What is a DATA DICTIONARY?
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Transcript of What is a DATA DICTIONARY?
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The Data Dictionary
a quasi-formal grammar for describing the content of data that the software will process and create a notation for describing control data and the values that control data can take, e.g., "on," or "off" a repository that also contains "where-used" / "how used" information a notation that can be represented manually, but is best developed using CASE tools
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Building a Data Dictionary
Name: Aliases: Where used: How used: Description: Format:
the primary name of the composite data item other names for the data item data transforms (processes) that use the composite data item the role of the data item (input, output, temporary storage, etc. a notation for representing content (presented on next slide) specific information about data types, pre-set values (if known)
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Data Dictionary Notation
Notation
=
+
[ ]
{ }
( ... )
* ... text ...*
n
Meaning
is composed of
and
either-or
n repetitions of
optional data
delimits a comment
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Data Dictionary Example
telephone numberintegrated
office phone system
Name: Aliases: Where/How us ed: Description: Format:
telephone number phone number, number read-phone-number (input) display-phone-number (output) analyze-long-distance-calls (input) telephone no. = [ local extension | outside no. | 0 ]
outside no. = 9 + [ service code | domestic no. ]
service code = [ 211 | 411 | 611 | 911 ]
domestic no. = ( ( 0 ) + area code ) + local number
area code = *three numeral designator*
Build the requirements dictionary:
alphanumeric data
system output
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Control Flow ModelCFD is a diagram to describe the control flow of a
business process, or program.
Begin by stripping all the data flow arrows from the DFD
Events (solid arrows) and control items (dashed arrows) are added to the diagram
Add a window to the CSPEC (contains and STD that is a sequential specification of the behavior) for each
bubble.
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CFD for Safe Home
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State Transition Diagram
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Process Activation Table