A Data Flow Diagram Information Technology Essay

A Data Flow Diagram Information Technology Essay 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. Description Symbol Entities 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. Process 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 YES NO 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 Student Confirmation Letter 2.3.2 Level 1: 1.0 Verify Availability Open course D1 Accept / Reject result Registration form Course Course info Course enrollment 2.0 Enroll Student Student Student info Registration Confirmation letter D2 3.0 Confirm Registration Student Update info 2.3.3 Level 2: Course Open course D1 1.0 Verify Availability Advisor Registration form Student Course info Reject 1.1 Permission Course enrollment Accept Confirmation Letter 2.0 Enroll student Student Registration Student info D2 Update info Payment Registration fee 2.1 Account D3 2.2 Course payment method Receipt issued 2.2.2 2.2.1 Installment Financial aid 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 Objectives Timing Constraints Inputs Outputs Processing requirement Contract 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 doesnt 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 Its 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 customers 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  customers 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.