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Reading a Data-Flow Activity Diagram

publish date: 2026/06/08 10:49:36.572762 UTC

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The diagram below shows an activity diagram modeling the data processing involved in the insulin pump software.

Blood sugar sensor Get sensor value Sensor data Compute sugar level Blood sugar level Calculate insulin delivery Insulin requirement Calculate pump commands Pump control commands Control pump Insulin pump

In this data-flow activity diagram, what do the plain rectangles (without rounded corners) represent?

Correct Answer

Data objects — data that flows between processing steps

Explanation

In a UML activity diagram used as a data-flow model, rounded rectangles represent activities (the processing steps), and plain rectangles represent data objects (the data that flows between the activities). Arrows show the data flowing between activities and data objects. This is consistent with the UML activity diagram notation described in Section 5.1.

Reference

Software Engineering, Ian Sommerville, 10th edition

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