DATA FLOW DIAGRAM (DFD)

Data Flow Diagram

Describe the system distribution in the small module. Make easy use less realize the computer area for an understand system to worked.

Context Diagram

Consist of one process and describe the scop from any system. And then is a high level from the Data Flow Diagram to describe all input to the system and output from the system. The context diagram usually limitted by Boundary. And then not to be any storage.

Zero Diagram

Describe the process from the Data Flow Diagram. Give opinion according to comprehensive hit the system to handled, show the fuction or important system exiting, data flow and external entity. In this level maked existence the data storage. For the process not be detailed againt in the next level so to added the symbol ‘*’ or ‘P’ in the end of process number. Balancing of the input and output between zero diagram with context diagram must to take care.

Detail of Diagram

That is a diagram to decomposing the process what is there in the zero diagram or on the level.

Level numberizatio in the Data Flow Diagram:
- Level name is 0, diagram name is context, and there is not the number of process.
- Level name is 1, diagram neme is 0 (zero) diagram, and the number of process is 1.0, 2.0, 3.0, etc.
- Level name is 2, diagram name is 1.0, and the number of process is 1.1, 1.2, 1.3, etc.
- Level name is 3, diagram name is 1.1, and the number of process is 1.1.1, 1.1.2, etc.

In the one level must be not found more from 7 process and maximal is 9, when be more so must done decomposition.

Process Spesification

Every process in the Data Flow Diagram must heving the process spesification. In the top level method to used for describe the process can by using descriptive sentence. In the level to more detail is in the most under process (functional primitive) need the more structured spesification. Process spesification will be guide for programer in the make the program (coding). Method to used in the process spesification is process explanation in the form of story, decision table, and decision tree.

Unitary Outside

Certain beyond the system, but he give the data to in the system or give the data from the system. Usually symbolized with notation box. External entity not to belong part from system. Nomenclature is :
- The terminal name is shaped noun.
- The terminal can be not have same the name except the object really same.

Data Current

Data current is a place currences information. Described with straight line tto connect the component from the system. Data current showed by arrow direction and the line given the name on data current to flow. Data current to flow in the process, data storage and to show the data current from data to shaped the input for system. Guide the gift of the name is :
- Name of data flow consist of many word flow to connected with line continues.
- There may not be any data flow it’s the same of the name and gived the name must to reflect the contents.
- Data flow consist of many element can to asked with element group.
- Avoid to use any word is ‘data’ and ‘information’ for give the name in the data flow.
- The name of flow can be to written complete.

Rule other:
- Name data flow to come in a process not to be same by name of data flow to out from the process.
- Data flow to come in or out from the data storage can be not given the name when :
a. The simple of data flow and easy understood.
b. Data flow to describe all data item.
- There may not be any data flow from terminal to data storage or on the contrary because the terminal not a part from system, the connection of the terminal by data storage must pass the process.

Process

Process is a what to working by system. Process can to cultivate the data or data flow come to be out of data flow. The function of process is transformation the one or many input data be one or many output data appropriated with spesification to desirable. Any process have a one or many input and produce one or many output. The process often also called as bubble.

Guide the gift of the name process is :
- Name of process consist of many verb and noun to reflect function of the process.
- Don’t use process word as part from name a bubble.
- There may not be any process to have the same of the name.
- The process must given the number. Sequence the number can be to follow the flow or sequence the process, but such be sequence the number meaningless absolutely is the sequence of process according to chronological.

Data Storage

Data storage is a data repository in the system. Symbolized with a pair parallel line or two line with one of the side opened. The process can be take the data from or give the data to datebase. Guide the gift of the name is :
- The name must be reflect the data storage
- When the name be more from one word so must to take sign continues

Data Dictionary

The function of data dictionary to help a system user for interprate the aplication to detail and to unite all data element to used the system be exacttly so that user and system analyst have a same base explanation about input, output, storage, and process. In analysis stage, data dictionary to use as a communication tools that is analys system with user. In system planning stage, data dictionary to use for plan the input, report, and database. Data current in the Data Flow Diagram has global, more detail of explanation can be look in the data dictionary.

Data dictionary hold matter as follow is :
- Name of data current : must be registerred so that reader need a furthe more explanation about of a data current can be find so easy.
- Data form : to use for unite the data dictionary to use timer the system planning.
- Data current : show whence a data to flow and where a data to go.
- Explanation : give explanation about meaning from data current.

Balancing in the Data Flow Diagram

Data flow to come in and out from one process must be same with data flow to come in and out from detail of process in the level or stage under. Name of data flow come in and out from one process must be same with name of data flow to come in and out from detail of the process. Total and outside of entitas name a process must be same with total and outside of entitas name from detail of the process. Matter that must be played a Data Flow Diagram to have more one level is :
- Must found balancing input and output the one level and other level.
- Balancing the 0 level and 1 level can be look in the input or output from data flow to and or from terminal in the 0 level, while be balancing the 1 level and 2 level can be look in the input or output from data flow to or from process cornerned.
- Name of data flow, data storage, and terminal in the every level must be same if same object.

Prohibition in the Data Flow Diagram

- Data current can be not from direct outside of entitas to go to other outside of entitas without pass a process.
- Data current can be not from direct data saving to go to outside of entitas without pass a process.
- Data current can be not from direct data saving to go to other data saving without pass a process.
- Data currrent from one direct process to go to other process to pass a data saving can be may a void.