Information Systems Analysis and Design [part II]
Posted by: dwixmilanisti on: March 6, 2009
Existence of problems that appear in system old ones. Problems of arising out such of
a. Existence of Problems (Problems)
Disability of old system in solving problem and didn’t work as the expected until information system needed..
b. Annoyance in Growth’s system of Organization
The big need and request about information, the increase of data tabulation volume and the change of new accounting principle causes old system not capable and effective anymore, so we need to make the information system.
c. For reach the opportunities ( opportunities )
d. Existence of instructions ( directives)
The Compilation of new system can also happened caused by instruction – instruction from the leader or from outside organization, for example regulation of government.
There are the purposes of development of information system.
a. Solving problems
By the information system, problem of disability of old system in solving problem will be finished..
b. Reach for opportunities
c. Fulfill the instruction that given
There are the expectations of organization after executing the information system
a. Performance ( performance)
Measured to use and throughput of response time. By the performance information system from a organization will mount progressively and more effective.
b. Information ( information)
increase the quality of information.
By the information system, presentation of message or information from an organization will progressively mount
c. Economy ( economic)
increase the benefit of vs decreasing cost. By the information system, make-up of benefits will mount progressively . And expense which needed can be depressed or lessened.
d. Control ( operation)
Detecting and improve the mistake.
e. Efficiency ( efficiency)
Efficient of operational.
f. Services ( service)
Increase the service of system.
There are some principles of system development of information
a. System for the management
b. System is a big investment
Investigation of all alternative ( minimizing missing cost opportunity). Best investigation have to be valuable : analysis cost-benefit & analysis cost-effectivines
b. System need educated people
The system need people that professional on each department, not ought to have the high education, the important think that people must really professional on the department that they handle.
c. Step work -> System cycle life development
d. System development do not have to numbering
e. Don’t fear to cancel project
f. System documentation
Three cycle live development of system are
a. Model of Waterfall
The waterfall model is a popular version of the systems development life cycle model for software engineering. Often considered the classic approach to the systems development life cycle, the waterfall model describes a development method that is linear and sequential. Waterfall development has distinct goals for each phase of development. Imagine a waterfall on the cliff of a steep mountain. Once the water has flowed over the edge of the cliff and has begun its journey down the side of the mountain, it cannot turn back. It is the same with waterfall development. Once a phase of development is completed, the development proceeds to the next phase and there is no turning back
Initiation/Planning
To generate a high-level view of the intended project and determine the goals of the project. The feasibility study is sometimes used to present the project to upper management in an attempt to gain funding. Projects are typically evaluated in three areas of feasibility: economical, operational, and technical. Furthermore, it is also used as a reference to keep the project on track and to evaluate the progress of the MIS team.[6] The MIS is also a complement of those phases. This phase is also called the analysis phase.
Requirements Gatherings And Analysis
The goal of systems analysis is to determine where the problem is in attempt to fix the system. This step involves breaking down the system in different pieces and drawing diagrams to analyze the situation. Analysts project goals, breaking down functions that need to be created, and attempt to engage users so that definite requirements can be defined.
In systems 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.
Modular and subsystem programming code will be accomplished during this stage. Unit testing and module testing are done in this stage by the developers. This stage is intermingled with the next in that individual modules will need testing before integration to the main project. Planning in software life cycle involves setting goals, defining targets, establishing schedules, and estimating budgets for an entire software project
The code is tested at various levels in software testing. Unit, system and user acceptance testing are often performed. This is a grey area as many different opinions exist as to what the stages of testing are and how much if any iteration occurs. Iteration is not generally part of the waterfall model, but usually some occurs at this stage.
Types of testing:
Data set testing
The deployment of the system includes changes and enhancements before the decommissioning or sunset of the system. Maintaining the system is an important aspect of SDLC. As key personnel change positions in the organization, new changes will be implemented, which will require system updates.
The advantage of waterfall development is that it allows for departmentalization and managerial control. A schedule can be set with deadlines for each stage of development and a product can proceed through the development process like a car in a carwash, and theoretically, be delivered on time. Development moves from concept, through design, implementation, testing, installation, troubleshooting, and ends up at operation and maintenance. Each phase of development proceeds in strict order, without any overlapping or iterative steps.
b. Model Iterative
In computer programming, iterative is used to describe a situation in which a sequence of instructions can be executed multiple times. One pass through the sequence is called an iteration. If the sequence of instructions is executed repeatedly, it is called a loop, and we say that the computer iterates through the loop.
