Good Essay About Dfd

Data flow is a representation of data to a process or from a process. Another functionality of data flow is when it is used to represent the creation, deletion, or updating data that is in a database or file. There is also the representation of composite data flow which is a data flow that has other data flows.

Process decomposition

Functional decomposition is the process where a system is broken down to its smaller subsystems, sub-processes or processes. In this process, the smaller level will either show (reveal) additional detail or less detail. A decomposition diagram, is a diagram that is used to show the top-down decomposition of a system (Mall, 2014). It is a scheme that is used for numbering. It is used to aid in naming the tasks and how those tasks will be performed. It is an advanced process where labeling of tasks is done in a process. There is also the decomposition of DFDs. One type of decomposing DFDs is functional decomposition. It is the process of going from one single system to many component processes. It is a procedure that is considered to be repetitive. In this case, the level that is lowest is referred to as a primitive DFD. Another type of process decomposition is Level-N diagrams. It is a type of DFD where n nested decompositions have been done on a series of sub-processes from a process. It is done in a level-0 diagram.
There is also a context diagram that is worth mentioning. Context diagram is DFD whose scope is that of the organization and shows the boundaries of the system. It also shows the external entities that interact in the system together with the major information flow that occur between entities of the system. It is used to show the context with which the system will align. It is used to show the overall business process to be one process. It also represents the entire business process as just one process. It is also used to show the external entities that receive or contribute information to the system.
There are different levels of DFDs. There is Level 0 diagram which is DFD that is used to represent the major processes of a system. The data flow and data store are represented at a level that is considered to be high. Another type is Level 1 Diagram which is used to represent all processes which comprise of single process in the Level 0 diagram. There is also Level 2 diagram whose process have single process on Level 1 diagram.

Balancing

Balancing DFD is a process where inputs to a process and outputs from a process are conserved on the next level of decomposition. In the process of balancing, all the objects that are linked to a process are preserved so that they are in the next level. Care will have to be taken so that the sub-diagrams still has the data from the previous data flow (Völter et al., 2013). In popular diagrams, when undertaking decomposition of DFDs, the child diagrams will inherit the number ID of the parent diagram. In this case, the first child after the parent diagram will be 1.1 where the parent ID will be numbered 1.

Notations

There are different notations that are found in a DFD. There are four components that are assigned to different notations for their shapes. These are process, data store, sources/sink, and data flow. They all have different notations that will be used to represent the flow of data and information.

References

Mall, R. (2014). Fundamentals of software engineering. PHI Learning Pvt. Ltd..
Völter, M., Stahl, T., Bettin, J., Haase, A., & Helsen, S. (2013). Model-driven software development: technology, engineering, management. John Wiley & Sons.