DATA FLOW DIAGRAM

Data Flow Diagram (DFD) is a diagram using the notation-notation to describe the flow of data from the system, which is very helpful to understand the logic of the system, and structure clear.
DFD is a tool in help describe or explain the system that is running logical.

DFD are often used to describe a system that already exists or the new system will be developed logically without considering the physical environment where the data flow or save.DFD is a methodology used in the development of a structured system.

DFD symbols used:
1.external entity

external entity is an entity in the environment outside the system that can be a person, organization or other system that is in the outside environment that will provide input or receive output from the system.
most of this external entity is:

-an organization, department within the company but outside the system under development
-person or a group of people in the organization but outside of that system is being developed
-an organization located outside the organization
information system-the other outside the system under development
-original source of a transaction
end-recipient of a report produced by the system

2.data flow

Data flow through the system, starting with some input and modified or processed into output. Flow data (Data Flow) with a given symbol the arrow.

in drawing data flow in DFD needs to draft a few to note are:

• The concept of packet-data
  when two or more data flows from a source that should be considered the same as a single flow
• The concept of data-flow spread
  flow of data spread shows a number of copies of the same data flow from the same source to a different destination
• The concept of data-gather
  gather flow data shows that some of the different data flows from different sources join together towards the same goal
• The concept of source-destination flow data and
  all the flow data must be generated from a process to a process

3.process

Is the activity or work done by the person, machine or computer from a flow of incoming data in the process to produce data that will flow out of the process or to change the input into output. A process can be indicated with the symbol of the circle.

Each process must be given the explanation that is:
1.Identifikasi process
included a number that indicates the number of reference and the process is written at the top of the symbol in the process

2.Nama process
shows what is done by the process

3.process

4.data store

Data stored for the next. Savings in the DFD data symbol with a pair of parallel horizontal lines that closed in one of the edges.

form of data flow diagram
There are two forms of the DAD data flow diagrams and physical data flow diagram data flow logikadiagram used to describe the physical system that ada.Sedangkan logical data flow diagram is used to delineate the proposed system.

guidelines drawing DAD
1.identificate first all outside the unit involved in the system
2.identificate all input and output involved in union with the outside
3.draw first a context diagram.
4.draw chart tiered process for all existing DAD

5.draw sketches for the overview diagram on the chart based on the tiered
6.draw DAD-level to the next level, for each process is broken-parsed according to the chart state
7.after all levels drawn DAD, DAD is drawing to a management reporting drawn separately

data dictionary is a catalog of facts and data information needs of an information system.
content data dictionary:
1.nama flow data
data dictionary is based on the data that flows in the name of the DAD data flow should also be noted in the data dictionary

2.Alias
alias is needed because the data have the same name that is different to the one with the other

3. form of data
dictionary is used to segment data into the system uses during the design

4.data flow
shows the data from which to goal

5.penjelasan
explanation can be charged with the particulars about the flow of data

6.periode
indicates when the occurrence of flow data

7.volume
noted that volume was about average and peak volume of flow data

8.data structure
shows the flow of data recorded data dictionary consists of items of data what