Chapter 5 - Data and Process Modeling Flashcards
Shows what a system must do, regardless of how it
will be implemented physically
logical model
A model that describes how a system will be constructed.
physical model
A physical model of the current system, a logical model of the current system, a logical model of the new system, and a physical model of the new system are all developed.
four-model approach
A popular symbol set used in DFDs. Processes, data flows, data stores, and external entities all have a unique symbol.
Gane and Sarson
A type of symbol set that is used in DFDs. Processes, data flows, data stores, and external entities each have a unique symbol in the _______ symbol set.
Yourdon
Procedure or task that users, managers, and IT staff members perform. Also, the logical rules of a system that are applied to transform data into meaningful information. In data flow diagrams, a _______ receives input data and produces output that has a different content, form, or both.
process
Rules to determine how a system handles data and produces useful information, reflecting the operational requirements of the business. Examples include adding the proper amount of sales tax to invoices, calculating customer balances and finance charges, and determining whether a customer is eligible for a volume-based discount.
business logic / business rules
A metaphor for a process or an action that produces results in a non-transparent or non-observable manner. In data flow diagrams, a process appears as a _______ where the inputs, outputs, and general function of the process are known, but the underlying details are not shown.
black box
A path for data to move from one part of the information system to another.
data flow
An unexplained generation of data or information. With respect to DFDs, processes cannot _________________ data flows—they must have an input to have an output.
Spontaneous generation
A process that has no output
Black hole
A process with an input obviously insufficient to generate the shown output.
Gray hole
A person, a place, a thing, or an event for which data is collected and maintained. For example, an online sales system may include entities named CUSTOMER, ORDER, PRODUCT, and SUPPLIER.
entity
A DFD symbol that indicates a data origin or final destination. Also called an external entity.
terminators
An external entity that supplies data to an information system.
source
An external entity that receives data from an information system.
sink
A top-level view of an information system that shows the boundaries and scope.
context diagram
In a DFD, ________ represents the entire information system but does not show the internal workings.
process 0