Blogger: Richard Watson
Interoperability is one of the design principles that distinguish Web Services as service middleware from its forefathers: RPC and distributed object computing and from its uncle: message-oriented middleware.
Cross vendor interoperability has been one of my soap box issues (sic.) since I started in this industry, so I welcome anything that contributes to it. When I’ve made business cases for SOA investment, and advised clients doing the same, highlighting the benefits of quicker time to market and lower barriers to reaching new customers and partners always figured in my presentations to executives. But these benefits can only be realized and measured if interoperability is a given in the integration fabric. Very often, beyond the trivial use-cases, it is not.
Over the last couple of years there has been a trend toward vendors offering complete SOA suites, focusing on strong cohesion (real or imagined) at the suite level. In this model, there's less motivation for cross vendor interoperability and open integration. This trend exposes the dangers of going with a SOA suite: vendor lock-in; isolated, non-integrated components; and exposure to the risk of needing ongoing consulting services for bespoke integration. As vendor consolidation slows this year, but continues, infrastructure suites will continue to dominate and selecting products to populate a heterogeneous services infrastructure will remain difficult.
So I welcome the announcement of the Web Services Test Forum (WSTF), a vendor and end-user coalition set up to test Web Services interoperability scenarios. The approach is described in this essential post by Oracle’s Gilbert Pilz and another by Doug Davis from IBM.
This forum is an evolution in the interoperability story begun by the soapbuilders group I was a part of starting in 2001 while working for Cape Clear Software. This group of SOAP stack vendors and interested 3rd parties was created in 2001 – kicked off by this seemingly innocent email from Tony Hong. Credit goes to IBM and Microsoft for nurturing the idea with support. The work of soapbuilders was carried on by Web Services Protocol Workshops that Jorgen Thelin (my colleague back in Cape Clear days) ran at Microsoft.
We need ask ourselves, why is this group coming together now? Why has the prophecy not come true? Vendors are being beaten up (not enough, IMO) by end-users for their interop failings – so in one way it’s a “look, we are doing something” measure.
Also, how does this relate to the work of the Web Service Interoperability Organization (WS-I)? Is this an implicit sigh of desperation at the lack of progress at the WS-I? For example, it’s taken a long time to get the crucial Reliable Secure Profile out of that hopper.
On the WSTF announcement call, Burton Group’s Anne Thomas Manes asked why this effort is not driven through the WS-I. Steve Harris from Oracle explained that while WS-I is a consensus driven effort, WFTF brings a different approach to interoperability. Harris highlighted vendor collaboration and lowering the barriers to entry as differentiators. IBM's Karla Norsworthy added that WSTF is complementary to WS-I, a more lightweight approach, giving the example that the forum could easily bring a few vendors together to test a scenario. Many of the WSTF’s 15 members are also members of WS-I.
Will WSFT make a real contribution to interoperability?
I’m impressed and made hopeful by a number of things. Firstly, that membership obliges a vendor to support live endpoints for each scenario. This means that debate and negotiation will not be the deliverables of the forum; live test results, published on the internet will be. We can view testing between the implementations as a fully connected network, i.e., every endpoint is tested with every other, so each additional implementation adds considerably (as c=(n^2 – n) / 2 for you topology geeks) to the level of interoperability assurance.
Secondly, having end-users like Ford and AIAG in the forum is an important step. Sure, there are a small number of end-users right now, but the usefulness of this forum grows dramatically with the number of end-user enterprises participating. The forum process encourages end-users to submit requirements for the tested scenarios which usefully turns attention onto things other than wire formats.
At the first face-to-face soapbuilders session in 2001 we sat in a room on the IBM campus in Raleigh, with the code for our SOAP stacks on our weeny laptops and bashed out some basic interop scenarios. There was a real sense of making progress co-operatively at those sessions. If this spirit of co-operation and community amongst engineers can be fostered in the WSTF, leaving aside the commercial and competition issues, then there is an opportunity for real achievement.
Actually, the real question is whether the participants, especially the vendors, recognise this opportunity as a prisoner’s dilemma scenario? If everybody co-operates, everybody benefits.
A number of issues may limit the WSTF’s impact. Clearly, not having Microsoft as a member is a problem. While industry manoeuvres might keep analysts and vendors themselves amused, end-users couldn’t care less; they just want software to work. So having Microsoft involved is a core credibility issue for the WSTF. According to WSTF spokespeople, other members will be hosting Microsoft endpoints. That’s not quite the same thing. Microsoft are committed to WS-I and also to Apache Stonehenge which has similar aims to WSTF.
I think other web services approaches need to be included. To launch an initiative purely directed at Web Services in December 2008 looks antiquated, although the IBM and Oracle spokespeople did claim other approaches, like RESTful web services are not excluded in theory.
As with any community based activity, the only real measure of its success is its interactivity. Let’s give WSTF time and then count the live interoperable implementations and end-user organizations active in the forum.
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