For SOAP server you could have a look at the "besimple/soap-server" package, available through composer.
Can't find an easy way to do WSDL generation, the besimple Symphony bundle has it from the looks of it, but I'm not sure how easy it will be to port it.
I second this, as I've needed to result to using cURL and couldn't get an abstraction layer created for nuSoap.
I integrate with about 30 different systems, more than half of them are still SOAP-based, it's like assuming you don't need to code for IE7 any longer even though the reality is a large number of people still use it.