QUIZ 5

DATA FLOW DIAGRAM


Data Flow Diagram

- Describing the distribution of system into small module is called data flow diagram(dfd)
- Make user easy to use which less understanding about computer and the system which will be done.


Contect Diagram

- Are a highest level from DFD which describe all of the scope of a system. This system is bounded by the boundary.
- Don’t have storage the data.

Zero Diagram

- Describe the process of DFD and support the all of opinion about the system that is handled, also need to storage data.
- For the process that not have more detail in next level so it must be added a symbol ‘*’ or ‘P’ in the end of number process
- Balancing of input and output between zero diagram and conteks diagram must be maintained

Detail Diagram

- Is the diagram that tell about the process what is there in zero diagram or the upper level
Numbering level in the DFD:


- In one level doesn’t have more than 7 process or the maximal is 9, if more than it so it need to dekomposition.


Specification Process

- In each process of DFD must have spesificasi process
- In top level method that used to describe a process, can use descriptif sentence
- In detail level that is in functional primitive need more structured spesificasi
- Spesificasi process will become orientation for the programmer to make coding
- The method that used in spesificasi process : the script of the process in a story, decision,decision tree.


External Entity

- Something that is in outside of system, but they give the data into system or give data from the system
- it is signed by notation box
- External entity is not part of system

naming:
- Name of terminal is noun

- The terminal is not have the same name exception in the same object


Data flow

- Is the palce of information flows
- Described by straight line that relate the component from the system.
- The flows data is signed by arrow and the line is given name the flows data that flow.

orientation prewsent name:

- The name data flow not be are same name and present name have agree with contents.
- Data Flow consists of some element can description are group element.
- Avoid to use a word like “data” and “information” for naming the data flow. And the name of data flow is written in complete name.



Certainty other:

- The name data flow that input in to a process not be same with the name data flow that output from process- Data
- Data flow that input or output from data storage not be need give name if:

- the data flow is simple and easy to understand
- the data flow describe all data item

- No be need data flow from terminal to data storage Because terminal is not part from the system, the terminal relation with data storage have to pass the process


Proces

- Process is what is worked by the system and it can manage the data or input data flow become output data flow.
- The function of process is transforms one or some input data become one or some output data with wanted specification .
- Each process have one or some input and produce one or some output.
- The process is also called bubble



The orientation naming process :

- Name of the process consists of verbs and nouns a that look up process function
- Don’t use “ process” as part of name a bubble.
- There is not same name in some process.
- The process given number : The structure of number must follow the flow proces, however it doesn’t mean absolutely and chronological structure process.


Data Storage

- Is a place to storage data in the system. The symbol is pararel line or two lines with one side is opened.
- Proces can take data from or given data to database
- The Orientation to give a name :
- The name must look like data storage.
- If name more than one word then must give continue sign.

Data Dictionary

- This function help user system for interpret aplication in detail and organize all elemen data are used in system exactly so that user and analysis system have same base understanding about input,output,storage and process.
- In analysis step, dictionary data is used as communication device between analyze system and user
- The data flow in DAD have global characterisic, more detail information can look in data dictionary


BALANCING in DFD

- Data flow that input and output from one process must same with detail data flow that in and out from under the level
- The name of data flow that input and output from a process must same with the name data flow process.
- Total and name external entitas from a proces have same with total and external entitas name from detail process.


The issues that must be considered in the DFD which have more than one level:

- There must be a balance between input and output of one level and next level

- Balance between level 0 and level 1 at input output of the flow of 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 and 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

- Data flow not from direct external entitas go on other external entitas without by a process.
- Data flow not from direct data storage go on external entitas without a process.
- Data flow not from direct data storage go on to other storage entitas without a proces
- Data flow from one direct process go on other process without a data storage or avoid it.