Systems design is the process of defining the architecture, components, modules, interfaces, and data for a system to satisfy specified requirements. Systems design could be seen as the application of systems theory to product development. There is some overlap with the disciplines of systems analysis, systems architecture and systems engineering.
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.
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.
|
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.