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-users; insights gained from the critique of an 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.
The challenge in iterative development is to make sure all the iterations are compatible. As each new iteration is approved, developers may employ a technique known as backwards engineering, which is a systematic review and check procedure to make sure each new iteration is compatible with previous ones. The advantage of using iterative development is that the end-user is involved in the development process. Instead of waiting until the application is a final product, when it may not be possible to make changes easily, problems are identified and solved at each stage of development. Iterative development is sometimes called circular or evolutionary development.
c. Model Spiral
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.
There are the approve of development a system.
a. Classic approach vs approach of structure
Classic approach represent opponent from approach of structure.
Classic approach
Classic approach can also traditional approach or conventional approach.
a) Steps in SDLC
b) Do not involve consumer, for emphasizing the system analyst
c) Problems: difficult development, expense of costly treatment, possibility of big mistake, efficacy less well guaranted, applying internal issue
Approach of structure
a) Consumer involve from early to determine the requirement of system
b) Using tools-tools like data of flow diagram
b. Approach of rasher of vs approach of system
Approach of rasher
a) Emphasizing at an activity or application
b) Heedless of entirety target
Approach of system
a) See system as one intact unity
b) Emphasizing at goal achievement as a whole
c. Approach of bottom-up vs approach of top-down
Approach of bottom-up
a) Started from level under that is operational
b) Representing classic approach marking
c) Recognized with term of data-analysis
Approach of top-down
a) Started from up level that is planning of strategy
b) Representing marking approach of restructure
c) Recognized also with decision-analysis
d. Approach of vs whole system vs approach of modular
Approach of whole system
a) Developing system at a time and totally
b) Representing classic approach marking
Approach of modular
a) Breaking complicated system become the parts of simple
b) Developed system become timely, easy to be comprehended and looked after
c) Representing marking approach of structure
e. Approach of great loop approach vs expand
Approach of ( approach great-loop )
a) Developing system at a time use sophisticated technology
b) High risk and finish many expense
Approach expand ( approach evolutionary)
a) Applying sophisticated technology for certain applications
b) Developed to follow requirement
c) Cost effective and can keep abreast of technology
There are the congeniality of methodology, method, and algorithm
a. Methodologies is the Methods which is used in science. Methodologies is unity of method – method, procedure – procedure, concept – conception work, order – postulate and order – postulate used an science, artistic or the other discipline.
b. Method is a way of systematic to do something.
c. Algorithm is procedure sequence to solve a problem
There are the Clarification of three classification of methodology development of system
a. Decomposition Functional
Emphasizing resolving of system become sub system
Example : HIPO, Stepwise Refinement, refinement stepwise iterative, hiding information
b. Data-Oriented
Emphasizing at processed data characteristic
a) Oriented Data-flow: modules according to data element type
b) Oriented Data-structure: input structure and of output
c. Prescriptive
usually provided by factory maker of software
There are the appliance – appliance used to develop a system
a. In form of graph: HIPO, SADT, Jackson’s Diagram, and others
b. Appliance using schema
a) Charting Activity: depicting activity, example of: Chart Gant, flowchart, etc
b) Charting Layout: depicting the place of system
c) Relationship charting Personal: depicting personnel , example : chart organization, chart distribution working
There are the technique – used technique in developing a system
a. Management technique of project for schedule of project , example : CPM and of PERT
b. Technique find fact to collect and determine data / fact 1. Interview 2. Observation
c. Technique analyse expense / benefit of cost-benefit and cost-effectiveness analysis
d. Technique to do the meeting
e. Inspection technique
The Difference of system’s analyst and a programmer
a. System analyst: studying problems and determine requirement of system to identify resolving
b. Programmer: writing program code pursuant the design made by analyst
System analyst undertake to link difference of knowledge that happened between system’s analyst and system of programmer
There are the Knowledge that used an analyst system to influence a system
a. Data-Processing technology, and computer of programming
b. Knowledge of business in general
c. Quantitative method: regretion, linear programming, etc
d. Skill of trouble-shooting
e. Skill of communications between personnel
f. Skill to construct relation between personnel
