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A Data Flow Diagram Information Technology Essay

Paper Type: Free Essay Subject: Information Technology
Wordcount: 1562 words Published: 1st Jan 2015

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Other than data flow, system requirement specification also need to be focuses. A requirements specification is a document which is used as a communication medium between the customers and the supplier. When the software requirement specification is completed and is accepted by all parties, the end of the requirements engineering phase has been reached.

In the end of the assignment, we will learn about the flow of system shown uses Data Flow Diagram and how Requirement Specification work.

2.0 Data Flow Diagram

Data Flow Diagram (DFD) is a graphical uses to represent the flow of data in a system. It shows the flow of data as they moving between input and output. The purpose of using Data Flow Diagram as a representative of a system is to provide a simple method of describing how the system work without needed to focus on the detail of the computer systems.

Symbol of Data Flow Diagram

A Data Flow Diagram uses 4 basic symbols as representative of process, data stores, data flow and entities. There are few different versions of DFD uses but still it is also serving as the same purpose.




It uses can represent a human, subsystem or system. This where certain data comes from / goes to. People often draw external entities on the edge of a diagram.


A process is a function or activity where the manipulation and change of data takes place. A process can be decomposed to better level of details purpose of representing how data is being processed within the process.

Data Store

A data store represents the storage of data required and which it produced by the process. Examples of data stores: database, membership forms, and more.

Data Flow

A data flow represents the flow of the system, whereby its direction represented by an arrow head that shows at the end of flow.

2.1 Level of Data Flow Diagram

A Data Flow Diagram is hierarchical, divide into 3 types:

Level 0

Level 1

Level 2

2.1.1 Level 0 DFD

In level 0 DFD, it only focuses on the context view of the flow in 1 process which is the most simplify version of DFD.

2.1.2 Level 1 DFD

In level 1 DFD, it goes deeper then level 0, which it expand the graphical model into more complex that represent the flow of data.

2.1.3 Level 2 DFD

In level 2 DFD, it focuses more closely in one particular process in level 1.

2.2 Rules of Data Flow Diagram

There are few rules that must be follow when creating a Data Flow Diagram (DFD):

Data flow that connects



A process to another process

Check mark symbol

A process to an external entity

Check mark symbol

A process to a data store

Check mark symbol

An external entity to another external entity

Check mark symbol

An external entity to a data store

Check mark symbol

A data store to another data store

Check mark symbol

2.3 Student Registration System

Below is an example of 3 different types of Data Flow Diagram uses in a simple student registration system for a college:

2.3.1 Level 0:

Registration Form

Student registration system


Confirmation Letter

2.3.2 Level 1:




Open course


Accept / Reject


Registration form


Course info

Course enrollment





Student info


Confirmation letter






Update info

2.3.3 Level 2:


Open course






Registration form


Course info




Course enrollment


Confirmation Letter






Student info


Update info








Course payment method

Receipt issued






Update info

3.0 Requirement Specification

In a large project the analyst could also have a number of people work under them. Theses extra staff would carry out the questionnaires, observations and interviews, required to develop the overall specification.

When developing a project, an agreement between the client and project team are formed. Document of requirement specification gave the information to client or customer regarding the project.

3.1 Layout of Requirement Specification

The requirement specification is carefully listed and highlighted according the following:

Scope of the system






Processing requirement


3.1.1 Scope of the system

This offers a context for the system within the organization. For instance, the scope will regularly define what it will not do and general explanation of what it will do.

3.1.2 Objective

It laid out point by point so it is clear define that what the system needs to do. Table or bullet points could be used in this process.

3.1.3 Timing

In this section, it provides a timeline of how the project will proceed and the time require for it to be done.

3.1.4 Constraints

It is referring to the budget and manpower that which is available for the project.

3.1.5 Inputs

In this section, it defines what inputs are needed by the system. It will provide outline details of the input screens, data capture forms, automated system feeds and more. It doesn’t try to be very technical at this point instant it just an overall idea of what will be accepted into the system and how this is to be achieved.

3.1.6 Outputs

A system has to produce an output in one form or another. In this section, it will describe the expected form of outputs. For example, output viewing screen, printed reports and graphs, files created and stored, and any output data feed to other system and so on.

3.1.7 Processing requirement

Between the process of Input and Output, processing in the middle is required. This part of Requirement Specification defines the processing to be carried out. Processing details are include:

– Procedures

– Validation details

– Acceptable limits of processing times

3.1.8 Contract

The requirements specification is in result of a contract between the end user and the people that responsible for delivering the project.

3.2 Important of Requirement Specification

It’s important to note that a requirement specification contains functional and non-functional requirements only; it does not offer design suggestions, possible solutions to technology or business issues, or any other information other than what the development team understands the customer’s system requirements to be.

A well-managed requirement specification could accomplish four major goals:

It provides feedback to the customer –

A requirement specification is the customer’s assurance that the development organization understands the problem and issue to be solved and the software behavior necessary to locate those problems. Therefore, it should be written in standard language, in an explicit manner that may also include charts, data flow diagrams, table, decision tables, and so on.

It decomposes the problem into component parts –

The simple act of writing down software requirements in a well-designed format organizes information, places borders around the problem, solidifies ideas, and helps break down the problem into its component parts in an orderly fashion.

It serves as a input to the design specification –

As mentioned previously, the requirement specification serves as the parent document to subsequent documents, such as the software design specification and statement of work. Therefore, the SRS must contain enough detail in the well-designed system requirements so that a design solution can be planned.

It serves as the parent document –

For testing and validation strategies that will be applied to the requirements for verification.

4.0 Conclusion

In system analysis and design, it focuses on the improvement of creating a good system of information data. By learning the proper way of analyzing and designing / developing a system, it could lead us into deeper understanding about the system.

In the above assignment we have learn the usage of Data Flow Diagram which serve as a guide for developer and analyst to check the flow of the system, and we also have learn that when creating a system software, a documentation regarding the software project are also an important step to do.


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