This is great. My (so far, only) experience with SOAP started when my boss asking me to investigate the new version of a (very big) vendor's SOAP API. Support for the old version of the API was being dropped in a few days.

It turns out that our framework has SOAP built in, so I had it suck in the WSDL and make a sample request. It was rejected with a generic error. As it turns out, our framework was generating requests that looked like this (simplified with much SOAP nonsense stripped out):

  <SOAP-ENV:Envelope>
    <Authenticate xmlns="http://bigcorp.example.com/elements/global">…</Authenticate>
  </SOAP-ENV:Envelope>

…and the requests in the API documentation look like this:

  <SOAP-ENV:Envelope xmlns:bigcorp="http://bigcorp.example.com/elements/global">
    <bigcorp:Authenticate>…</bigcorp:Authenticate>
  </SOAP-ENV:Envelope>

the difference being that our framework declares a "default namespace", while their API expected a "namespace prefix". As far as I could tell from reading the spec (always a bad sign when you're using a standard that both ends support) the difference shouldn't matter.

- - -

I went to my boss. He showed me the old code; all the requests it needs to make are hardcoded based on the docs, and substitute XML-encoded variables in the right places.

Save a few minor changes, that's the process we still use today, and it fucking works.