OASIS Open

OASIS Web Services Discovery and Web Services Devices Profile (WS-DD) Technical Committee

The purpose of the Web Services Discovery and Web Services Devices Profile (WS-DD) Technical Committee (TC) is to define:

• A lightweight dynamic discovery protocol to locate web services that composes with other Web service specifications.
• A binding of SOAP to UDP (User Datagram Protocol) [1], including message patterns, addressing requirements, and security considerations.
• A profile of Web Services protocols consisting of a minimal set of implementation constraints to enable secure Web service messaging, discovery, description, and eventing on resource-constrained endpoints.

The TC will accomplish this purpose through continued refinement of Web Services Discovery (WS-Discovery) specification [2], SOAP-over-UDP specification [3], and Devices Profile for Web Services (DPWS) specification [4] submitted to the TC as referenced in this charter.

The TC will accept as input:

• WS-Discovery [2].
• SOAP-over-UDP [3].
• DPWS [4].

Other contributions will be accepted for consideration without any prejudice or restrictions and evaluated based on technical merit in so far as they conform to this charter.

The scope of the TC's work includes further refinement and finalization of the input WS-Discovery specification [2] to produce a standard version of the specification, including WSDL documents and XML schema renderings, which enables dynamic discovery of web services. This includes:

• A mechanism to:
  • Announce the arrival into a network (Hello message).
  • Announce departure from a network (Bye message).
  • Probe a network for matching services (Probe and ProbeMatch messages) where the match criteria for locating services is limited to the type of the service, the binding used by the service, and the administrative scope URIs assigned to the service.
  • Resolve an endpoint address to a transport address (Resolve and ResolveMatch messages).
• Support for the above mechanism in ad hoc networks (based on SOAP-over-UDP) and managed networks (based on SOAP-over-HTTP).
• Assignment of IP address and port used for discovery in ad hoc networks.
• Multicast suppression using discovery proxy in managed networks.
• Support for UDP (based on SOAP-over-UDP) and HTTP (based on SOAP-over-HTTP) transports.
• Guidance on use of endpoint addresses.
• An optional security model:
  • Securing multicast messages sent on ad hoc networks over UDP transport using compact signature format (based on WS-Security).
• Guidance on security considerations:
  • Securing messages sent on managed networks over HTTP transport (HTTPS based transport level security and WS-Security based message level security).
• A mechanism to order messages based on the order in which messages are transmitted from a service instance.
• XML Schema and WSDL to describe the following discovery protocol messages:
  • One-way Hello and Bye announcement operations.
  • One-way Probe, ProbeMatch, Resolve, and ResolveMatch operations for use in ad hoc networks.
  • Request-response operations to handle Probe, ProbeMatch, Resolve, and ResolveMatch messages for discovery proxy interactions in managed networks.
• Extensibility of Hello, Bye, Probe, ProbeMatch, Resolve, and ResolveMatch messages.
• Extensibility of scope matching algorithms.

The scope of the TC's work includes further refinement and finalization of the input SOAP-over-UDP specification [3] to produce a standard version of the specification that provides a SOAP binding to UDP. This includes:

• Details of the UDP packet carrying the payload (SOAP envelope) including its header.
• Definition of the following message exchange patterns (MEPs):
  • Unicast one-way.
  • Multicast one-way.
  • Unicast request, unicast response.
  • Multicast request, unicast response.
• Rules for multicast, retransmission, and message encoding.
• Guidance on security considerations (based on WS-Security).

