Web Services Addressing provides transport-neutral mechanisms to address Web services
and messages. Web Services Addressing Core (this document) defines a set of abstract
properties and an XML Infoset [
This is the
In this Working Draft, the Web Services Addressing Working Group
has, in keeping with its
Discussion of this document takes place on the public public
This document was produced under the
Per
Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
Last Modified: $Date: 2004/12/08 21:29:45 $
Web Services Addressing (WS-Addressing) defines two constructs that convey information that is typically provided by transport protocols and messaging systems: endpoint references and message addressing properties. These constructs normalize this underlying information into a uniform format that can be processed independently of transport or application.
A Web service endpoint is a (referenceable) entity, processor, or resource to which Web service messages can be targeted. Endpoint references convey the information needed to identify/reference a Web service endpoint, and may be used in several different ways:
To convey the information needed to access a Web service endpoint
To provide addresses for individual messages sent to and from Web services
To deal with this last usage case this specification defines a family of message addressing properties that allows uniform addressing of messages independent of underlying transport. These message addressing properties convey end-to-end message characteristics including addressing for source and destination endpoints as well as message identity.
Both of these constructs are designed to be extensible and re-usable so that other specifications can build on and leverage endpoint references and message information headers.
The following example illustrates the use of these mechanisms in a SOAP 1.2 message being sent from http://business456.example/client1 to http://fabrikam123.example/Purchasing:
Lines (002) to (011) represent the header of the SOAP message where the mechanisms defined in the specification are used. The body is represented by lines (012) to (014).
Lines (003) to (010) contain the message information header blocks. Specifically, lines (003) to (005) specify the identifier for this message and lines (006) to (008) specify the endpoint to which replies to this message should be sent as an Endpoint Reference. Line (009) specifies the address URI of the ultimate receiver of this message. Line (010) specifies an Action URI identifying expected semantics.
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in RFC 2119 [
When describing abstract data models, this specification uses the notational
convention used by the XML Infoset [
When describing concrete XML schemas [
This specification uses a number of namespace prefixes throughout; they are
listed in
Prefix | Namespace |
---|---|
S | http://www.w3.org/2003/05/soap-envelope |
S11 | http://schemas.xmlsoap.org/soap/envelope |
wsa | http://www.w3.org/2004/12/addressing |
xs | http://www.w3.org/2001/XMLSchema |
WS-Addressing may be used with SOAP [
All information items defined by WS-Addressing are identified by the XML
namespace URI [
This section defines the information model and syntax of an endpoint reference.
This specification introduces the endpoint reference, a construct designed to support the following usage scenarios:
Dynamic generation and customization of service endpoint descriptions.
Identification and description of specific service instances that are created as the result of stateful interactions.
Flexible and dynamic exchange of endpoint information in tightly coupled environments where communicating parties share a set of common assumptions about specific policies or protocols that are used during the interaction.
An endpoint reference consists of the following abstract properties:
An address URI that identifies the endpoint. This may be a network address or a logical address.
A reference may contain a number of individual properties that are
required to identify the entity or resource being conveyed.
Reference identification properties are element information items
that are named by QName and are required to properly dispatch
messages at the endpoint. Reference properties are provided by the
issuer of the endpoint reference and are otherwise assumed to be
opaque to consuming applications. The interpretation of these
properties (as the use of the endpoint reference in general) is
dependent upon the protocol binding and data encoding used to
interact with the endpoint. Web Services Addressing - SOAP
Binding[
A reference may contain a number of individual parameters which are
associated with the endpoint to facilitate a particular interaction.
Reference parameters are element information items that are named by
QName and are required to properly interact with the endpoint.
Reference parameters are also provided by the issuer of the endpoint
reference and are otherwise assumed to be opaque to consuming
applications. The use of reference parameters is dependent upon the
protocol binding and data encoding used to interact with the
endpoint. Web Services Addressing - SOAP Binding[
The QName of the primary portType of the endpoint being conveyed, see
Web Services Addressing - WSDL Binding
The QName identifying the WSDL service element that contains the
definition of the endpoint being conveyed, see Web Services
Addressing - WSDL Binding
A reference may contain a number of policies that describe the behavior, requirements and capabilities of the endpoint. Policies may be included in an endpoint to facilitate easier processing by the consuming application, or because the policy was dynamically generated. However, embedded policies are not authoritative and may be stale or incoherent with the policies associated with the endpoint at the time when the interaction occurs.
