#Design sequence diagram how to
#Design sequence diagram software

How to create a sequence diagram for a library management system So now that you know something about how sequence diagrams are put together, let’s move on to creating an example sequence diagram in the easy-to-use Gleek diagramming tool. If you want to read about more complex elements in sequence diagrams, check out this more detailed blog post: Sequence diagram with fragments: Loop, alternative, option or watch this video of a cashier example sequence diagram. Those are the basics about sequence diagrams and should be enough for you to understand our example sequence diagram. The length of the box tells you the duration of activity.

A vertical box called an activation bar is placed on the lifeline to indicate that the object is processing the message or carrying out a command. Once the CDR is done, the implementation stage (coding and unit testing) begins.When a message hits an object’s lifeline, that object can be activated. We illustrate how to perform effective design reviews in our Use Case Driven book. The CDR forms something of a reality check for your design. Once you've finished all the sequence diagrams for the use cases you're working on in the current release and updated your static model (class diagrams), you need to perform a Critical Design Review (CDR). If your mind is on drawing a flowchart, it's not going to be focused on this critically important set of behavior allocation decisions. In the ICONIX Process, the primary purpose of the sequence diagram is to make this behavior allocation visible so that you get it right. This allocation of operations to classes tends to be a make–or–break design issue.

#Design sequence diagram software

If you're trying to drive a software design from use cases, it's vitally important to get the allocation of operations to classes correct. In large part this is because drawing flowcharts simply misses the point of what you should be thinking about when you draw a sequence diagram. However, even though the notation supports it, we consider the practice of drawing flowcharts on sequence diagrams to be inadvisable, because it puts emphasis on the wrong part of the problem. UML 2.0 allows you to draw full–blown flowcharts on your sequence diagrams. Just as you drew one robustness diagram per use case, you'll also draw one sequence diagram per use case.ĭON'T TRY TO DRAW FLOWCHARTS ON SEQUENCE DIAGRAMS (FOCUS ON BEHAVIOR ALLOCATION INSTEAD) There's a direct link between each use case, its robustness diagram, and the sequence diagrams. But note that we advocate drawing your sequence diagrams in a minimal, quite specific format (which we describe fully in this chapter). You use sequence diagrams to drive the detailed design. Now it's time to make those statements very precise, to turn them into a detailed design that works within the Technical Architecture that you've defined. With preliminary design, you made some informal first guesses at how the classes will interact with each other.

When you draw sequence diagrams, you're taking another sweep through the preliminary design, adding in detail. 'If you figure that preliminary design is all about discovery of classes (aka object discovery), then detailed design is, by contrast, about allocating behavior (aka behavior allocation) – that is, allocating the software functions you've identified into the set of classes you discovered during preliminary design. PERMALINK UML Sequence Diagrams and detailed Object-Oriented Design