Seq Diagram Drawing try catch block in UML
UML sequence diagram lacks of being able to visualize exceptions. There are "workarounds" however, please refer to:
- Break
- Sequence Diagrams: Questions & Answers
- Stackoverflow answer
There is no standard way to model exception handling in a sequence diagram. Here is how I handle it:
The above diagram is generated with Web Sequence a free (open source) chrome extension. You can get it from here: https://chrome.google.com/webstore/detail/web-sequence/kcpganeflmhffnlofpdmcjklmdpbbmef or from the official site: https://www.zenuml.com . To test it out, you can simply paste the following code into the code editor of the above plugin or on the site.
JobTask.Run() {
try() {
Action.Execute() {
InternalException.throw()
}
}
InternalException.Catch() {
Logger.Error()
HighLevelException.throw()
}
}
It demonstrates that we have a try block. Within this block, we execute Action.Execute() in which InternalException could be thrown. Then we catch it, log an error and rethrow a HighLevelException, which is a quite typical exception handling strategy.