PHP, SOAP and operation signatures
After investigating SOAP further there seems to be a common confusion regarding the difference between rpc/literal and document/literal and how it is handled in PHP. There is even a bug 49169 reported because PHP ext/soap maps all operations defined in the web service with the same signature to the first defined function or method in PHP when using document/literal style.
It is not a bug. The style document/literal is for sending messages with document data. It is not a remote procedure call. For that we have rpc/literal. So if you look at it that way it is completely understandable that only one method should be around to handle one specific type of message (document).
It is also completely correct behaviour according to the specification WS-I Basic Profile.
“In the case of rpc-literal binding, the operation name is used as a wrapper for the part accessors. In the document-literal case, since a wrapper with the operation name is not present, the message signatures must be correctly designed so that they meet this requirement.“
As document/literal is the preferred style, and some implementations obviously have a tendency to dislike rpc/literal, a lot of people is going down the document/literal route without understanding the implications and what the real difference really is.
I don’t think this should stop ext/soap in PHP to use the soapAction header for routing when necessary. According to WSDL 1.1 the soapAction attribute is mandatory when HTTP protocol binding is used. Whether rpc/literal or dcoument/literal style is used is of no difference. So is this information just garbage for document style messages?
Anyways, PHP bug 46169 is to my understanding not really a bug. But it is a reasonable feature request.
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I just want to point to the “Document/literal wrapped” pattern, where the root element in the document specifies the operation name. This is a pattern used by Microsoft, e.g. for .NET services.
For a good reference about SOAP structures see:
http://www.ibm.com/developerworks/webservices/library/ws-whichwsdl/
SOAP is a big, undocumented mess for PHP (YMMV). We ended up using WSO2 WSF framework for talking with the .NET soap server (which had its drawbacks, too, like no possibility to define timeouts etc.) and constructed our XML documents for “Document/literal wrapped” by ourselves with SimpleXML.