Ch 7 - Structuring Sys Reqs - Process Modeling Flashcards
What is Process Modeling?
Graphically represents the processes that capture, manipulate, store, & distribute data b/w system & its environment & among system components
What is DFD/
Data-flow Diagrams - illustrates the movement of data b/w external entities & the processes and data stores within a system (models how data flows or moves through existing/proposed system)
Data Store in DFD
Depicts data at rest. Is a holding area for data, named using a noun, & only processes may connect to it.
Process in DFD
Depicts work or actions performed on data so incoming data flows are transformed, stored or distributed into outgoing data flows.
Source/Sink in DFD
Depicts origin/destination of data. Represents system boundary, not all of whose attributes are of interest
Data Flow in DFD
Depicts data that’s in motion & moving as a unit from one place in the system to another. Connects everything together.
DFD Levels
Context Diagram
Level 0 diagram (system diagram)
Level 1 diagram
Leven n diagram
Primitive diagram
What is a Context Diagram?
Defines the scope of a system by identifying the system boundary. Is one process (0) & represents the entire system. All sources/sinks 7 data flows
What is a Level-0 Diagram?
A data-flow diagram that represents a system’s major proecsses, data flows, & data stores at a high level. Describes overall processing for the system
What is Functional Decomposition in a DFD sequence?
Iterative process of breaking the description of a system into finer and finer detail to create a set of charts in which one process on a given chart is explained in greater detail on another chart.
How to Balance DFDs
When decomposing a DFD, you need to conserve inputs to and outputs from a process at the next level of decomposition.
What are the three parts of modeling logic with decision tables?
- Condition stubs
- Action stubs
- Rules
