during this development. While the method is a way / technique systematically to grind. Continuity procedures for the settlement of this issue are known by the term algorithm. System development methodology that will be used in this case is a structured approach. Structured approach to introduce the use of tools and techniques to develop a structured system.
three classifications of development methodology
1. Data-oriented
Emphasizes the characteristics of the data processed
Data-flow oriented: modules according to the type of data elements
Data-oriented structure: the structure of input and output
2. Prescriptive
Usually provided by the manufacturer of the software
3. Functional decomposition
Emphasize breaking system subsystem
Example: HIPO, Stepwise refinement, iterative stepwise refinement, information hiding
Tools for developing a system
Shaped graph: HIPO, SADT, Jackson's diagram, and other
· Tools that use the chart:
Charting activity: describes the activities, for example: Gant chart, flowchart, etc.
· Layout charting: describes the layout
· Charting a personal relationship: describes the relationship of personnel, for example: organization charts, work distribution chart
techniques used in developing a system
1. Project management techniques used to project schedule
for example: CPM (Critical Path Method) and pert (Program Evaluation and review technique)
2. Fact-finding techniques
the techniques that can be used to collect data and find the facts in activities to learn the system that exists.
Techniques that can be done are:
· Interview
· Observation
· Questionnaires
· Sampling
3. Technique to analysis of cost / benefit → cost-benefit and cost-Effectiveness analysis
4. Technique to run a meeting
5. Technique to inspection
The differences of being a system Analyst and a programmer
Analyst system: study of the problems and determine the needs of the system to identify solutions
Programmers: write a program code based on the building design is created by the analyst
System analyst duty bridge the knowledge gap that occurs between the user and system programmers
Responsibility of the programmer than the system analyst
Programmers
1. Responsible limited to the programmer of making the computer
2. Knowledge programmers just limited to computer technology, information systems, utilities and languages program is needed
3. Jobs of Programmers are technical and must be precise in making the program instructions
4. Jobs Programmers don’t have relationship with the people, limited to a fellow programmer and systems analysis to prepare a design program.
Analysis system
1. Responsible analyst system not only on making a computer program, but the system overall
2. Knowledge analyst systems must be knowledgeable, not only in computer technology, but also in the field of application in
3. Job of systems analyst in making the program limited to solving the outline.
4. Job of systems analyst relations system involving many people, not limited to fellow analyst system, but also the programmers and system managers
The knowledge a system analyst should posses
Technology, data processing, computer programming and
Business knowledge in general
quantitative methods: regression, linier programming
Problem-solving skills
Communication skills among the personnel
Expertise builds relationships between the personnel
library:
1. analisis dan desain sistem informasi (jogiyanto)
2.rekayasa perangkat lunak (Roger s Pressman)
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