Detailed System Design

Conceptual design in itself is not the end of the design process, rather it servers as a basis for the detailed MIS design. The performance requirements specified by the conceptual design become inputs to the detailed design phase, in which these are further refined, detailed and finalized to be called the system specifications.

Thus, the main objective of the detailed system design is to prepare a blue print of a system that meets the goals of the conceptual system design requirements. Detailed system design involves the following phases.

    Project planning and control.
    Involve the user
    Define the detailed sub-system.
    Input/Output design.
    Feedback form the user
    Database design.
    Procedure design.
    Design Documentation

1) Project planning and control

In order to ensure an effective and efficient design of an MIS, it is very important that a detailed design process should in itself be considered a complete project. Therefore, the first step in the detailed design is planning and controlling, so that standards may be established and a proper follow-up is made. Some of the main points, which are important in planning and control of a detailed design, are given below.

Project planning

1.      Formulate the project objectives.
2.      Define the project tasks.
3.      Prepare a network diagram of all events and activities so as to specify sequential and parallel events.
4.      Schedule the work as per the requirements of the user.
5.      Prepare a budget for the project.

Project control

    Get a feedback of the actual performance of the project with respect to time, cost and work of the project and compare it with schedules, budgets and technical plans.
    Take corrective action where required so as to maintain control.

2) Involve the user

System designers must inform the user regarding the new information system being developed and gain their support and acceptance. In this phase, users are assured that changes will benefit them or that they will not be at disadvantage because of the new system.

3) Detailed sub system definition

In detailed system design, every system needs to be broken down to ascertain all activities required and their respective inputs and outputs. In some of the cases, sub systems are broadly defined in the conceptual design phase, but at this stage they are specifically defined to work out every detail concerning the sub-system. Decomposition of the system to operational activities in general is carried out as follows.

System

               Sub System

                       Functional component

                               Task

                                    Sub Task

                                            Operation element
 

4) Output/Input Design

Having defined the subsystem well, by way of flow diagrams and a through discussion with the users of MIS, the system designers now define the specifications of outputs and inputs for each sub-system, in more detail. These specifications will later be used by programmers to develop programs to actually produce the output/input.

5) Feedback from the user

Having specifically defined sub-system, output and inputs, the designers once again involve the user to get feedback. This step will increase the acceptance of the MIS being designed. The system analyst should demonstrate the proposed MIS to the users of the system/sub-system. This step will also reassure the top management of the user organization that the detailed design project is processing as per plans.

1)      Database design 

A database is an orderly arrangement of all the records related to each other. It servers as a data resource for the MIS of an organization. To have optimum performance, storage and fast retrieval of data, database design is an important phase in the detailed design of a system. For designing a database, the designer should keep the following points in mind.

    Identify all data tables and record types.
    Identify fields for each table, the key fields for each table and relations between various tables.
    Determine the data type and width for each field of the tables.
    Normalize the data tables.
    Properly document data dictionary.

7) Procedure design

Procedures are the rules, standards or methods designed to increase the effectiveness of the information system. The procedures detail about the tasks to be performed in using the system. They serve as the ready recovers for the designers as well as for the users. Sometimes they perform the task of a supervisor over operators. There are a wide variety of procedures, which include:

    Data entry procedures.
    Run time procedures.
    Error handling procedures.
    Security and back up procedures.
    Software documenting procedures.

In designing procedures, designers should:

    Understand the purpose and quality standards of each procedures
    Develop a step-by-step direction for each procedure, and
    Document all the procedures.

8) Design Documentation 

Detailed design starts with the performance specifications given by the conceptual design and ends with a set of design specifications for the construction of MIS. The outputs from the detailed design, i.e. design specifications, are handed over to the programmers for writing codes to translate system specifications into a physical MIS. Therefore, the system analyst should very carefully document the detailed design. In fact, design documents should consist of comprehensive details of all the design phases. Design documentation of detailed design report, generally, consists of

    System objectives,
    Design constraints,
    Inputs/outputs,
    Data files,
    Procedures (manuals)
    Proposed system (a summery and detailed flow charts),
    Input/Output specifications,
    Program specifications,
    Database specifications,
    Cost of installation and implementation, and
    System test conditions.