Chapter 6 Systems Design The design stage in the SDLC Evolution in IS design Evolution in computer architectures The systems approach to design User interface design Data design Procedure design Software design System interface design System control design Quantitative evaluation of design alternatives Information infrastructure design

The Design Stage in the SDLC Fig 6.1: Design Phase Overview

Evolution in IS design 1.Document preparation 2.Organizational problem solving 3.Organizational database 4.Enterprise data model ERDs Data dictionary Object models Two basic types of design Logical Physical

Evolution in Computer Architectures Fig 6.2: The Evolution in Computer Architectures

Evolution in Computer Architectures Mainframe computing Fig 6.3: Mainframe Computing

Evolution in Computer Architectures Client/server computing Fig 6.4: Client/Server Computing

Evolution in Computer Architectures Client/server environments Fig 6.5: Range of Application Partitioning for Web-Based Distributed-Object Computing Web-based distributed object computing

The Systems Approach to Design Identify alternate designs Evaluate alternate designs Select the best

The Systems Approach to Design Identify alternate designs Use system components Fig 6.6: System Design Efforts

The Systems Approach to Design Evaluate alternate designs Fig 6.7: Five Types of Design Performed on Each Configuration of a Sample Module Select the best

User Interface Design Input design Types of input devices Source document design tips  Natural forms completion pattern  Right size fields  Carbon sets  Fit envelopes  Test before printing

User Interface Design Output design Reports Fig 6.8: Types of Reports

User Interface Design Tabular report design tips Use layout forms Complete identifying information Management by exception

User Interface Design Graphical reports Fig 6.10: Sample Graphic Report Formats

User Interface Design Graphical reports design tips Line and bar charts to summarize, show trends Grouped bar to illustrate parts of a whole (versus pie charts) Grouped line and bar to show patterns (versus segmented charts) Use horizontal bars with data values at the ends

Data Design Data modeling approach ERD Data Dictionary Object modeling approach Object class diagram Procedure Design Batch processing Online processing Realtime processing

Procedure Design Batch processing Fig 6.11: Batch Processing

Procedure Design Online processing Fig 6.12: Online Processing Realtime processing

Software Design Strategies Make the client/server decision Adhere to strict naming conventions, path rules, and relative links Limit modules to simple routines Create templates and class libraries Enforce programming principles

Software Design ASTA input/output standards Fig CS 3.5: Standards Input/Output

Software Design ASTA programming standards Fig CS 3.6: Programming Standards

System Interface Design Use Figure 0 DFDs Fig 6.13: The Distribution System

System Control Design Design controls to address risks Risk and control matrices Build controls into each system element

System Control Design Risk matrix Fig 6.14: A Risk Matrix

System Control Design Control Matrix Fig 6.15: A Control Matrix

System Control Design System elements Fig 6.16: Controls Are Designed into System Elements

Quantitative Evaluation of Design Alternatives Fig 6.17: A Quantitative Approach to the Evaluation of a Possible Solution

Information Infrastructure Design AIS Accounting fundamentals Information needs of environmental elements Database design The enterprise systems (support business functions) – MIS, DSS, knowledge-based systems Organization structure Management functions and roles Periodic report design Database design Math modeling Group dynamics