From: "Oliver M. Bolzer" <oliver@...>
Date: 2003-11-11T23:14:39+09:00
Subject: WSDL: Only one fault per operation?

Hi!

I'm currently building a simple request-response style webservice using
SOAP4R and describing it in WSDL, so that it can easily be used from multiple
langages.

I was wondering how best I should describe the exceptions my methods will be
raising. First, I defined two compexType's that look like what SOAP4R actually
throws.

<wsdl:types>
  <xsd:schema xmlns="http://www.w3.org/2001/XMLSchema"
      targetNamespace="http://fakeroot.net/webservice/rbg/ver1/">
    <complexType name="AuthenticationError">
      <all>
        <element name="message" type="xsd:string" />
        <element name="backtrace" type="xoapenc:Array" />
      </all>
    </complexType>
    <complexType name="AuthorizationError">
      <all>
        <element name="message" type="xsd:string" />
        <element name="backtrace" type="xoapenc:Array" />
      </all>
    </complexType>
  </xsd:schema>
</wsdl:types>

and then, defined each of them as a message.

<wsdl:message name="authentication_ERROR" >
  <wsdl:part name="exception" type="tns:AuthenticationError" />
</wsdl:message>
<wsdl:message name="authorization_ERROR" >
  <wsdl:part name="exception" type="tns:AuthorizationError" />
</wsdl:message>

Finally I bound the two messages to my operation with the <fault/> element
<wsdl:portType name="FooService">
  <wsdl:operation name="dosomething">
    <wsdl:input message="tns:dosomething_IN" />
    <wsdl:output message="tns:dosomething_OUT" />
    <wsdl:fault message="tns:authentication_ERROR" />
    <wsdl:fault message="tns:authorization_ERROR" />
  </wsdl:operation>
</wsdl:portType>


The AuthenticationError and AuthorizationError classdefs are generated according
to the type-definition (naturally, similart to Ruby's Exception class) but
using the XML-code above, only AuthorizationError inherits from StandardError,
AuthenticationError doesn't. If I swap the two <fault> tags above, only
AuthorizationError inherits but AuthenticationError doesn't.

Looking at SOAP4R 1.5.0's wsdl/operation.rb, it seems that it only supports
one fault per operation, overriding earlier <fault>s with later occuring ones
in WSDL::Operation#parse_element().
But the WSDL 1.1 schema states that an <operation> can have multiple <faults>.

...
<element name="operation" type="wsdl:operationType"/>
<complexType name="operationType">
....
  <element ref="wsdl:fault" minOccurs="0" maxOccurs="unbounded"/>
....
</complexType>


A bug in SOAP4R 1.5.0 ? Or I might be misunderstanding something.
Or is there any recommended/proper way to declare the exceptions that
my SOAP4R-service will raise in WSDL, in a langage-independent way ?

-- 
	Oliver M. Bolzer
	oliver@gol.com

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