Information Systems Architecture(ISA)

• Conceptual blueprint for organization’s desired information systems structure

• Consists of (6Ws):– Processes–data flow diagrams, process

decomposition, etc. (DFD- Data Flow Diagram)– Data (e.g. Enterprise Data Model–ER Diagram)– Data Network–topology diagram (like Fig 1-9)– People–people management using project

management tools (Gantt charts, etc.)– Events and points in time (when processes are

performed. Use case diagram)– Reasons for events and rules (e.g., decision tables)

WhatWhat

HowHow

WhereWhere

WhoWho

WhenWhen

WhyWhy

Data Flow Diagrams• Data flow diagrams (DFDs) are

graphical aids that describe an information system

• Advantages:– freedom from committing to the technical

implementation of the system too early.– Further understanding the interrelatedness

of systems and subsystems.– communicating current system knowledge

to users .

Data Flow Diagrams

• Data flow diagram symbols– Four basic symbols

• Process

• Data flow

• Data store

• External entity

Process

Data flowsExternal entities

Data store

Data Dictionary

Datastructure

ProgramModules

Datastructure

Datastructure

Develop Enterprise Model

• Functional decomposition– Iterative process breaking system description into finer and finer detail

• Enterprise data model • Planning matrixes

– Describe interrelationships between planning objects

Example business function-to-data entity matrix (Fig. 2-3)Higher

priority

Spot missing entity