The arguments for the adoption of WSDL v2.0 were primarily based on its areas of enhanced functionality. Of these, the ones of possible importance to SIF were:
- Support for additional message patterns (ex: “Out – Multi In” could correspond to Register for Events, Receive 0-n Events)
- Better and more powerful fault handling notation, allowing clearer and easier reuse of WSDL segments within the WSDL file.
- Improved SOAP v1.2 bindings which default many formerly explicit parameters to reduce the likelihood of interoperability problems.
- Support for interface inheritance
All of these would bring increased clarity and structure to any v2.0 WSDLs SIF might publish. In addition, since WSDL 2.0 migration is difficult (when a service updates to WSDL 2.0, all client stubs must be upgraded at that time), then if a normative WSDL v2.0 dependency were to eventually be decided on for SIF, it would make great sense to do so at the beginning.
The arguments against the adoption of WSDL v2.0 included the following (of which the first was considered the decider).
- WSDL 2.0 is not supported by most Java and .NET based developer toolkits (Apache being a notable exception)
- WSDL 2.0 had gained little industry traction in the 3 years since the specification was formally approved. What little WSDL 2.0 adoption there is, is currently centered around REST and not SOAP.
- All comparable industry standards in the Education space utilize WSDL v1.1
The Zone WSDLs for the SIF v2.5 release are provided in WSDL 1.1 only, and that is the only version the ZIS is required to support.