title: When to destroy in a sequence diagram
body: <p>I can't actually find a clear answer for this. In a lot of online design tools (e.g. <a href="http://www.websequencediagrams.com/" rel="nofollow">Web Sequence Diagrams</a>), there is an option to "activate" and "deactivate" a process, whilst there is a separate action to "destroy" the process. When is this used?</p>
  
  <p>If in the diagram I am modelling I am connecting to an online stream, when I am done with it do I deactivate it or destroy it? When I use an application and it is finished, do I deactivate it or destroy it?</p>