DATA FLOW DIAGRAM

DATA FLOW DIAGRAM

Data flow diagram is also called the Data Flow Diagram (DFD).DFD function to describe the existing system or the new system will be developed without considering the logic of the physical environment where the data flows, or where data disimpan.DFD can also explain the flow of data in the system with a clearly structured.

Context Diagram

1. Consists of a process and describe the scope of a system

2. Is the highest level of the DFD that describes the entire system to input and output of the system

3. System is limited by Boundary (depicted by broken lines)

4. There may not be storage (storage)

Zero Diagram

Zero diagram is a chart that describes the process of DFD. This diagram provides a view of the overall system shows that the main function of the process or the flow of data and the external entity. At this level there is a data storage.

Detailed Diagram

Is a diagram that decipher what is the process in the diagram zero level or above.

Numbering level in the DFD:

In one level there should be no more than 7 units and the maximum of 9, when more should be done in the decomposition.

Specification Process

Each process in the DFD must have a top-level specification process . method that is used to describe the process can use a sentence with descriptive, and on a more detailed level, namely on the bottom (functional primitive) require a more structured specification, process specification will be the guidelines for a programmer to create the program.

External Entity

Unit outside is something that is outside the system, but provide data in the system or to provide data from an external system. Entity not including part of the system, the symbols with the notation.

Rules for naming:

1. The name of the form of noun

2. Terminal may not have the same name unless the object is the same

Data Flow

Data flow is the information flow is depicted with a straight line that connects the components of the system. Data flow direction is indicated with arrows and lines give the name on the flow of data flow. Flow data that flows between processes, data storage and data flow indicates that the form of data input to the system.

Guidelines of the name:

1. Name of the flow of data that consists of some words associated with the flow lines connect

2. No flow data for the same and the name should reflect its content

3. The flow of data that consists of several elements can be expressed with the group element

4. Avoid using the word 'data' and 'information' to give a name to the flow of data

5. Wherever possible the complete flow of data is written

Other provisions:

1. Name of the flow of data into a process may not be the same as the name of the data flow out of the process

2. Data flow into or out of data storage doesn’t need to be given a name if:

a. The flow of data simple and easy to understand

b. Describes the data flow of all data items

3. There can be no flow of data from the terminal to the data storage, or vice versa because the terminal is not part of the system, the relationship with the terminal data storage must be through a process

Process

The process is what is done by the system, can process data streams or input data into output data stream. Each process has one or more inputs and produce one or more output.

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.

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 doesn’t mean that the absolute is a process in chronological order

Data Storage

Data storage is a storage place for data that exists in the system, which symbol with a pair of parallel lines or two lines with one of the side open. The process can retrieve data from or provide data to the database.

Guidelines of the name:

1. The name should reflect the data.

2. When his name more than one word must be marked with the numbers.

Data Dictionary

Data Dictionary functions to help the system to interpret the application in detail and manage all elements of the data used in the system right 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.

Data dictionary contains the following:

1. Name of data flow: must note that readers who need further explanation about a flow of data can find it easily

2. Alias: initials or other name of the data can be written when 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 or levels below it. 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 next level

2. 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

3. Name of the flow of data, data storage and terminals at each level must be the same if the same object

Restrictions In DFD

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

Reference:

ER, Ngurah Agus Sanjaya. Slide presentation Part 4 - Data Flow Diagram.