flow-oriented modeling in software engineering

flow-oriented modeling in software engineering

Introducation flow oriented modelling in software engineering:

Although stream oriented model is perceived as the obsolete method by some software engineers, it remains to remain one of the most widely applied requirements analysis notations being used today. Flow oriented model focuses on integrated analysis and design, is the place to down method and uses a graphic technique describing data flows and the transformations that are used as information moves from input to output.

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What is Flow Oriented Modeling ?

The flow oriented modeling represents how data objects are transformed at they move through the system. Derived from structured analysis, flow models use the data flow diagram, a modeling notation that depicts how input is transformed into output as data objects move through the system. Each software function that transforms data is described by a process specification or narrative. In addition to data flow, this modeling element also depicts control flow.

Although flow oriented modeling is perceived as an outdated technique by some software engineers, it continues to be one of the most widely used requirements analysis notations in use today.  Flow oriented modeling focuses on structured analysis and design, follows a top to down methodology and uses a graphical technique depicting information flows and the transformations that are applied as data moves from input to output.

The modeling tools that are used to build a data flow oriented model include context diagrams, data flow diagrams, entity relationship diagram, control flow diagram, state transition diagram, data dictionary, process specification and control specification. Although the data flow diagram (DFD) and related diagrams and information are not a formal part of UML (Unified Modeling Language), they can be used to complement UML diagrams and provide additional insight into system requirements and flow. The flow oriented modeling takes an input-process-output view of a system. That is, data objects flow into the software, are transformed by processing elements, and resultant data objects flow out of the software.

 

Data Flow Diagram :

The data flow diagram represents the flows of data between different process in a business. It is a graphical technique that depicts information flow and transforms that are applied as data from input to output. It provides a simple, intuitive method for describing business processes without focusing on the details of computer systems. DFDs are attractive techniques because they provide what users do rather than what computers do. In DFD, there are four symbols are used :

1. Process :

The circle represents the process. An activity that changes or transforms data flows. Since they transform incoming data to outgoing data, all processes must have inputs and outputs on a DFD.

2. Data Flow : 

The labeled arrows indicate incoming and outgoing data flow. Movement of data between external entities, processes and data stores is represented with an arrow symbol, which indicates the direction of flow.

3. Data Store :

The rectangle represents an external entity. A data store does not generate any operations but simply holds data for later access.

4. External Entity :

In Data Flow Diagrams external entities produce and consume data that flows between the entity and the system being diagrammed.

These data flows are the inputs and outputs of the DFD. Data objects are represented by labeled arrows, and transformations are represented by circles. The DFD is presented in a hierarchical fashion. That is, the first data flow model (sometimes called a level 0 DFD or context diagram) represents the system as a whole. Subsequent data flow diagrams refine the context diagram, providing increasing detail with each subsequent level.