How to Make a Sequence Diagram
A sequence diagram is used to analyze, document or validate the logic in the system being reviewed. This visual model uses boxes and lines to detail the sequence of events for a system. A series of sequence diagrams can be used if the process is complex. Draw a simple sequence diagram by hand or use a software tool such as Microsoft Visio for more detailed diagrams. The following example details a sequence diagram for checking out at a grocery store.
Instructions
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List the steps in the process in their sequential order. For the example of checking out at a grocery store, the steps are "Choose food," "Place food on counter," "Pay for food," "Bag food" and "Leave store."
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Write the steps on the paper in a column on the left side. Begin with step one in the top-left corner with step two written below step one. Continue with all steps, allowing at least 1 inch between steps to create the diagram.
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Write the physical items needed for the process across the top of the paper in the order that they are used from left to right. In this example, write "Customer" first followed by "Cart," "Counter" and "Bag." Space each item far enough to allow for the diagram details, usually at least 2 inches.
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Draw a dashed line down from all of the items written across the top so the line stops even with the last step in the process listed vertically on the left of the paper. This line represents time during the process where that item is used. Draw a thin rectangle along the dotted line under the customer item so it extends vertically along the entire sequence of events. This rectangle represents actions or processes being performed by that person.
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Draw a thin rectangle along the dotted line under the cart item so it is aligned horizontally with the "Place food in cart" step. Draw a thin rectangle along the dotted line under the counter item so the rectangle is aligned horizontally with the "Place food on counter" step through "Pay for food" steps. Draw a thin rectangle along the dotted line under the bag item so it aligns horizontally with the "Place food in bag" through the "Leave store" steps.
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Tips & Warnings
Use a software program such as Visio to create professional-looking diagrams that are easy to read.
