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InfoQ Homepage News WS-Discovery and WS-DeviceProfile Public Review

WS-Discovery and WS-DeviceProfile Public Review

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We've discussed a number of WS-* standards and specifications over the years but ones that haven't come up before are WS-Discovery and WS-DiscoveryProfile, which went for OASIS standardization in late 2008. As the FAQ for the technical committee states:

This technical committee aims to standardize the WS-Discovery, SOAP-over-UDP and Devices Profile for Web Services (DPWS) specifications. [...] At a high level the purpose of the TC is to standardize an interoperable way to discover Web services, be they enterprise services or embedded in devices, in an ad-hoc network or a carefully managed and controlled network. The other major goal of the TC is to define a lightweight, interoperable profile of Web services standards for communicating with Web services embedded in devices such as printers, scanners, conference room projectors, and many others.

Despite its relatively low-key venture into the field of WS-* compared to some other standards/specifications, WS-Discovery has certainly been seeing a fair bit of interest over the years. As Jesus Rodriguez says when talking about its inclusion within WCF:

Contrary to other WS-* protocols, WS-Discovery has found a great adoption among the network device builders as it allows to streamline the interactions between these type of devices. For instance, a printer can use WS-Discovery to announce its presence on a network so that it can be discovered by the different applications that require printing documents. Windows Vista's contact location system is another example of a technology based on WS-Discovery.

The technical committee includes the usual list of suspects, such as IBM, MSFT, CA and Red Hat. No Oracle or Sun this time. However, recently the technical committee agreed to push the current drafts into a public review period, where anyone can pass comment or ask questions. The specifications are:

As William Vambenepe (Oracle) says:

This trio has been swirling around for many years. Mostly in the USB/PnP/UPnP community (devices physically attached to Windows boxes) but they have popped up on the enterprise WS-* radar screen from time to time, for two reasons:
  • WS-DD as another specification (in addition to WS-Management and the later incarnations of WS-MeX) who uses WS-Transfer, and therefore as a (poor, in my view) justification for making it a stand-along specification
  • WS-Discovery as potentially useful for datacenter management (for resource discovery, obviously)

William looks at the member list and posits that many of them are interested in the potential datacenter-related applications of the standards being developed.

Well, I guess Novell and RedHat could be in the game from the perspective of plugging devices into desktops running their version of Linux rather than from a datacenter perspective. CA and IBM could be in it from an Asset Management (for devices) perspective too. [...] In any case, no Apple, Palm, RIM, Google (Android) or Sun (JavaFX). I guess handheld devices aren’t the devices targeted here. Rather it’s more printers and cameras. In which case you have to wonder why HP isn’t there [...].

He isn't sure if WS-Discovery has any role to play in the datacentre, pointing out that although that environment is becoming more dynamic it's typically at the level of "guest VM (creation of new instances) and above (applications, services…)", where their creation will most probably be orchestrated anyway (services rarely just "pop" into existence like particle/anti-particle pairs, after all), thus removing the need for resource-initiated discovery mechanisms. So as he concludes:

Which leaves the physical equipment. Do we need WS-Discovery to get from the point of a server being plugged to the point where it has been provisioned? There are alternatives in this somewhat homogenous environment. And UDP multicast only takes you so far in a datacenter (at lest without extensions). So my guess is no. But who knows. The drafts are here for you to review if you think it may be relevant.

At the moment it does seem like Microsoft is doing the majority of the work around this standardization effort. So one way or another WS-Discovery is likely to make its way into a desktop near you at the very least. Whether it goes further will depend on other factors of course.

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