How Do I Become an Information Systems Analyst?

Information system design, also known as the physical design of the information system, is based on the analysis of the system. It transforms the logical model that reflects the needs of users in the system analysis phase into a physical model of the information system that can be implemented. problem. At this stage, the structure of the new system should be determined in detail according to economic, technical, and operating environment conditions, and the necessary technical solutions for the implementation of the information system should be provided.

Information system design

1. Tasks of system design ^[1]

The task of information system design is to transform the logical model of the information system into a physical model. Information system design should follow the following principles. ^[2]

The system design plan should be evaluated, and the plan that fails to meet the design standards should be sent back for redo, not because the iterative development is adopted, and the lack of design and confusion can be condoned. Bringing bad design results to the next development phase will greatly extend the construction period, because design defects found during the system implementation phase are often after doing a lot of useless work. Although refactoring techniques can help fix problems at the design stage, large-scale refactoring is a costly and daunting move for both novice and experienced developers. Poor functional design is one of the main reasons for large-scale refactoring, and large-scale refactoring is very detrimental to maintaining the synchronization of design documents and program code framework, and may even lead to the complete obsolescence of previous design documents. The result of rigorous review of the functional design, that is, "the knife is not cut by mistake". ^[3]

The evaluation criteria of functional design and design quality are closely related, mainly including the following aspects.

(1) Correctness

It must be ensured that all functions and tasks proposed in the analysis phase are correctly designed, which is the minimum requirement for the design results. The correctness of the design is mainly determined by experienced analysts. The focus of the evaluation is whether the business logic in the original analysis stage can still be correctly executed after the system is decomposed in the design stage. Correctness assessment is often not done at one time. In the process of generating and writing source code and running tests, you can always find defects or even errors in the design. The correctness requirement in functional design is to strive for design results (design framework) at a higher level without major errors, otherwise the subsequent iterations will be very difficult.

(Two) integrity

The integrity requirements of the design phase mainly include two aspects: structural integrity and component integrity. Structural integrity means that all aspects of the entire system must be designed without omissions; component integrity means that each component should have a clear meaning and clear responsibilities. Strict adherence to the principles of encapsulation in object-oriented design can avoid excessive exposure of details, which in turn contributes to the realization of completeness.

(Three) reliability

In the design, standardized design tools (such as UML design tools) should be used, and various common or successfully applied design patterns should be used as far as possible to avoid the use of irregular or even weird design solutions. Components, reducing repetitive development. Only proven ones are reliable.

(IV) Reasonable design

Classes are the basis of object-oriented system development, so special attention needs to be paid to system design work. The proper construction of a class design involves whether the class is clearly defined, whether the class-to-class relationship is clear, and whether the class granularity is appropriate. The so-called "reasonable" does not have an absolute standard. In most cases, it is judged by the analysis and designer's own development experience.

(V) Rigorous interface definition

Interface design is a very important task in object-oriented design, and it is also one of the most difficult tasks. The analysis phase basically does not consider physical interface issues, and leaves this work to the design phase. The definition of the interface should be based on the principle of lack of overwhelmingness, and interfaces that can be private should never be made public. The naming of the interface must be elaborated repeatedly, which must be accurate and as simple as possible; at the same time, it is necessary to pay attention to the specific parameter selection of the interface method.

(VI) Complete chart documents

Designing diagrams and documentation is one of the best ways to help other developers understand the system. It should be as complete and historical as possible to facilitate backtracking. When evaluating design schemes, for some important or large-scale designs, you can assign different weights to each evaluation index according to the specific requirements and characteristics of the actual project, and then the experienced designers and analysts will score the schemes. ; For general or partial design, the designer can determine it based on experience.