Development system can be a replacement of the old system with a new or refine the old system. Development of the system is very important because it made a number of factors, including:
The old system has problems. problems that arise in the old system can disrupt the way the organization. For example a warehouse system that is still set out to manually enter the goods. But the problems will appear such as: cheating in recording the data warehouse, data errors are not intentional, and employees need a lot of stationery.
Development organization. Development of a larger organization, the interaction and information needs of the area, and volume data processing is also bigger. Therefore, the need to develop a new system to handle it and requires a minimum cost.
Seize the opportunity. Development of information technology more quickly. So if an organization or company using the manual system, the organization can not serve the large demand. So that the company will lose out to compete with other companies engaged in the same field.
There is instruction. The issue of global warming, the government issued a law / instruction to reduce carbon emissions, if not will be subject to sanction. So companies need to develop systems that are environmentally friendly.
Goals developed a new system, expected to be able to handle the problems that exist in the old system, can follow the development of the organization so that it can have the opportunity to reach. In addition, the expected performance of the new system has better performance, the required information can be delivered more quickly, to control cheating faster, effective, efficient and economical. Cheating and so will the problems more quickly by others. For example: system problems such as old warehouses that need so many employees who need the funds there are, the cheating is done, the error in calculation, and the waste can be more quickly.
To develop a system needs to principles of the system are:
system developed for management. So that the system must be able to support the needs of pliers is required by management.
The system developed is a large capital investment. So that should be considered the availability of funds, an alternative system in which you want to develop and the value of investment is equivalent to the benefits obtained.
The systems that need to be developed that educated people
Stages of work and tasks to be done in the development process so that the system needs to establish some of the team to develop.
The process developed should not be massaged so that they can save time. Example: in the procurement of hardware, does not mean system development must be halted until the hardware is coming.
Do not be afraid to cancel the project. If there are problems in its development, the project is not feasible to continue, then the funds will be futile
We must be documentation to guide the development of the system. Documentation can be used for communication between the systems analyst with the system
Waterfall ModelSmall
To medium database software projects are generally broken down into six stages:The relationship of each stage to the others can be roughly described as a waterfall, where the outputs from a specific stage serve as the initial inputs for the following stage. During each stage, additional information is gathered or developed, combined with the inputs, and used to produce the stage deliverables. It is important to note that the additional information is restricted in scope; “new ideas” that would take the project in directions not anticipated by the initial set of high-level requirements are not incorporated into the project. Rather, ideas for new capabilities or features that are out-of-scope are preserved for later consideration. After the project is completed, the Primary Developer Representative (PDR) and Primary End-User Representative (PER), in concert with other customer and development team personnel develop a list of recommendations for enhancement of the current software.
Waterfall Strengths : Easy to understand, easy to use. Provides structure to inexperienced staff, Milestones are well understood, Sets requirements stability, Good for management control (plan, staff, track), Works well when quality is more important than cost or schedule
Waterfall Deficiencies : All requirements must be known upfront, Deliverables created for each phase are considered frozen – inhibits flexibility, Can give a false impression of progress, Does not reflect problem-solving nature of software development – iterations of phases, Integration is one big bang at the end, Little opportunity for customer to preview the system (until it may be too late)
When to use the Waterfall Model : Requirements are very well known, Product definition is stable, technology is understood, Porting an existing product to a new platform, New version of an existing product
Iterative Model
An iterative lifecycle model does not attempt to start with a full specification of requirements. Instead, development begins by specifying and implementing just part of the software, which can then be reviewed in order to identify further requirements. This process is then repeated, producing a new version of the software for each cycle of the model.
A Requirements phase, in which the requirements for the software are gathered and analyzed. Iteration should eventually result in a requirements phase that produces a complete and final specification of requirements. A Design phase, in which a software solution to meet the requirements is designed. This may be a new design, or an extension of an earlier design.An Implementation and Test phase, when the software is coded, integrated and tested.
A Review phase, in which the software is evaluated, the current requirements are reviewed, and changes and additions to requirements proposed.For each cycle of the model, a decision has to be made as to whether the software produced by the cycle will be discarded, or kept as a starting point for the next cycle (sometimes referred to as incremental prototyping). Eventually a point will be reached where the requirements are complete and the software can be delivered, or it becomes impossible to enhance the software as required, and a fresh start has to be made. The iterative lifecycle model can be likened to producing software by successive approximation. Drawing an analogy with mathematical methods that use successive approximation to arrive at a final solution, the benefit of such methods depends on how rapidly they converge on a solution. The key to successful use of an iterative software development lifecycle is rigorous validation of requirements, and verification (including testing) of each version of the software against those requirements within each cycle of the model. The first three phases of the example iterative model is in fact an abbreviated form of a sequential V or waterfall lifecycle model. Each cycle of the model produces software that requires testing at the unit level, for software integration, for system integration and for acceptance. As the software evolves through successive cycles, tests have to be repeated and extended to verify each version of the software.
