Lecture 23 CS 507

System Design Designing usable and complete input Designing file or database Designing user interface (input screen as it would be seen by the user) Designing well defined and usable output with flexibility to redefine presentation of outputs in any form.

Designing Usable and Complete Input The input forms should be Accurate Easy to use Consistent Simple Preferably the input forms should be as much near to what is already being used by a business. Primary parameters should also be defined as part of input design e.g. basic information pertaining to various entities suppliers, customers, employees and chart of accounts.

Designing Output Designing should focus on Assuring purposeful output Providing output as defined and required by users Providing appropriate information Assuring distribution of output as per client specified requirements. Minimize throughput time and Query time. Ensuring that output is available in client required mode.

Designing File or Database Accessibility – data is accessible when the user wants to use it. Consistency – data updates in master file will automatically update the data in the whole system. Efficiency -- data is efficiently processed & stored Integrity – correctness of data

Designing User Interface Design should allow the users to access the system in a way that is according to their individual needs. The information should be entered in a logical sequence.

Benefits of Good System Design Better understanding by the developer of the system. System development becomes efficient. Early detection of problems in critical areas, if any. Better quality of reporting formats. Modifications can be made easily in the system. Little maintenance is required in the operations phase.

System Analysis & Design Methods Two approaches are followed for system analysis and design Structured analysis and design – Which includes various tools, such as. Flowcharting Data Flow diagram (DFD) Entity Relationship Diagram (ERD) Object oriented analysis and design

Structured Analysis and Design Structured analysis and design follows a set of good practices and generally accepted standards Proper documentation of the system is made by following the standard rules

Flow Chart "A schematic representation of a sequence of operations, as in a manufacturing process or computer program."

Symbols Arrow Terminator

Symbols Process Decision

Symbols Connectors Predefined Process

Symbols Single Document Off-Page Connector Input / Output

Symbols Input / Output