Information Systems Architecture (ISA)


Conceptual blueprint for organization’s desired information systems structure
Consists of:
 Data (e.g. Enterprise Data Model – simplified ER
Diagram)
What


Processes – data flow diagrams, process decomposition, etc. (DFD- Data Flow Diagram)
Data Network – topology diagram (like Fig 1-9) Where
How
 People – people management using project management tools (Gantt charts, etc.)
Who
 Events and points in time (when processes are performed)
When
 Reasons for events and rules (e.g., decision tables)
Why

 Data flow diagrams (DFDs) are graphical aids that describe an information system
 DFDs represent a logical model that shows what a system does, not how it does it
 Advantages:
 freedom from committing to the technical implementation of the system too early.
 Further understanding the interralatedness of systems and subsystems.
 communicating current system knowledge to users
.

 Data flow diagram symbols
 Four basic symbols
 Process
 Data flow
 Data store
 External entity

External entities
Process
Data flows

Data store

 Functional decomposition
 Iterative process breaking system description into finer and finer detail
 Enterprise data model
 Planning matrixes
 Describe interrelationships between planning objects

Figure 2-2 Example of process decomposition of an order fulfillment function (Pine Valley Furniture)
Decomposition = breaking large tasks into smaller tasks in a hierarchical structure chart

Higher priority business function-to-data entity matrix
Spot missing entity