Data flow diagrams mainly explain the data flow taking place in a business information system. Logical data flow diagram depicts the ways a business operates and the physical flow diagram shows the ways the information system is implemented. The main focus of logical DFD is business activities and the main focus of physical DFD is the implementation of the system.
So, the differences between physical and logical data flow diagrams mainly come from their focus. A process is considered to be a business activity under the logical flow diagram. But a process is considered to be a software program or any manual procedure under a physical flow diagram.
Datastore is another area where we can find the difference between logical and physical flow diagram. Datastore in a logical flow diagram depicts the explanation of the ways the data are stored in different databases. Under physical flow diagram, data store means computer files, databases, and paper files.
The ways the data gets stored in the databases, paper files, or computer files are explained by a logical flow diagram descriptively.
A logical flow diagram can be understood by a non-technical person but a physical data flow diagram is highly complex and it can only be interpreted by the persons having prior knowledge and technical skills.
Therefore, it can be said that the flow diagram represents the flow of data of processes or a system. Logical and physical data flow diagrams or two types of data flow diagrams and they are different from each other. It can also be said that the physical flow diagram comes from a logical flow diagram. The most significant aspect of a flow diagram is that it helps in keeping the program highly organized.
The programmers can use data flow diagrams in planning the accomplishment of new programs efficiently. The programmers can also keep a constant track on the program with the help of data flow diagrams. In the domain of decision-building, the role of data flow diagrams is highly crucial.
In every program which is available to consumers, we can find there are several parts which help in making decisions based on the data. Such decisions can be taken either by any part of the program or by the users. Data flow diagrams support the programmers to figure out various options with the help of which the programs can be handled and data can be obtained.
Data flow diagrams can help the programmers to explain the functionalities of the program to any laypeople without using any technical terminologies or computer languages which might not be understood by the laypeople.
By the help of data flow diagrams, the programmers can explain the program to the people without wasting any time and effort in explaining different computer codes and languages to the non-technical people. Sometimes, the programmers realize the fact that there is always an effective way of optimizing the code. This realization takes place during a project is in its ongoing phase when the programmers find it difficult to figure out where to use the code. The programmers might also need to modify the codes so that they could accommodate them feasibly.
But with the use of a flow diagram, the programmers can able to visualize the consequences of injecting certain codes into the program. In understanding the logical movement of data in a business, the role of data flow diagrams can never be overemphasized. The systems analysts structure data flow diagrams as a tool which helps in depicting interrelated data flows and subsystems of an information system.
By the help of graphical representation of the movement of data storage and data transformation, the entire information can be obtained. The analysts usually gather sources of data processes data flows and data stores from initial organizational narratives which are provided by the users or get revealed by any data sources. This information is used to develop flow diagram based on the contexts available. The data flow diagram intricately explains the performance of the processes by different users, execution of the processes, performance of similar processes, combination of batch processes for effective processing, the combination of processes and partitioning of the processes into different programs.
These are the main areas which get represented by the help of data flow diagrams. For more information related to other topics and subjects, you also check with Global Assignment Help. Previous post. Next post. Skip to content What is Data Flow Diagram? Data Flow Diagram. No process. Premium Data flow diagram Words 6 Pages. It enables you to represent the processes in your information system from the viewpoint of data. Explain what a DFD is. Explain why constructing DFDs are important in arriving at a good software design.
Structured Analysis Structured analysis. HOME Flowcharting and data flow diagrams dfd are important in accounting information systems. Page 1 of 50 - About Essays. Data Flow Diagram Using Data Flow Diagrams Data flow diagram is used by system analyst to put together a graphical representation of data processes throughout the organization.
This is quite logical, because data can't transform on its own with being process. By using the thumb rule, it is quite easily to identify the illegal data flows and correct them in a DFD. A second class of DFD mistakes arise when the outputs from one processing step do not match its inputs and they can be classified as:.
A data store or data repository is used in a data-flow diagram to represent a situation when the system must retain data because one or more processes need to use the stored data in a later time. An external entity is a person, department, outside organization, or other information system that provides data to the system or receives outputs from the system. External entities are components outside of the boundaries of the information systems.
They represent how the information system interacts with the outside world. Top-down decomposition, also called leveling , is a technique used to show more detail in lower-level DFDs. Leveling is done by drawing a series of increasingly detailed diagrams until the desired degree of detail is reached.
As shown in the Figure, DFD Leveling is first displaying the targeted system as a single process, and then showing more detail until all processes are functional primitives. A context diagram gives an overview and it is the highest level in a data flow diagram, containing only one process representing the entire system.
It should be split into major processes which give greater detail and each major process may further split to give more detail. Processes in diagram 0 with a whole number can be exploded further to represent details of the processing activities. Example below shows the next level Diagram 1 of process explosion. Although the following level 1 DFD only has three processes, there are quite a few input and input from the processes to the external entities and that could end up to be a few cross lines among them in the diagram; to avoid this problem, we could use master and auxiliary view multiple views of the same external entity in the DFD.
If a process with a lot of data flow linking between a few external entities, we could first extract that particular process and the associated external entities into a separate diagram similar to a context diagram, before you refine the process into a separate level of DFD; and by this way you can ensure the consistency between them much easier.
Data flow diagrams are categorized as either logical or physical.
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