DATA FLOW DIAGRAM

DATA FLOW DIAGRAM
Can be called the Data Flow Diagram (DFD). Describe the distribution of the modules in the system to a smaller. Easy to understand the less the field to understand the computer system that will be done
CONTEXT DIAGRAM
Consists of a process and describe the scope of a system . It is the highest level of the DFD that describes the entire system to input and output of the system. The system is limited by Boundary (depicted by broken lines). No storage (storage)
ZERO DIAGRAM
Describe the process of the DFD. Provide views on the overall system in which, showing the main function or process that is, the flow of data and entity external. At this level of data storage possible. For processes that do not detail again on the next level then added the symbol '*' or 'P' at the end of the process. Input and output balance (balancing) between 0 to diagram context diagram should be maintained
DETAILED DIAGRAM
It is a process diagram that decipher what is in the diagram zero level or above. Numbering level in the DFD:

In the one level there should be no more than 7 units and the maximum of 9, when more should be done in the decomposition
SPECIFICATION PROCESS
Each process in the DFD must have a specification process. At the top level method is used to describe the process can use a sentence with descriptive. On a more detailed level, namely on the bottom (functional primitive) requires specification of a more structured. Specification process will be the guideline for the programmer to make this program (coding). Methods used in the specification process: the process of disintegration in the form of a story, decision table, decision tree
ON FOREIGN
Something that is outside the system, but it provides data in the system or to provide data from the system. with the notation described. External entity not part of the system including. Naming: (The name of the form of noun. Terminal may not have the same name unless the object is the same.
CASH DATA
It is a place where information flows. Described the straight line that connects the components of the system. Flow data is shown with the direction arrows and the name on the flow of data that flows. Flow data flow between processes, data storage and data flow indicates that the form of data input for the system. Guidelines of the name: ( Name of the flow of data that consists of some words associated with the flow lines connect. No flow data is the same name and the name should reflect its content. Flow of data that consists of several elements can be expressed with the group element. Avoid using the word 'data' and 'information' to give a name to the flow of data. T he extent possible the flow of data is complete). Terms of others: (Name of the flow of data into a process may not be the same as the name of the data flow out of the process. Data flow into or out of data storage does not need to be given a name if: (Flow of data simple and easy to understand. Flow of data describing all the data items). No flow data from the terminal to the data storage, or vice versa because the terminal is not part of the system, the relationship with the terminal data storage must be through a process)
PROCESS
The process is what is done by the system. The process can process data flows or data entry into the flow of data out. The transform function of one or more of data input into one or more of the output data in accordance with the desired specifications. Each process has one or more inputs and produce one or more output. The process is also often called bubble. Guidelines of the process: (Name of the process consists of a verb and noun, which reflects the function of the process. Do not use the process as part of the name of a bubble. There may be some process that has the same name. The process should be given a number. Order number wherever possible to follow the flow of the process or sequence, but the sequence number does not mean that the absolute is a process in chronological order)
DATA STORAGE
Data storage is a storage place for data that exists in the system. Ilustratation with a pair of parallel lines or two lines with one side open side. The process can retrieve data from or provide data to the database. Guidelines of the name: (The name should reflect the data storage. If the name more than one word must be marked with the number )
DFD Symbols

DATA DICTIONARY
Working to help the system to interpret the application in detail and organize all elements of the data used in the system precisely so that the system analyst and have a basic understanding of the same input, output, storage and process. At the analysis stage, the data dictionary is used as a means of communication between the systems analyst with the. At the system design, data dictionary is used to design input, reports and databases. Flow data on the global DAD, further details can be seen in the data dictionary. load the data dictionary as follows: (Name of the data flow: must note that readers who need further explanation about a flow of data can find it easily. Other name of the data can be written when there is. The form of data: used to segment the data dictionary to use when designing the system. Flow data: indicates from which data flows and where the data. Description: provides an explanation about the meaning of the data flow
BALANCING IN DFD
Flow of data into and out of a process must be the same as the flow of data into and out of the details of the process on the level / levels below. Name of the data flow into and out of the process must match the name of the flow of data into and out of the details of the process. Number and name of an entity outside the process must be equal to the number of names and entities outside of the details of the process. The issues that must be considered in the DFD which have more than one level: (There should be a balance between input and output of one level and next level. Balance between level 0 and level 1 at the input / output of stream data to or from the terminal on level 0, while the balance between level 1 and level 2 is seen on the input / output of stream data to / from the process concerned. Name of the flow of data, data storage and terminals at each level must be the same if the same object
RESTRICTIONS IN DFD
Flow data may not be from outside the entity directly to other outside entities without going through a process. Flow data may not be from the savings directly to the data to outside entities without going through a process. Flow data may not be saving the data directly from the savings and other data without going through a process. Flow of data from one process directly to the other without going through the process of saving data should / be avoided as much as possible