Sequence diagrams are a valuable tool for documenting different parts of a system and the ways they interact with each other. While most developers and software architects create sketches and diagrams that contain UML elements, sequence diagrams have survived because they’re genuinely useful. They map and visualize the dynamic flow of messages across a system, and they’re comparatively easy to use. Although UML was a standard in the late 1990s, it became too complex, and UML fever drove people without software experience to design and control the software development process. The best way to make a sequence diagram is to start from the inside and work your way out and through. When correctly designed, they give big-picture insights.
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