After successive levels of data flow diagrams are complete, systems analysts use them to help catalog the data processes, flows, stores, structures, and elements in a data dictionary. Of particular importance are the names used to characterize data items. When given an opportunity to name components of data-oriented systems, the systems analyst needs to work […]
Read More...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. As a document, the data dictionary collects and coordinates […]
Read More...The Data Repository
Although the data dictionary contains information about data and procedures, a larger collection of project information is called a repository. The repository concept is one of the many impacts of CASE tools and may contain the following: Information about the data maintained by the system, including data flows, data stores, record structures, elements, entities, and […]
Read More...Defining the Data Flows & Describing Data Structures
Data flows are usually the first components to be defined. System inputs and outputs are determined from interviewing, observing users, and analyzing documents and other existing systems. The information captured for each data flow may be summarized using a form containing the following information: ID, an optional identification number. Sometimes the ID is coded using […]
Read More...Logical and Physical Data Structures
When data structures are first defined, only the data elements that the user would see, such as a name, address, and balance due, are included. This stage is the logical design, showing what data the business needs for its day-to-day operations. As we learned from HCI, it is important that the logical design accurately reflect […]
Read More...Data Elements (The Data Repository)
Each data element should be defined once in the data dictionary and may also be entered previously on an element description form, such as the one illustrated in the figure below. Characteristics commonly included on the element description form are the following: Element ID. This optional entry allows the analyst to build automated data dictionary […]
Read More...Data Stores (The Data Repository)
All base elements must be stored in the system. Derived elements, such as the employee year-to-date gross pay, may also be stored in the system. Data stores are created for each different data entity being stored. That is, when data flow base elements are grouped together to form a structural record, a data store is […]
Read More...Creating the Data Dictionary
Data dictionary entries may be created after the data flow diagram has been completed, or they may be constructed as the data flow diagram is being developed. The use of algebraic notation and structural records allows the analyst to develop the data dictionary and the data flow diagrams using a top-down approach. For instance, the […]
Read More...Using the Data Dictionary
The ideal data dictionary is automated, interactive, online, and evolutionary. As the systems analyst learns about the organization’s systems, data items are added to the data dictionary. On the other hand, the data dictionary is not an end in itself and must never become so. To avoid becoming sidetracked with the building of a complete […]
Read More...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 […]
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