What's Become of UDDI and the Service Registry?

Two years ago UDDI v3.0 has been ratified as OASIS Standard. There are only a few vendors who offer serious Service Registry products and the main players have kept quiet for a long time. Many have blogged over the death of UDDI and the community seems to have lost interest in the Service Registry vision. Today as SOA Governance has become a major topic of interest, Service Registries are about to enter the scene, again.

According to Anne Thomas Manes, Research Director with Burton Group, who has been interviewed on 'The Registry and SOA Governance Market Landscape' report recently, the lack of Registry adoption has been an evolutionary issue:

That's because UDDI was part of the management space. You never need management right at the start. At the beginning you need the development tools. [...] You don't have to do management until you have systems that are running in production.

The report compares the leading Service Registry products such as Systinet Registry (HP), Infravio (webMethods), CentraSite (Software AG & Fujitsu) and IBM’s WebSphere Registry and Repository.

In a discussion thread following her interview, Manes elaborates on her perspective of service registries, service repositories, and the role of UDDI:

Traditionally, a registry has been supplied as part of the application platform, but I think that's the wrong perspective to take. A registry and/or repository should not be tightly associated with a single platform -- your goal is to get everyone in the company to use it to enable collaboration regardless of the platform they use to build systems. Repository supports development, and then also plays an important role in change control. Registry's role comes into play at the point you stage a service from development into production, during the configuration and provisioning processes.

She states that the key to a successful Registry is to offer more than a mere “bare bones implantation of UDDI version 3”. It has to provide strong search facilities, “open content model, automatic detection of relationships, [and] hyperlinks.

The UDDI protocol (nor its data model) was never intended to directly support human interaction. Both were designed to support programmatic interaction. (The protocol is a set of APIs, after all.) UDDI.org always envisioned that folks would build much more interesting UIs for humans.

The Systinet Registry seems to have won the comparison, at least concerning the feature set and its intuitive UI. Manes also thinks that it is

[…] the combination of search and REST (rather than REST by itself) that really sets Systinet apart. Systinet's search system is based on XQuery. (Also a unique feature.) It provides a Google like free-form search bar, which it then converts to an XQuery expression, and it provides an advanced search dialog screen that gives users the ability to specify more specific search criteria, which again gets converted to an XQuery expression. A user can save an XQuery expression in the repository -- it becomes a managed artifact just like any other artifact in the repository. And because it's REST, it also gets a URL. And you can reissue the query any time by performing a GET on the URL. And you can hyperlink to it. And you can set it up as an RSS feed. And you can apply a stylesheet to it for rendering in a portlet. And all kinds of other things. XQuery is what gives the repository a powerful search capability. REST is what enables users to more readily exploit the search capability.

In contrast to the other products IBM's WebSphere Registry and Repository introduces a completely new API, other than UDDI or ebXML. When asked about the pros and cons of each API, Anne Thomas Manes responds:

The problem is this: if I use AmberPoint for management, and I have Sonic ESB, and I have the Reactivity XML Gateway, and I'm still building services with WebSphere and .NET and Ruby on Rails, how do all those systems communicate with IBM's registry? It doesn't work. If I throw in the Systinet registry or the Infravio registry they all know how to talk to UDDI. They can all share the information. [Concerning ebXML] I don't think there's an issue at all. There's a spec out there called ebXML Registry, but nobody's using it.

Farrukh Najmi could not disagree more and gave a passionate answer to Manes’s dismissal of ebXML as a serious competitor to UDDI. He points out the following facts about ebXML (among others):

• ebXML Registry is not just "a spec out there". It is an approved ISO Standard. UDDI is not an ISO standard.
• ebXML Registry is being used by major governments such as US, Canada, Spain, Norway. In US it is powering the Department of Defense metadata registry as well as being used in Internal Revenue Service and Department of Education.
• ebXML Registry is being used by major world institutions like United Nations.
• ebXML Registry has been adopted by entire vertical such as IHE and HL7 in healthcare, OGC in GIS, SDMX in statistics, GS1 (formerly RosettaNet) in supply chain.

Paul Downey, Chief Web Services Architect with BT, joins in clearly stating his objections regarding a centralized repository and/or registry:

I periodically get to attend meetings where someone has a vision which involves a single registry/repository to rule them all. There follows a list of all the great metadata which this single truth will "own". Usually a can't hear what they're saying due to the sound of "Darth Vader's Theme" trumpeting in my lugholes. Empire building.. Empire building ..