THE
DATA DICTIONARY
The
data dictionary is a specialized application of the kinds of
dictionaries used as references in everyday life. The data dictionary
is a reference work of data about data (that is, metadata),
one that is compiled by systems analysts to guide them through
analysis and design.
Need
for Understanding the Data Dictionary
Understanding
the process of compiling a data dictionary can aid the systems
analyst in conceptualizing the system and how it works.
In
addition to providing documentation and eliminating redundancy, the
data dictionary may
be
used to:
1.
Validate
the data flow diagram for completeness and accuracy.
2.
Provide
a starting point for developing screens and reports.
3.
Determine
the contents of data stored in files.
4.
Develop
the logic for data flow diagram processes.
5.
Create
XML (extensible markup language).
THE
DATA REPOSITORY
the
data dictionary contains information about data and procedures, a
larger collection
of
project information is called a repository. The repository may
contain the following :
1.
Information
about the data maintained by the system, including data flows, data
stores,
record
structures, elements, entities, and messages.
2.
Procedural
logic and use cases.
3.
Screen
and report design.
4.
Data
relationships, such as how one data structure is linked to another.
5.
Project
requirements and final system deliverables.
6.
Project
management information, such as delivery schedules, achievements,
issues that
need
resolving, and project users.
The
data dictionary is created by examining and describing the contents
of the data flows, data stores, and processes.
Defining
the Data Flows
The
information captured for each data flow may be summarized using a
form containing the following information:
1.
ID,
an optional identification number. Sometimes the ID is coded using a
scheme to
identify
the system and the application in the system.
2.
A
unique descriptive name for this data flow. This name is the text
that should appear on the diagram and be referenced in all
descriptions using the data flow.
3.
A
general description of the data flow.
4.
The
source of the data flow. The source could be an external entity, a
process, or a data flow coming from a data store.
5.
The
destination of the data flow (same items listed under the source).
6.
An
indication of whether the data flow is a record entering or leaving a
file or a record containing a report, form, or screen. If the data
flow contains data that are used between processes, it is designated
as internal.
7.
The
name of the data structure describing the elements found in this data
flow. For a
simple
data flow, it could be one or several elements.
8.
The
volume per unit of time. The data could be records per day or any
other unit of time.
9.
An
area for further comments and notations about the data flow.
Analyzing
Input and Output
An
important step in creating the data dictionary is to identify and
categorize system input and output data flow. Input and output
analysis forms contain the following commonly included fields:
1.
A
descriptive name for the input or output. If the data flow is on a
logical diagram, the name should identify what the data are (for
example, CUSTOMER INFORMATION). If the analyst is working on the
physical design or if the user has explicitly stated the nature of
the input or output, however, the name should include that
information regarding the format. Examples are CUSTOMER BILLING
STATEMENT and CUSTOMER DETAILS INQUIRY.
2.
The
user contact responsible for further details clarification, design
feedback, and final approval.
3.
Whether
the data is input or output.
4.
The
format of the data flow. In the logical design stage, the format may
be undetermined.
5.
Elements
indicating the sequence of the data on a report or screen (perhaps in
columns).
6.
A
list of elements, including their names, lengths, and whether they
are base or derived, and their editing criteria.
Using
Data Dictionaries to Create XML
Extensible
markup language (XML) is a language that can be used to exchange data
between
businesses
or between systems within a business. It is similar to HTML, the
markup language used to create Web pages, but is more powerful. HTML
is concerned primarily with formatting a document; XML addresses the
problem of sharing data when users have different computer systems
and software or different database management systems.
Penulis: Yusia /Kaleb
Referensi:
[1] Kendall, K.E., Kendall, J.E., Systems Analysis and Design. Prentice Hall. 2011. New Jersey, USA.
Referensi:
[1] Kendall, K.E., Kendall, J.E., Systems Analysis and Design. Prentice Hall. 2011. New Jersey, USA.
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