Spiral Model
The spiral model is an evolutionary software process model that couples the iterative nature of prototyping with the controlled and systematic aspects of the linear sequential model. It provides the potential for rapid development of incremental versions of the software. In the spiral model, software is developed in a series of incremental releases. During early iteration, the incremental release might be a paper model or prototype. During later iterations, increasingly more complete versions of the engineered system are produced.
The goal of the spiral model of the software production process is to provide a framework also called task regions, for designing such as processes, guided by the risk levels in the project at hand. The spiral model may be viewed as a met model, because it can be accommodate any process development model. The main characteristic of the spiral model is that it is cyclic and not linear like the waterfall model. The spiral model allows us to restate the issue of robustness versus correctness. After one cycle of the spiral, unstated requirements are checked as part of the robustness of the application. Each cycle consists of six stages, and each stage is represented by one quadrant of the Cartesian diagram.
Classical Problem-solving approach. Study and understand the problem, its context, and its impact.Define the requirements that must be meet by any solution.Identify candidate solutions that fulfill the requirements, and select the “best” solution.Design and/or implement the chosen solution.Observe and evaluate the solution’s impact, and refine the solution accordingly.
Structured approach. Because there are many problems in classical approach, so we need a better system development approach not only follow the step of system life cycle but also is equipped with several tools and techniques. Piecemeal approachPiecemeal approach is a system development approach that emphasize to an activity or just the application. The selected activity or application is developed without pay the attention from the position in information system or without pay the attention from the organization target comprehensively.
System approach. A series of problem-solving steps that ensure the problem is first understood, alternative solutions are considered, and the selected solution works
Bottom-up approach. A bottom-up approach is piecing together systems to give rise to grander systems, thus making the original systems sub-systems of the emergent system.
Top-down approach. A top-down approach is essentially breaking down a system to gain insight into its compositional sub-systems. Total-system approachTotal-system approach is a comprehensive system development approach. This approach is done hard for the complex system, because will be more difficult to develop.
Modular approach. Modular approach efforts to solve complicate system into several parts or simple modules so that we can understand and develop easily. The system also will be developed according to the time that we have planned, the user can be understood and maintenance the system easier.
Great loop approach. Great loop approach applies whole changing suddenly using modern technology. It is potentially risk because computer technology develops rapidly and next years will be worn out, the investment also expensive and more complicated.
Evolutionary approach. Evolutionary approach required due to size of existing code base. Take best elements from systems and adapt these.
To conduct a development system required a methodology. Methodology is the method, procedures, rules concept used by a science, art or other disciplines. While the method is a way, a systematic technique to grind. Algorithm is the sequence for the problem-solving procedures.
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: HIPO, Stepwise refinement, Information hiding.
B. Data-oriented methodologies Data-oriented is emphasizing on processed data characteristic. This approach can be grouped in two:
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.
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 methodologyThis methodology usually has been provided by software maker factory. In this methodology including:ISDOS (Information System Design and Optimization System), PLEXSYS, PRIDE, SDM/70, SPECTRUM, SRES and SREM, etc.
To perform the steps in accordance with the methodology provided by the development of a structured system, the equipment required in the form of a picture or diagram, or graph and techniques to implement them. Tools in the form of graphs are: HIPO charts, data flow diagrams, structured charts, SADT diagrams, warnier / orr diagrams and charts jakson's. In addition to forming images, tools that can be used nongraphical tools, structured english, forms to record and present data, and charts.
Techniques used to develop the system in all of these methodologies
Engineering project management, the Critical Path Method and Program Evaluation and Review Technique. Technique is used for scheduling the project.
Fact finding techniques, the techniques that can be used to collect data and find the facts in activities to learn the system that exists. Such as interview, observation, sampling and questionaries
Cost-Effectiveness analysis or cost-benefit analysis
Technique for meetings
Technical inspection
System Analyst is to analyze the system (to learn of the problems that arise and determine the needs of the system) to identify a reasoned solution. Programmer who is writing code for an application program based on a design that has been made up by the system analyst. Systems analyst must have a broad knowledge and expertise that is needed.
Systems analyst must have a broad knowledge and expertise that is needed. Here are the skills needed to become a good system analyst.
knowledge and expertise about the data processing techniques, computer technology and computer programming
general business knowledge
Knowledge of quantitative methods
problem-solving skills
communication skills among the personn
elexpertise builds relationships between personnel
