chapter 5 Flashcards
logical model
shows what system must do
physical model
describes how the system will be constructed (how system requirements are implemented
four-model approach
physical model, logical model of current system, logical model of new system, physical model of new system
Data flow diagrams (DFD)
shows how system transfers input data into useful information
- shows how data moves but does not show program - logic/processing steps (what system does not how)
- one page
do not cross lines
process
receives input data and produces output of a different content (rectangle with rounded corners)
data flow
path for data to move from one part of the information system to another (line with arrowhead) (deposit, student grade, order)
data store
data the system stores (useful at some point) (flat rectangle-opened on the right side) (student/prodyct/employees/orders)
entity (terminator)
source
sink
rectangle
- person place or thing
-source= supplies dat
-sink= receives data
context diagram
shows system boundaries and scope
before DFD
leveling, exploring, portioning, decomposing
series of increasingly detailed DFD’s to describe in
data dictionary/ data repository
central storehouse of information about system’s data
data element/ item/field
smaller piece of data that has meaning in info system ( student grade, SSN)
data structures
combined data elements into records (parts inventory: part #, description, supplier code_
Case repository
ensure data is consistent
process description
documents the details of a functional primitive and represents a specific set of processing steps ad business logic