The scope of the TC's work includes further refinement and finalization of the input DPWS specification [4] to produce a standard version of the profile specification, including XML schema renderings, which promotes both interoperability between resource-constrained Web service implementations and interoperability with more flexible client implementations using a core set of Web service specifications in the following areas:

• Sending messages to and from a Web service (based on SOAP, WS-Addressing) using UDP and HTTP transports.
• Dynamically discovering a Web service (based on WS-Discovery).
• Describing a Web service (based on WSDL, WS-Policy, WS-MetadataExchange, WS-Transfer, and XML Schema).
• Subscribing to and receiving events from a Web service (based on WS-Eventing), including description of event notifications in WSDL.
• Use of HTTPS in conjunction with compact signature security mechanism defined in WS-Discovery.
• Optional security mechanism (using HTTPS based transport level security and WS-Security).
  • Support for X.509 certificates.

WS-Discovery and SOAP-over-UDP specifications shall remain general, and broadly applicable, to device, enterprise, and other relevant usage scenarios.

WS-Discovery, SOAP-over-UDP, and DPWS specifications will uphold the basic principles of other Web services specifications of independence and composition and must be composable with the other specifications in the Web services architecture such as, but not limited to, HTTP 1.1 [5], SOAP 1.2 [6], SOAP-over-HTTP binding [7], WS-Addressing [8], WSDL 1.1 [9], WSDL Binding for SOAP 1.2 [10], WS-Eventing [11], WS-MetadataExchange [12], WS-Policy [13], WS-PolicyAttachment [14], WS-Security [15], WS-Transfer [16], XML Schema [17][18], WS-SecureConversation [19], and WS-Trust [20], AES/TLS [21], SHA1 [22], TLS [23], and X.509 v3 [24].

If any specification to be referenced by DPWS, WS-Discovery, or SOAP-over-UDP is outside of a standardization process at the time this TC moves to ratify the profile, or is not far enough along in the standardization process, any normative references to it in the TC output will be expressed in an abstract manner, and the incarnation will be left at that time as an exercise in interoperability.

While enabling composition with other specifications is a goal of the TC, it is also a goal to leave the specifics of how that composition is achieved outside the scope of the DPWS, WS-Discovery, and SOAP-over-UDP specifications.

This TC may produce the following non-normative supporting documents for WS-Discovery, SOAP-over-UDP and DPWS specifications:

• Primer or white paper describing usage scenarios and best practices.
• Interoperation test scenarios.

Out of Scope

The following is a non-exhaustive list provided only for the sake of clarity. If some function, mechanism or feature is not mentioned here, and it is not mentioned as in-scope in the Scope of Work section either, then it will be deemed to be out of scope.

The TC will not define a mapping of the functions and elements described in the specifications to any programming language or particular messaging middleware.

Except for the elements directly related to the functions in the scope of the specifications, the TC will not prescribe the format of messages that are transferred according to the specifications.

Where required, these functions are achieved by composition with other Web services specifications. The TC will not attempt to define functionality duplicating that of a specification normatively referenced in the input specification.

This TC will not specify changes to specifications, including but not limited to the referenced specifications, external to the input DPWS, WS-Discovery, and SOAP-over-UDP specifications.

This TC may produce the following non-normative supporting documents for WS-Discovery, SOAP-over-UDP and DPWS specifications:

• WS-Discovery version 1.1 specification.
• SOAP-over-UDP version 1.1 specification.
• DPWS version 1.1 specification.
• Non-normative supporting documents for WS-Discovery, SOAP-over-UDP and DPWS specifications:
  • Primer or white paper describing usage scenarios and best practices.
  • Interoperation test scenarios.

For clarity, the out of scope features include, but are not limited to, the following:

• Support for SOAP 1.1.
• Support for WSDL 2.0.
• Mechanisms for provisioning or deployment, or guidance on provisioning or deployment technologies, either by inclusion or reference.
• Use or definition of mechanisms or protocols, other than those defined or used in the input specifications, such as:
  • Additional addressing mechanisms.
  • Additional discovery protocols.
  • Additional match criteria while probing the network for matching services.
  • Paging mechanisms for discovering services during discovery proxy interactions.
  • Discovery proxy implementation details such as caching and data handling techniques.
  • Additional device description languages or protocols for obtaining descriptions from implementations.
  • Additional eventing protocols.
  • Additional metadata exchange or transfer mechanisms.
  • Additional security algorithms or mechanisms.
  • Support for security certificates other than X.509.
  • Support for additional transport protocols other than UDP and HTTP.
• Descriptions for any particular device or service types.
• Message formats or mechanisms other than SOAP messages.
• Features, mechanisms, extension points, or optimizations beyond those defined in the input specifications [2] [3] [4] are out of scope, unless included as in scope.

