Comparison between business flow charts and data flow charts

Source: Internet
Author: User

Comparison between business flow charts and data flow charts

[Abstract] The business flow chart (transaction flow diworkflow) and data flow chart (Data Flow diworkflow) are two common graphical tools used in the development of structured information systems. This article describes the differences between objects, functions, basic symbols, and plotting methods, and also introduces their relationships.
[Keywords] Structured System Development Method System Research business flow chart data flow chart


I. Differences between business flow charts and data flow charts

1. Different description objects

The description object of the business flow chart is a specific business, and the description object of the data flow chart is a data flow.

Business refers to a series of activities necessary and logically related in enterprise management to fulfill a certain management function. During system research, we had a rough understanding of the main business of the system by understanding the organizational structure and business functions. HoweverOur understanding of the business is static, and the organizational unit maps to the business. The actual business flow is what we call a business flow.A complete business flow involves multiple departments and multiple data items.For example, the production business involves multiple departments, including procurement, finance, production workshop, and inventory. Multiple Data forms are generated, such as raw material purchase orders, accounts receivable and payments, and warehouse receiving orders. Therefore,When observing a business, we should take a series of activities of this business, that is, the entire process, as an observation object, not just a single activity, so that we can fully understand the business. Each step in a business processing process is graphically represented, and all processing processes are serialized in a certain order to form a business flow chart.1 shows the material management business flow chart of a company.


The data flow chart further abstracts and summarizes the business flow. Abstraction is manifested in the fact that it completely removes the specific material, leaving only the flow, processing, and storage of data. The general manifestation is that it can link various business processing processes to form a whole. From the perspective of Anthony Pyramid Model,The business flow chart describes the information flow, capital flow, and logistics in an enterprise.The data flow chart mainly describes the information flow. In addition, the data flow chart must be used with the description of the data dictionary to provide a complete and detailed description of the system's logical model.

2. Different Functions

A business flow chart is a "flow account" That graphically reflects the actual business processing process ". Drawing this flow account is helpful for developers to streamline and optimize their business processes. The business flow chart is simplified and easy to read and understand.The purpose of the flowchart is to analyze the business process and reorganize the business process based on the analysis of the existing business process to generate a new and more reasonable business process. Remove unnecessary and unnecessary business links, merge duplicate links, add necessary links, and determine the processes to be processed by the computer system, during the process of drawing the flowchart, you can find problems, analyze deficiencies, and improve the business processing process.

Data Process analysis mainly includes the analysis of information flow, transfer, processing, and storage. The purpose of data flow analysis is to discover and solve problems in data flow, such as poor data flow, unmatched data before and after, and unreasonable data processing process. By solving these problems, a smooth data flow will be formed as the data flow of the new system in the future. The data flow chart is more abstract than the business flow chart. It discards some physical entities in the business flow chart and is closer to the logic model of the information system. For a simple business, we can omit its business flow chart to directly draw a data flow chart.

3. Different Basic symbols

(1) common basic symbols of business flow charts are as follows, as shown in figure 2.


(2) The basic symbols of the data flowchart are shown in figure 3.


The basic symbols of the data flow chart are described as follows:
The external entity indicates the origin or termination point of the data stream. In principle, it is not the core part of the data flow chart, but the peripheral environment part of the data flow chart. In practice, it may be people, computer peripherals, files outside the system, etc. Enter the encoding attribute and name of the external object in the circle.
Data streams use arrows and data on them to indicate the direction of data flow. Data streams are composed of one or more data items.
Data storage represents the data storage link in the logical sense, regardless of the storage physical media and technical means. It is represented by a rectangle that opens on the right. The name of the stored data and dataset is filled in on the right of the image, and the logo of the data storage is filled in on the left.

Processing logic processing is also called processing or function. It includes two aspects: one is to change the data structure; the other is to add new content based on the original data content to form new data. Generally, a rectangle is used to indicate the processing logic. Enter the processing name in the lower part of the image, and enter the processing flag in the upper part.

The basic symbols of the business flow chart and data flow chart are not completely consistent in many teaching materials, and there is no unified standard yet. For example, some textbooks use circles to represent external entities, and some use rectangles to represent external entities. The symbols used by the two are different, but the meanings are the same. The business processing and storage symbols in the business flow chart are basically the same as those in the data flow chart. The business flow chart and data flow chart both have arrows, but their meanings are different: the arrow line in the business flow chart indicates the information flow direction, which has no name; the arrow line in the data flow chart indicates a data flow, which has a name and is usually written above the data flow.

4. The rendering process is different.

A business flow chart uses some specified symbols and links to represent a specific service processing process. The business flow chart is drawn based on the information obtained during the detailed investigation of the system. Based on the actual business processing process, it is drawn on the same graph with the specified symbols. There are no strict rules for it to be drawn, so you only need to briefly and truthfully reflect the actual business process. The "top-down" principle is also followed in the drawing process.

The data flowchart is drawn in a complicated way. It adopts the "top-down, layer-by-layer refinement" method, that is, the entire system is treated as a processing function, draw a rough data flow chart (top-level data flow chart) and analyze it layer by layer until the system is broken down into detailed low-level data flow charts. A is a top-level data flow chart of an institution's learning management system. Figure B and Figure C are the Layer 2 and Layer 3 data flowcharts of the learning management system.





Precautions for creating a data flow chart:

① The data flow chart is generally drawn from left to right. Mark external entities from the left, draw data streams generated by external entities, and draw elements such as processing logic, data streams, and data storage and their relationships, finally, draw the system external entity for receiving information on the right of the flowchart.

② Balance between parent and subgraphs. Subgraphs are detailed descriptions of the processing logic in the parent graph. Therefore, the input and output of data in the parent graph must be reflected in the subgraphs. The balance between the parent and subgraphs is the embodiment of the data stream conservation principle. For each data processing function, the number of input and output data streams before and after decomposition must remain unchanged.

③ The data stream must have at least one end of the connection handling box. Data Streams cannot be directly transmitted from external entities to data storage, or directly from data storage to external entities.

④ Data storage input/output coordination. Data storage must have an input data stream and an output data stream. The absence of any one means that some processing is missing.

⑤ Data processing inbound/outbound coordination. Only inbound and outbound data are not processed. Only outbound data without inbound data cannot be processed.

⑥ Reasonable name and accurate number. Numbers the basic elements of the data flow chart, which facilitates the compilation of data dictionaries and the reading and understanding of system designers and users.

2. Relationship between business flow charts and data flow charts

1. Both the business flow chart and data flow chart dynamically inspect the analysis object from the process perspective, and use graphical symbols to abstract the survey results.

2. the relationship between data and business is manifested in: data streams are generated along with the business process, which is a derivative of the business process; data is basically collected according to the organizational structure or business process; in data aggregation, we also set the data in different processing steps of the same business in the unit of business flow. The data flow chart is drawn according to the whole process of business processing.

3. There is a relationship between the data flow chart and the business flow chart. The business flow chart can export the corresponding data flow chart. There are two ways of thinking: one is to first sort the business process according to the business flow chart, and then separate the data and forms in the investigation process. Next, we will examine the data flow, the processing process and storage are serialized to form a complete data flow chart. The other is to separate the processing process from the business process, then we examine the input and output data of each processing process, and organically integrate the input and output data streams of all processing processes in the business process to form a complete data flow chart.

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