Benefits of Logical and Physical Data Flow Diagram

Data flow diagrams are categorized as either logical or physical. A logical data flow diagram focuses on the business and how the business operates. It is not concerned with how the system will be constructed. We can ignore implementation specifics such as, computer configuration, data storage technology, communication or message passing methods by focusing on the functions performed by the system, such as, data collection, data to information transformation and information reporting.

A physical data flow diagram shows how the system will be implemented, including the hardware, software, files, and people in the system. It is developed such that the processes described in the logical data flow diagrams are implemented correctly to achieve the goal of the business.

Benefits of Physical Data Flow Diagram

  • Clarifying which processes are manual and which are automated: Manual processes require detailed documentation and automated process require computer programs to be developed.
  • Describing processes in more detail than do logical DFDs: Describes all steps for processing of data.
  • Sequencing processes that have to be done in a particular order: Sequence of activities that lead to a meaningful result are described. For example, update must be performed before a producing a summary report.
  • Identifying temporary data storage: Temporary storage such as a sales transaction file for a customer receipt (report) in a grocery store, are described.
  • Specifying actual names of files and printouts: Logical data flow diagrams describes actual filenames and reports, so that the programmers can relate those with the data dictionary during the developmental phase of the system.
  • Adding controls to ensure the processes are done properly: These are conditions or validations of data that are to be met during input, update, delete, and other processing of data.

Benefits of Logical Data Flow Diagram

  • A logical diagram is drawn present business information and centered on business activities, which makes it an ideal communication tool when use in communicating with project users.
  • Logical DFD is based on business events and independent of particular technology or physical arrangement, which makes the resulting system more stable.
  • Logical DFD allows analyst to understand the business being studied and to identify the reason behind implementation plans.
  • Systems implemented based on logical DFD will be easier to maintain because business functions are not subject to frequent change.
  • Very often, logical DFD does not contain data stores other than files or a database, making less complex than physical DFD and is easier to develop.
  • Physical DFD can be easily formed by modifying a logical DFD.

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