"Related Work" statements for WS-DD specifications

[Toby Nixon <Toby.Nixon@microsoft.com>]

I was asked to split the single Related Work statement from the original WS-DD charter into separate statements for DPWS, WS-Discovery, and SOAP-over-UDP (Action Item #126). It turned out to be a bit more of a job than I had anticipated! Here are proposed statements for your consideration and approval.

 

            -- Toby

 

DPWS

 

There is no other known standardization work that exists or is currently in progress to apply Web services specifications to resource-constrained devices. The Mobile Web Initiative of W3C (http://www.w3.org/Mobile/) is focused on web browsing from mobile devices as opposed to controlling mobile devices using Web services or allowing mobile devices to control others using Web services. The OASIS Remote Control XML TC (http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=remote-control) is focused on development of a small set of specific operations for remote control of devices which are expressed in XML but without the full richness of the entire Web services protocol suite. There has been work on devices that communicate over IP based on different protocols, such as UPnP (http://www.upnp.org/specs/arch/UPnP-arch-DeviceArchitecture-v1.0.pdf) and IGRS (http://www.igrs.org); UPnP was submitted to ISO/IEC JTC1 as a Publicly Available Specification and has been approved as an international standard (ISO/IEC 29341), and work on IGRS is in progress in ISO/IEC JTC1 SC25 (expected to become ISO/IEC 14534-4). However, neither of these protocols is as broadly-based on Web services specifications as DPWS; they do not incorporate the richness, interoperability, security, scalability, and composability of the full Web services protocol suite. DPWS is based on protocols in the Web services architecture, works well with other specifications within that architecture, and composes with other specifications in the Web services architecture such as, but not limited to, IP, TCP, HTTP, SOAP, XML, XML Schema, WSDL, WS-Addressing, WS-Policy, WS-PolicyAttachment, WS-Discovery, SOAP-over-UDP, WS-Transfer, WS-MetadataExchange, WS-Eventing, WS-Security, WS-SecureConversation, WS-Trust, AES/TLS, SHA1, TLS, and X.509. WS-Eventing, WS-MetadataExchange, and WS-Transfer have been submitted to W3C for standardization through the WS-ResourceAccess Working Group; the OASIS WS-DD TC anticipates updating DPWS in the future to reference the standardized versions of these specifications.

 

WS-Discovery

 

A number of protocols have been defined for discovery of services on IP networks, including IETF Service Location Protocol (http://tools.ietf.org/html/rfc2608), UPnP Simple Service Discovery Protocol (http://www.upnp.org/specs/arch/UPnP-arch-DeviceArchitecture-v1.0.pdf) also standardized as ISO/IEC 29341-1 Section 1, DNS Service Discovery (http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt), and OASIS Universal Description, Discovery and Integration (http://www.oasis-open.org/committees/uddi-spec/doc/tcspecs.htm). SLP, SSDP, and DNS-SD support discovery of services in unmanaged ad hoc network scenarios. UDDI was not designed with ad hoc scenarios in mind; it is based on a service registry that is usually maintained at a known network location. However, UDDI is the only one of these existing protocols that is based on Web services protocols and architecture. WS-Discovery supports both ad hoc and managed scenarios, as well as being based on Web services protocols and architecture, including, but not limited to IP, UDP, TCP, HTTP, SOAP, XML, XML Schema, WSDL, WS-Addressing, WS-Security, and XML-Signature. WS-Discovery uses SOAP-over-UDP for multicast announcements in ad hoc networks. It is lightweight for both service providers and consumers, and will work well on a bandwidth-constrained network. Because it was written with other WS-* protocols in mind, WS-Discovery composes well with them. WS-Discovery was developed in conjunction with Devices Profile for Web Services (DPWS), but is not limited to use only in lightweight device scenarios.

 

SOAP-over-UDP

 

Many application protocol patterns match the semantics of the User Datagram Protocol (http://tools.ietf.org/html/rfc768); some do not require the delivery guarantees of TCP, while others make use of multicast transmission. In order to allow Web services to support these patterns, a way is needed to map SOAP envelopes to user datagrams. This support is essential for services using WS-Discovery, where the use of multicast and need for low connection overhead makes UDP a natural choice; it is anticipated that other protocols will have similar requirements. SOAP-over-UDP is based on Web services protocols and architecture, including, but not limited to IP, UDP, SOAP, XML, WS-Addressing, and WS-Security. UPnP defines a mechanism for transport of HTTP-like messages over UDP as part of its Simple Service Discovery Protocol (http://www.upnp.org/specs/arch/UPnP-arch-DeviceArchitecture-v1.0.pdf, Section 1) and a similar mechanism is used in IGRS (http://www.igrs.org), but no known existing specification defines transport of SOAP messages over UDP, and there is no known similar work in progress in OASIS or any other organization.

 

 

Toby Nixon  |  Senior Standards Program Manager  |  Windows Device and Storage Technologies  |  Microsoft Corporation

toby.nixon@microsoft.com  |  www.microsoft.com | V: +1 425 706 2792  |  M: +1 206 790 6377  |  F: +1 425 708 4811