How to show if condition on a sequence diagram

Question

I was wondering  how can one represent  if  statement on a sequence diagram   if  somethingShouldBeDone              Do it   else             Do something else     Can it be represented at all  The thing is     in my code  fair amount of conditions are checked to determine a variety of actions  If i am going to show the actions  I d like to explicitly state that actions are caused by particular events   If possible create an image representation of a solution

User · Accepted Answer

If else condition  also called alternatives in UML terms can indeed be represented in sequence diagrams  Here is a link where you can find some nice resources on the subject http   www ibm com developerworks rational library 3101 html

User · Answer

Very simple   using Alt fragment  Lets take an example of sequence diagram for an ATM machine Let s say here you want   IF card inserted is valid then prompt  Enter Pin     ELSE prompt  Invalid Pin   Then here is the sequence diagram for the same    Hope this helps

User · Answer

In Visual Studio UML sequence this can also be described as fragments which is nicely documented here  https   msdn microsoft com en-us library dd465153 aspx

User · Answer

If you paste  A do       if  condition1       X doSomething     else if  condition2       Y doSomethingElse     else      donotDoAnything         onto https   www zenuml com  It will generate a diagram for you

[uml] How to show "if" condition on a sequence diagram?

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