Data Flow Modeling

When data flow modeling is used to model a system’s functionality, following points need to be remembered

• Data flow model captures the transformation of data between processes/functions of a system. It does  not represent the control flow information that is occurring in a system to invoke certain functionality.
• A number of parallel activities are shown in this diagram where no specific sequence among these activities is depicted
• All the previous models that we studied like business process models, state transition diagrams, are used to capture business domain irrespective of their automation.
• However, in data flow models, we represent only those processes which we need to automate as they involve certain computation, processing or transformation of data that can be best implemented using  an automated system.
• For example, we may consider a mail desk in an office that receives mail and just forwards it to their respective addressees. In this example, as the mail desk does not process the mail, just forwards it,  therefore it does not include any process that need to be automated. Hence, we shall not use data flow diagrams to model this process.
• In nutshell, processes that just move or transfer data (do not perform any processing on that data), should not be described using data flow models.
• Taking the same example, if we modify the scenario such that a mail desk clerk receives the mail, notes it down into a register and then delivers it to their respective addressees then a processing has got involved in this scenario. At least one process is there that can be automated. That is, the recording of mail information into the register. Now we can use a data flow model in which wehall use a data transformation that captures the detail of recording mail information into a register (or a data store). Thus with this addition, it makes sense to use data flow model to capture the details of this process. 

Next post will be Typical Processes in data flow.