SOAP was actually pretty easy to use, once it settled out.

For the most part, everyone used some kind of SDK that translated WSDL (Web Services Description Language) specifications to their chosen language.

So you could define almost any function - like PostBlog(Blog blog), and then publish it as a WSDL interface to be consumed by a client. We could have a Java server, with a C# client, and it more or less just worked.

We used it with things like signatures, so the data in the message wasn't tampered with.

Why did it stop getting popular? It probably really started to fall out of favor when Java/C# stopped being some of the more popular programming languages for web development, and PHP and Ruby got a lot more momentum.

The idea was that REST/JSON interfaces would be easier to understand, as we would have a hypermedia interface. There was sort of an attempt to make a RESTy interface work with XML, called WebDAV, that Microsoft Office supported for a while, but it was pretty hard to work with.

I've got some old SOAP code from 2001 here at the bottom of this article:

https://www.infoworld.com/article/2160672/build-portals-with...