This section defines an XML Infoset-based representation for an endpoint reference as both an XML type (wsa:EndpointReferenceType) and as an XML element (<wsa:EndpointReference>).
The wsa:EndpointReferenceType type is used wherever a Web service endpoint is referenced. The following describes the contents of this type:
The following describes the attributes and elements listed in the schema overview above:
This represents some element of type wsa:EndpointReferenceType. This example uses the predefined <wsa:EndpointReference> element, but any element of type wsa:EndpointReferenceType may be used.
This REQUIRED element (of type xs:anyURI) specifies the [address] property of the endpoint reference. This address may be a logical address or identifier for the service endpoint.
This OPTIONAL element contains the elements that convey the [reference properties] of the reference.
Each child element of ReferenceProperties represents an individual [reference property].
This OPTIONAL element contains the elements that convey the [reference parameters] of the reference.
Each child element of ReferenceParameters represents an individual [reference parameter].
This OPTIONAL element (of type xs:Qname) specifies the value of the
[selected port type] property of the endpoint reference, see Web
Services Addressing - WSDL Binding
This OPTIONAL element (of type xs:QName) specifies the
<wsdl:service> definition that contains a WSDL
description of the endpoint being referenced, see Web Services
Addressing - WSDL Binding
This OPTIONAL attribute (of type xs:NCName) specifies the name of the
<wsdl:port> definition that corresponds to the
endpoint being referenced, see Web Services Addressing - WSDL
Binding
This OPTIONAL element contains policies that are relevant to the interaction with the endpoint.
Each child element of Policies represents an individual [policy].
This is an extensibility mechanism to allow additional elements to be specified.
This is an extensibility mechanism to allow additional attributes to be specified.
The following shows an example endpoint reference. This element references the port of type "fabrikam:InventoryPortType" at the URI "http://www.fabrikam123.example/acct".
During the course of Web services interactions applications may receive multiple endpoint references describing the endpoints it needs to interact with. Different copies of an endpoint reference may also be received over time.
The following rules clarify the relation between the behaviors of the endpoints represented by two endpoint references with the same [address] and the same [reference properties].
The two endpoints accept the same sets of messages, and follow and require the same set of policies. That is, the XML Schema, WSDL, and policy metadata applicable to the two references are the same.
In particular, the policies applicable to the two endpoints are the same regardless of the values of any embedded [policies]. Embedded policies are not authoritative and may be stale or incoherent with the policies associated with the endpoint.
The [address] properties of two endpoint references are compared according to
Section 6 of [
they contain the same number of individual properties;
for each reference property in one endpoint reference there exists an equivalent reference property in the other. One [reference property] is equivalent to another [reference property] if their byte streams per Exclusive XML Canonicalization are equal.
Therefore, a consuming application should assume that different XML Schemas, WSDL definitions and policies apply to endpoint references whose address or reference properties differ.
This section defines the information model and syntax of message addressing properties.
Message addressing properties enable the identification and location of the endpoints involved in an interaction. The basic interaction pattern from which all others are composed is "one way". In this pattern a source sends a message to a destination without any further definition of the interaction. "Request Reply" is a common interaction pattern that consists of an initial message sent by a source endpoint (the request) and a subsequent message sent from the destination of the request back to the source (the reply). A reply can be either an application message, a fault, or any other message.
Message addressing properties collectively augment a message with the following abstract properties to support one way, request reply, and any other interaction pattern:
The address of the intended receiver of this message.
Reference of the endpoint where the message originated from.
An endpoint reference that identifies the intended receiver for replies
to this message. If a reply is expected, a message MUST contain a [reply
endpoint]. The sender MUST use the contents of the [reply endpoint] to
formulate the reply message as defined in
An endpoint reference that identifies the intended receiver for faults
related to this message. When formulating a fault message as defined in
An identifier that uniquely (and opaquely) identifies the semantics implied by this message.
It is RECOMMENDED that value of the [action] property is a URI
identifying an input, output, or fault message within a WSDL port type.
