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CS507 - Information Systems - Lecture Handout 24

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Symbols used for flow charts

Symbols

The symbols have already been briefly stated in the previous Lesson. Following would explain these symbols in detail.

Symbols

Symbols 1

Symbols 2

Symbols 3

Symbols 4

Good Practices

Recommended practices for flow charts:

  • Ensure that the flowchart has a logical start and finish.
  • In drawing a proper flowchart, all necessary steps that are a part of process should be listed out in logical order.
  • The flowchart should be clear, neat and easy to follow. There should not be any room for ambiguity in understanding the flowchart.
  • It is useful to test the validity of the flowchart.

Following can be seen as a comprehensive example of how the symbols of flow charts as defined above are used.

Good Practices

As shown in the above diagram, the bidding process starts with issuing prequalification document. The purpose is to seek preliminary information so as to decide whether the bidder qualifies for submitting a bid. Where the information does not support the criteria, the bidder is not further allowed to proceed. Other wise, the Request for Proposal is issued to the bidder.

Since the process cannot be summarized in one page, it is continued to the next page by using an off page connector.

Good Practices 1

On the next page, another off page connector is used to give reference of the page from which it is being continued. The process continues with issuance of RFP document and receiving the filled RFP document. An evaluation is made of the bidders on technical and financial bases. In case the criteria are not met, the unsuccessful bidders are intimated and process for this class ends. Where the criteria are met, contract is awarded. The process termination is shown by using the terminator symbol.

Advantages

  • The benefits of flowcharts are as follows:
    • Communication – Flowcharts are better way of communicating the logic of a system to all concerned. Flowcharts are more focused on decision making and activities relating thereto taken in a set of relevant processes.
    • Proper documentation – Program flowcharts serve as a good program documentation, which is needed for various purposes.

Advantages

  • Efficient Coding: The flowcharts act as a guide or blueprint during the systems analysis and program development phase.
  • Proper Debugging: The flowchart helps in locating and correcting errors (Also called debugging).
  • Efficient Program Maintenance: The maintenance of operating program becomes easy with the help of flowchart.

Data Flow Diagram

"A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system."

The purpose of data flow diagrams is to provide a linking bridge between users and systems developers.
The data flow diagrams are:

  • Graphical, eliminating thousands of words;
  • Hierarchical, showing systems at any level of detail; and

They have less jargon, allowing user understanding and reviewing.

Data flow diagrams facilitate users to understand how the system operate. DFD’s also help developers to better understand the system which helps in avoiding delays in proper designing, development, etc. of projects.

Following are the symbols of used in the making of flow charts.

Data Flow Diagram

Data Flow Diagram 1

Data Flow Diagram 2