What does a set of DFDs provide?
A logical model that shows what the system does
Does a set of DFDs show how the system does its processes?
no
What are the four basic symbols in a DFD?
process, data flow, data store, external entity
What is the purpose of multiple levels of DFDs?
to show the detail of processes
What are the steps of creating DFDs?
1) Draw a context diagram
2) Draw diagram 0 DFD
3) Draw the lower level diagrams
When do you need to use a data store?
when saving information for use at a later time
What is the conventional numbering process in all levels of DFDs?
...
What is the smallest piece of data that has meaning?
a data element or data item
What are data elements combined into?
records, aka data structures
What are the typical process description tools?
structured English, decision tables, and decision trees
What is structured English?
a subset of standard English that describes logical processes clearly
What are the three guidelines for using structured English?
1. use only the three building blocks of sequence, selection, and iteration
2. use indentation for readability
3. use a limited vocabulary, including standard terms used in the data dictionary and specific words that describe the processing rules
Control structures serve as building blocks for what process?
Modular design
What are the three control structures that are building blocks for the modular design process?
sequence - the completion of steps in a sequential order, one after another
selection - the completion of one of two or more process steps based on the results of a test or condition
iteration - the completion of a process step that is repeated until a sp
What is often the best way to describe a complex set of conditions?
decision tables
What are decision tables?
a logical structure that shows every combination of conditions and outcomes
What does the Four-Model Approach develop?
a physical model of the current system
a logical model of the current system
a logical model of the new system
a physical model of the new system
What are the disadvantages to the Four-Model Approach?
added time and cost
What are data elements documented in?
every data element is documented in the data dictionary
In a DFD, is a 'process' to 'process' data flow valid?
yes (rectangle box <-> rectangle box)
In a DFD, is a 'process' to 'external entity' data flow valid?
yes (rectangle box <-> shaded rectangle box)
In a DFD, is a 'process' to 'data store' data flow valid?
yes (rectangle box <-> small rectangle box)
In a DFD, is an 'external entity' to 'external entity' data flow valid?
no (shaded rectangle <-> shaded rectangle)
In a DFD, is an 'external entity' to 'data store' data flow valid?
no (shaded rectangle <-> small rectangle)
In a DFD, is a 'data store' to 'data store' data flow valid?
no (small rectangle <-> small rectangle)
?In data flow diagrams (DFDs), a process resembles a _____, where the inputs, outputs, and general functions of the process are known, but the underlying details are not shown.
black box
?_____ maintains consistency among data flow diagrams (DFDs) by ensuring that input and output data flows align properly.
Balancing
?A data flow diagram (DFD) shows _____.
how a system transforms input data into useful information
?Since diagram 0 is a(n) _____ version of process 0, it shows considerably more detail than a context diagram.
exploded
?_____ is the process of drawing a series of increasingly detailed data flow diagrams (DFDs), until all functional primitives are identified.
leveling
?Structured English might look familiar to programming students because it resembles _____, which is used in program design.
pseudocode
?Leveling _____.
?uses a series of increasingly detailed data flow diagrams (DFDs) to describe an information system
?The data dictionary usually records and describes a default value, which is the _____.
value for the data element if a value otherwise is not entered for it
?In data and process modeling, a(n) _____ shows what the system must do, regardless of how it will be implemented physically.
logical model
?Among the symbols in the accompanying figure, a _____ receives input data and produces output that has a different content, form, or both.
process
?Among the symbols in the accompanying figure, a _____ is used to represent data that a system stores because one or more processes need to use the data at a later time.
data store
?A _____ documents the details of a functional primitive, which represents a specific set of processing steps and business logic.
process description
A _____ shows how data acts through an information system but does not show program logic or processing steps.
data flow diagram
?Among the symbols in the accompanying figure, a _____ is a path for data to move from one part of the information system to another.
data flow
? In a data flow diagram (DFD), the Gane and Sarson symbol for a data store is a _____.
? flat rectangle that is open on the right side and closed on the left side
?Using _____, an analyst starts with an overall view, which is a context diagram with a single process symbol, and then the analyst creates diagram 0, which shows more detail.
leveling
? In a data dictionary, any name other than the standard data element name is called a(n) _____.
alias
?Balancing _____.
?ensures that the input and output data flows of the parent data flow diagram (DFD) are maintained on the child data flow diagram (DFD)
?In a data dictionary, a(n) _____ is the smallest piece of data that has meaning within an information system.
field
?In a data flow diagram (DFD), the Gane and Sarson symbol for a data flow is a _____.
line with a single or double arrowhead