Is soap really interoperable?

I have read this question here: Consuming a PHP SOAP WebService with ASP.NET开发者_开发知识库

So does SOAP really hold his promise of Interoperability ?

Yes, absolutely; it's just that old and/or crappy implementations of it have given it a bad reputation. Too many SOAP implementations out there are "very nearly" SOAP compliant, but "very nearly" is no good.

Modern SOAP stacks (e.g. WCF, JAX-WS) make a much better job of it.

Yes^

^Assuming that everyone supports/implements/follows the protocol correctly. That is, it is no different than any other data-exchange/data-format or protocol.

Yes

Have used it on several projects. Indispensable when integrating with 3rd party vendors.

On the client side, I recommend using SOAPUI for testing the service (interoperability can take more time at the config layer)

Once you are confident in the service definitions, then you can also use Apache Axis to auto-generate your classes.

For simple SOAP requests, you can also use straight up http requests and and XML parsing. (In JAva this is easy enough with javax.xml)