DFD constitutes system scheme tool that gets orientation on grooves data with decomposition concept can be utilized for delineation to analyses and also easy system design communicated by system professional to user and also program maker. Data flow chart called also Data flow diagram (DFD). DFD is model makings tool that enable system professional to figure system as a functional process network that linked each other with data path, well manually and also computerization. DFD this frequent so-called also by the name of Bubble Chart, Bubble is diagram, model processes, work flow diagram, or function model. DFD can make Easy user that insufficiently understand computer area for understands system who will be worked.
DFD'S makings steps :
1. Identification all outer unity that involved with system.
2. Input identification and output what do be engaged extern unity
3. Make picture of diagram context
DFD'S function:
1. DFD helps analysts sitem briefs informas about system, knowing relationship among system sub sub, fostering application effectively.
2. DFD functions as communication device that good among user and system analyst.
3. DFD can figure a number automation limitation for developmental alternative physical system.
CONTEXT DIAGRAM
Consisting of one process and figures scope of a system. Constituting supreme level from DFD what does figure all input goes to system and output of system. System drew the line by boundary (figured by dotted line). May not there is stored (storage). Context diagram in function map environment model (figuring relationship among
entities is extern, entry and system output), one that presentation with whorled
singles that represent system overall. DFD leveled figures system
as network of job among logistic one communicates mutually with flow
and laid up data, this model just model system of viewpoint
function
Context diagram is upstairs diagram, constituting diagram of one system which figure data flows in going and sticking out of system and ingoing and sticking out from entities extern. Thing Who shall be noticed:
1. Giving picture about exhaustive system
2. Terminal that give entry to source's so-called system
3. Terminal that accept sink's so-called output
4. There's only one process
5. May not there is data store
ZERO DIAGRAM
On this zero diagram what does amends just process and data path that link its process, meanwhile terminator's amount and incoming data path or outward from terminator, regular. Figuring process from DFD. give view thoroughly hit handled system, pointing out function or aught main process, data flow and eskternal entity. On this level is enabled marks sense storage's data. To process that don't elaborated again on succeeding level therefore enhanced symbol ‘ * ’ or ‘ p ’ at the early process numbers. Balance input and output (balancing) among diagram 0 by context diagram shall be petted
Thing that needs to be noticed:
1. Show store's data that is utilized
2. On process that don't elaborated again, add sign * at the early
process numbering
3. Balance among context diagram and zero diagram shall
Petted
DETAIL DIAGRAM
Detail diagram which is a diagram break even functional diagram and
each diagram linked by one systems logistic sub
One that has to be noticed:
1. Balance data flow among zero diagram and detail's diagram
2. On process that don't elaborated again, add sign * at the early numbering process
3. Balance data store who is utilized
Constituting diagram that describes to process what’s aught diagrammatically zero or level on it,
Numbering level on DFD:
In one advisable level has no is more than 7 processes and maximal 9, if more therefore has to be done by decomposition
SPECIFICATION PROCESSES
Each process on DFD shall have process specification. On top level methodic that is utilized to figure process can by use of descriptive sentence. On more level detail which is on lowermost process (functional primitive) needing more specification most structure.
Specification processes will be guidance divide programmer in makes program (coding). Method that is utilized in specification processes: breakdown of process in shaped story, decision table, decision tree.
OUTER UNITY
Beyond something system, but it gives data into system or gives data of system. At symbol with notation box. External entity excluding part of system.
Naming:
• Terminal name as substantive as
• Terminal may not have same name but object it really with
DATA CURRENT
Constituting place is adrift information. Figured by straight line that link component of system. Data current is pointed out with aim shoots and lining be given by name on current data which is adrift. Data current is adrift between process, storage's data and points out data current of data that as entry for system.
Name application guidance:
• Data’s streaming name which consisting of umpteen flow say to be linked by interlocking lining
• May not there is streaming data which its name with and name application shall reflect its content
• Data flow that consisting of umpteen element gets to be declared for by element group
• Avoid word purpose ‘ data ’ and ‘ information ’ to give name on streaming data
• As much as can data flow name is written fledged
Other rule:
• Data’s streaming name which turn in at a process may not same by the name of secretory data flow of that process
• flow's data ingoing goes to or issue of storage's data not necessarily been given name if:
• Simple data flow and perspicuous
• Data flow figures all item's data
• May not there is streaming data of terminal go to storage's data or on the contrary since terminal is not part of system, terminal relationship with data storage shall pass through process.
PROCESS
A process is an activity or work done by the person, machine or a computer from the data that flow into the process to produce data that will flow out of the 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 . Transform the process of working one or more of the input data 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 also often called bubble.
Guidelines of the process:
1. Name of the process consists of a verb and noun, which reflects the function of the process.
2. Do not use the process as part of the name of a bubble.
3. May not have some process that has the same name
4. 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 TROVE
Data storage is a storage place for data that exists in the system
at symbol 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:
1. The name should reflect the data storage.
2. When his name more than one word must be marked with the number.
DFD SYMBOLS
DATA DICTIONARY
Systems or data dictionary data dictionary is a catalog of data on information needs and the needs of an information system. Have functions 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 processing. At analysis, the data dictionary is used as a means of communication between the systems analyst with the user. At the system design, data dictionary is used to design input, reports and databases
DFD data flow on a global, more detailed information can be seen in the data dictionary.
Content Data Dictionary :
a. Name of the data flow.
b. Alias
c. Form of data.
d. Flow data.
e. Explanation. Description
f. Period. Period
g. Volume.
h. Data structure.
Load the data dictionary as follows:
1. Name of data flow: must note that readers who need further explanation about a flow of data can find it easily.
2. Alias: alias or other name of the data can be written if there is.
3. Forms of data: used to segment the data dictionary to use when designing the system.
4. Flow data: indicates from which data flows and where the data.
5. Description: to give an explanation of the meaning of the data flow
Balancing IN DFD
The 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 it. 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 the 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:
1. There must be a balance between input and output of one level and the next level.
2. 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.
3. Name of the flow of data, data storage and terminals at each level must be the same if its object same.
Restrictions in DFD
In drawing / DFD design there are several things that should be avoided, so the DFD
shows that overall the system will be designed, these things is:
1. Flow data may not be from outside the entity directly to other outside entities without going through a process.
2. Flow data may not be from the savings directly to the data to outside entities without going through a process.
3. Flow data may not be saving the data directly from the savings and other data without going through a process.
4. Flow data from one process directly to the other without going through the process of saving data should / be avoided as much as possible.
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