Depicting the division of system into smaller module
Facilitating less comprehending user of computer area to understand system to be done.
DIAGRAM CONTEXT
Consist of one process and depict scope from a system
Representing highest level of DFD depicting all input to the system and output of system
System limited by boundary (depicted by dash line)
There may not be any is depository ( storage)
ZERO DIAGRAM
Depicting process of DFD
Opening on by totally regarding system handled, showing existing especial process or function, data stream and external entity
At this level there enabled by the existence of data storage For process which not detailed again at level hereinafter hence enhanced by symbol ‘*’ or ‘ P’ by the end of process number
Input balance and output ( balancing) among diagram 0 with context diagram have to be looked after
DETAILED DIAGRAM
Representing diagram elaborating process there is in zero diagram or level above him
Level Numbering at DFD :
In one level shall not there are more than 7 process and maximal 9, if/when more hence must be done composition3
SPECIFICATION OF PROCESS
Every process at DFD have the specification of process
method level top used to depict process earn using by descriptive sentence
more level detailed that is process most under ( functional primitive) requiring more of structure specification
Specification of process will become guidance to programmer in making program ( coding)
Method which used in specification of process : breakdown of process in the form of story, decision table , decision tree
EXTERNAL UNITY
Something that beyond system, but it's given data into system or give data of system
Symbol with notation box
External entity do not including the part of system.
Naming :
● Name of terminal in the form of noun
● Terminal may not have the name of [is] same except its [is] same object (it) is true
CURRENT DATA
Representing place a stream of information
Depicted with connective straight line component of system
Data current shown with direction bow and line called a stream of data current
Data current stream among of process, data storage and show data current of data which in the form of input for the system
Guidance gift of name :
● Name of data stream which consist of some word stream attributed to continued line
● There may not be any data stream which its same name and gift of name have to express its contents
● Data stream which consist of some element can be expressed with element group
● Avoid usage of word ‘ data’ and ‘ information’ to give the name at data stream
● As possible the name of data stream written is complete.
Other rule:
Name of data stream which entered into a process may not equal with the name of secretory of process data stream
Data Flow which entered or go out from data storage needn't be called if :
● simple data stream and easy to comprehended
● Data stream depict all data item
There may be not any data stream from terminal to data storage or on the contrary because terminal non part of system, relation of terminal with data storage have to through process
Process
Process represent what done by system
Process can process data stream or data enter to become exit data stream
Functioning of process to transformation one or some input data become one or some output data as according to specification which wanted
Every process have one or some input and also yield one or some output
Process often is also referred by bubble
Guidance of gift of process name:
● Name of process consist of noun and vb. expressing process function
● Don't use word process as part of the name of bubble
● There may not be any some process owning the name is same
● Process must have number. Number sequence as possible follow process sequence or stream, but that way meaningless number sequence absolutely represent sequence process chronologically
DEPOSIT DATA
Data Storage represent existing data repository in system
Symbol with a couple of parallel line or two line wrongly one side from other side openly
Process can take data from or give data to database
Guidance to gift of name:
● Name have to express data of storage
● If its name more than one word hence have to say the word to joint.
DICTIONARY DATA
Functioning assist perpetrator of system to interpret application in detail and organizational all used by data element system precisely so that user and system analyst have same congeniality base about input, output, depository and process
At analysis phase, data dictionary used by communication means among of system analyst with user
At phase scheme of system, data dictionary used to design input, database and report
Data current at DAD have the character of globally, more detailed can be seen at data dictionary
Data dictionary load the followings :
● Name of data current : have to be noted so that reader which needing furthermore clarification about a data current can look for it easily
● Alias : alias or the other name can be written
● Data form: used to group data dictionary into its use time scheme of system
● Data current: showing where from data emit a stream of and where destination of data
● Clarification: giving clarification about meaning of data current
BALANCING IN DFD
Stream Data which entered and go out from one process have to same with data stream which entered and go out from detail process of level / level below
Name of data stream which entered and go out from one process have to same with name of data stream which enter into and go out from detail of process
Amount and name of external entity from a process have to same with name and amount of external entity from detail of process.
Things which must be gave attention to DFD owning more than one level:
Have to there are input balance and of output among one and next level
Balance among level 0 and level 1 seen at input / output of data stream or from terminal at level 0, while balance among level 1 and level 2 seen at input / output of data stream from pertinent process
Name of data stream, data storage and terminal every level have to be same if its same object
PROHIBITION ORDER IN DFD
Data current may not from direct external entity go to other external entity without passing a process
Data current may not from direct data deposit go to external entity without passing a process
Data current may not from direct data deposit go to the other data deposit without passing a process
Data current from one direct process go to the other process without passing a data deposit can be possible avoided
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