All things related to Messaging and Application Services.
Examples are Messaging Patterns, Message Queuing Architectures, Message Oriented Middleware.
Also include implementations such as Internet Inter Orb Protocol, Simple Object Access Protocol, and products such as Microsoft Indigo.
Underutilised but important category? Delete When Cooked
I suggest all pages with Soap, Rest (Rest Architectural Style), etc should be tagged with this category.
And yes I have seen Please Please Dont Categorize Every Page On Wiki, but I think this is a very important category.
prompted by seeing the page Jabber And Soap without appropriate categories at all
Changed mind. I have created Category Web Services (itself being category as CategoryMessagingServices) instead.
See original on c2.com 