Sonic Connect : How to validate a request from the WSDL

I've exposed a process as a Webservice.

I would like to validate some attribute values in a xsd defined in the WSDL.

For example :

     request extract :

          <trac:environment trac:type="test" />

                    where environment should only be : "test", "accptance" or "production".

     wsdl extract :

          ....

          <xs:complexType name="environmentType">

               <xsd:attribute name="type">

                    <xs:annotation>

                         <xs:documentation>

                              defini le type d'environnement pour lequel la trace est emise (test,

                              acceptance ou production)

                         </xs:documentation>

                    </xs:annotation>

                    <xs:restriction base="xs:string">

                         <xs:enumeration value="production"/>

                         <xs:enumeration value="acceptance"/>

                         <xs:enumeration value="test"/>

                     </xs:restriction>

               </xsd:attribute>

                   ....

How can I do that ?

Thanks