Konsep Data Flow Diagram IPO:
Input →Process → Output Data→ Process → Information
Data flow diagram is a graphical technique that depicts inform...
Input →Process → Output Data→ Process → Information
Data flow diagram is a graphical technique that depicts information flow and the transforms that are applied as data moves from input to output.
Characteristics of DFD
Graphic Partitioned Hierarchic Multidimensional Emphasize flow of data Viewpoint of data and process
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
The Symbols DFDs use four basic symbols that represent processes, data flows, data stores, and entities • Gane and Sarson symbol set • Yourdon symbol set
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Symbols for DFD Yourdon notation (sumber: www.yourdon.com) External Interactor
External Entity: Source or destination of data
Process name
Process: Action on data
Data store
Data Store: Storage of data
Data Flow: Data Transfer Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Context Diagrams
A context diagram is a top level (also known as Level 0) data flow diagram. It only contains one process node (process 0) that generalizes the function of the entire system in relationship to external entities. Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Creating a Set of DFDs Create a graphical model of the information system based on your fact-finding results Performing three main tasks Step 1: Draw a context diagram Step 2: Draw a DFD level 1 Step 3: Draw the lower-level diagrams
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Draw a Context Diagram Drawing Guidelines 1. Draw the context diagram so it fits on one 2.
3. 4. 5. 6.
page Use the name of the information system as the process name in the context diagram Use unique names within each set of symbols Do not cross lines Provide a unique name and reference number for each process Obtain user input and feedback
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
External Entity External entity represents the sources and destination of data created by the system. External entity represents the immediate interface of the system with the external world. When an external source of data is also a destination for data, a loop or occurrence number may be used. In case the destination or use of data created by the process are not known, the flow simply points outside the system. Similarly, data flows may originate from “nowhere”. Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Process Boxes Each processes box in a DFD describes an action on data. The Identifier. A number indicating the sequence of the process. The Action. A verb specifying the action on which it is performed on the data. The Actor or Place. A noun indicating who performs the action or where it is performed.
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Data Flow Arrows Data flow arrows link all the process boxes and data stores in DFDs. Data flows should be labeled, except in case the data flows into and out of simple files. DFDs show only the flow of data, not materials. A DFD depicts information flow without explicit representation of procedural logic (e.g., conditions or loops).
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Data Store Rectangles Data stores can be manual files or computer files. The type of file is not indicated. Only in case the data store is altered the flow is not indicated. A simple access is not indicated. A data store is never the direct recipient of unprocessed data from external sources or from other data stores nor is data from a data store ever directly delivered to an external sources. There must be a process step in between.
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Examples of Data Stores
Read
Read/ Write
Write
A data item is created or deleted or updated in the data store by a process Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Rules for Constructing DFD
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
DFD Not Allowed Flows
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
DFD Not Allowed Flows
If part of our system
If not part of our flow ignore
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Data Flows Only one direction of flow between processes
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Data Flows Joins & forks allowed only if exactly the same data
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Data Flows Cannot go directly back to the process it leaves
Sumber: www.yourdon.com
Edited by: Yudi Priyadi
Data Flows Data which moves together should be shown in a single data flow invoice payment
