Figure1 shows the anatomy of a sequence diagram. Activations are represented by narrow rectangles that run down lifelines. When a message is passed, the object on the receiving end is said to be activated. Lifelines have arrows pointing to other lifelines, and these arrows represent participants calling methods on each other more formally, the participants are passing messages to one another.
Participants are represented as boxes atop sticks called lifelines. These objects, called participants, might be class instances, user interfaces, external systems, or just about anything that participates in a running program. Sequence diagrams are a great way to see how objects in a program interact. In this tutorial, I'll go through that streamlined process step by step. When I started working with the application, each diagram took an hour or so to create, but I've streamlined the process to about 20 minutes. I use Google Docs Drawings to create sequence diagrams for technical articles I write. Moreover, multiple people can work on the same drawing at once. Aside from supplying the basic drawing primitives you'd expect (lines, shapes, text, and so on), it features powerful ways to lay them out on screen. At first glance, the app looks about as sophisticated as Microsoft Paint, but looks can be deceivingand definitely are in this case. Google Docs Drawings is the newest application in the Google Docs lineup.