An action may be explicitly or implicitly associated with the
corresponding WSDL definition. Web Services Addressing - WSDL
Binding
A URI that uniquely identifies this message in time and space. No two messages with a distinct application intent may share a [message id] property. A message MAY be retransmitted for any purpose including communications failure and MAY use the same [message id] property. The value of this property is an opaque URI whose interpretation beyond equivalence is not defined in this specification. If a reply is expected, this property MUST be present.
A pair of values that indicate how this message relates to another
message. The type of the relationship is identified by a QName. The
related message is identified by a URI that corresponds to the related
message's [message id] property. The message identifier URI may refer to
a specific message, or be the following well-known URI that means
"unspecified message": http://www.w3.org/2004/12/addressing
This specification has one predefined relationship type as shown in
QName | Description |
---|---|
wsa:Reply | Indicates that this is a reply to the message identified by the URI. |
A reply message MUST contain a [relationship] property consisting of wsa:Reply and the message id property of the request message.
The dispatching of incoming messages is based on two message properties. The mandatory "destination" and "action" fields identify the target processing location and the verb or intent of the message.
Due to the range of network technologies currently in wide-spread use (e.g., NAT,
DHCP, firewalls), many deployments cannot assign a meaningful global URI to a given
endpoint. To allow these "anonymous" endpoints to initiate message exchange patterns
and receive replies, WS-Addressing defines the following well-known URI for use by
endpoints that cannot have a stable, resolvable URI: http://www.w3.org/2004/12/addressing
Requests whose [reply endpoint], [source endpoint] and/or [fault endpoint] use this address MUST provide some out-of-band mechanism for delivering replies or faults (e.g. returning the reply on the same transport connection). This mechanism may be a simple request/reply transport protocol (e.g., HTTP GET or POST). This URI MAY be used as the [destination] for reply messages and SHOULD NOT be used as the [destination] in other circumstances.
Message addressing properties provide end-to-end characteristics of a message that can be easily secured as a unit. These properties are immutable and not intended to be modified along a message path.
The following describes the XML Infoset representation of message addressing properties:
The following describes the attributes and elements listed in the schema overview above:
This OPTIONAL element (of type xs:anyURI) conveys the [message id] property. This element MUST be present if wsa:ReplyTo or wsa:FaultTo is present.
This OPTIONAL (repeating) element information item contributes one abstract [relationship] property value, in the form of a (URI, QName) pair. The [children] property of this element (which is of type xs:anyURI) conveys the [message id] of the related message. This element MUST be present if the message is a reply.
This OPTIONAL attribute (of type xs:QName) conveys the relationship type as a QName. When absent, the implied value of this attribute is wsa:Reply.
This OPTIONAL element (of type wsa:EndpointReferenceType) provides the value for the [reply endpoint] property. This element MUST be present if a reply is expected. If this element is present, wsa:MessageID MUST be present.
This OPTIONAL element (of type wsa:EndpointReferenceType) provides the value for the [source endpoint] property.
This OPTIONAL element (of type wsa:EndpointReferenceType) provides the value for the [fault endpoint] property. If this element is present, wsa:MessageID MUST be present.
This REQUIRED element (of type xs:anyURI) provides the value for the [destination] property.
This REQUIRED element of type xs:anyURI conveys the [action] property. The [children] of this element convey the value of this property.
The reply to a WS-Addressing compliant request message MUST be compliant to WS-Addressing and be constructed according to the rules defined in this section.
The following example illustrates a request message using message information header blocks in a SOAP 1.2 message:
This message would have the following property values:
[destination] The URI mailto:joe@fabrikam123.example
[reply endpoint] The endpoint with [address] http://business456.example/client1
[action] http://fabrikam123.example/mail/Delete
[message id] http://example.com/someuniquestring
The following example illustrates a reply message using message information header blocks in a SOAP 1.2 message:
This message would have the following property values:
[destination] http://business456.example/client1
[action] http://fabrikam123.example/mail/DeleteAck
[message id] http://example.com/someotheruniquestring
[relationship] (wsa:Reply, http://example.com/someuniquestring)
TBD
Placeholder for auto change log generation.