Constraining WS-Discovery and SOAP-over-UDP specifications to specific usage scenarios, such as use only with devices, is disallowed.

This TC has the following set of deliverables:

• WS-Discovery version 1.1 specification.
• SOAP-over-UDP version 1.1 specification.
• DPWS version 1.1 specification.

This TC shall produce a Committee Specification version of Devices Profile for Web Services, WS-Discovery, and SOAP-over-UDP specifications by March 2009. Work on these specifications will proceed in parallel. The standard version of these specifications will reflect refinements, corrections or material technological improvements with respect to the input specifications and in accordance with this charter.

Following approval of Devices Profile for Web Services Version 1.1, WS-Discovery Version 1.1, and SOAP-over-UDP Version 1.1 specifications as OASIS standards, the TC will enter an extended maintenance period during which it may adopt Approved Errata for DPWS, WS-Discovery, or  SOAP-over-UDP in accordance with the OASIS Technical Committee  Process. The maintenance period will continue until the TC is Closed in accordance with Section 2.15 of the OASIS Technical Committee Process. During the maintenance period, in addition to any Approved  Errata that may be adopted, the TC will deliver updated DPWS, WS-Discovery, or SOAP-over-UDP specifications, or any combination thereof, as revised OASIS standards, to address the following, if required:

1. Update the references in DPWS to WS-Eventing, WS-MetadataExchange, and WS-Transfer specifications to reference the W3C Recommendation version of those specifications, and profile those specifications as necessary to accommodate changes included in them;
2. Update the reference in DPWS to WS-I Basic Profile Version 1.1 specification to reference the WS-I Basic Profile 2.0 specification, if that specification is approved in WS-I prior to or at approximately the same time as approval of the relevant W3C Recommendations produced by the W3C WS-ResourceAccess Working Group;
3. Incorporate Substantive Changes resulting from (a) reconsideration of technical issues originally introduced to the TC prior to approval of Version 1.1 of DPWS, WS-Discovery, and SOAP-over-UDP specifications but deferred for later consideration, (b) resolution of specification ambiguities or flaws identified through implementation experience or interoperability testing of elements of Version 1.1 of DPWS, WS-Discovery, and SOAP-over-UDP specifications; and (c) further  specification profiling, clarification, and enhancing of security in DPWS identified through implementation experience or interoperability testing; and,
4. Incorporate previous Approved Errata and other corrections, clarifications and editorial changes that are not Substantive Changes.

This TC will operate under the "RF (Royalty Free) on RAND Terms" IPR mode as defined in the OASIS Intellectual Property Rights (IPR) Policy, effective 15 April 2005.

The anticipated audience for this work includes:

• Web services platform vendors, service repository providers, application middleware vendors.
• System integrators, value-added resellers, and end users implementing Web services-based solutions that require an interoperable, composable distributed device control solution.
• End users implementing Web services-based solutions and vendors offering Web services products that require an interoperable, composable, dynamic discovery mechanism and SOAP-over-UDP transport binding.
• Device manufacturers (printers, scanners, projectors, medical devices, energy management devices, media devices, and many others).
• Device controller manufacturers (computers and computer software, handheld computers, cellular telephones, handheld remote controls, and many other devices) that make use of devices conforming to the DPWS profile.
• Specification authors working on WSDLs defining the characteristics of specific device types.
• Software architects and programmers, who design, write, test, or integrate applications for Web services and devices whose interactions are based on Web services.

TC business will be conducted in English.