Web Services Transfer (WS-Transfer)
Latest version:
http://www.w3.org/TR/ws-transfer
Previous version:
http://www.w3.org/TR/2009/WD-ws-transfer-20090317
Editors:
Doug Davis, IBM
Ashok Malhotra,
Oracle
Katy Warr,
IBM
Wu Chou, Avaya
Copyright © 2009 W3C®
(MIT,
ERCIM,
Keio), All Rights Reserved. W3C liability,
trademark
and document
use rules apply.
This specification describes a general
SOAP-based protocol for accessing XML representations of Web service-based
resources.
This document is an editors' copy that
has no official standing.
1 Introduction
1.1 Requirements
2 Terminology and Notation
2.1 Terminology
2.2 XML Namespaces
2.3 Notational Conventions
2.4 Considerations on the Use of
Extensibility Points
2.5 Compliance
3 Resource Operations
3.1 Get
3.2 Put
3.3 Delete
4 Resource Factory Operations
4.1 Create
5 Faults
5.1 InvalidRepresentation
5.2 UnknownDialect
5.3 PutDenied
5.4 UnknownResource
6 Security Considerations
7 WS-Transfer Metadata
7.1 TransferResource
Assertion
7.2 TransferResourceFactory
Assertion
8 Acknowledgements
9 References
9.1 Normative References
9.2 Informative References
A XML Schema
B WSDL
C Change Log
This specification defines a mechanism for
acquiring XML-based representations of entities using the Web service
infrastructure. It defines two types of entities:
·
Resources, which are entities addressable by
an endpoint reference that provide an XML representation
·
Resource factories, which are Web services
that can create new resources
Specifically, it defines two operations for
sending and receiving the representation of a given resource and two operations
for creating and deleting a resource and its corresponding representation.
Note that the state maintenance of a resource
is at most subject to the "best efforts" of the hosting server. When
a client receives the server's acceptance of a request to create or update a
resource, it can reasonably expect that the resource now exists at the
confirmed location and with the confirmed representation, but this is not a
guarantee, even in the absence of any third parties. The server MAY change the
representation of a resource, MAY remove a resource entirely, or MAY bring back
a resource that was deleted.
For instance, the server might store resource
state information on a disk drive. If that drive crashes and the server
recovers state information from a backup tape, changes that occurred after the
backup was made will be lost.
A server MAY have
other operational processes that change resource state information. For
example, A server might run a background process that
examines resources for objectionable content and deletes any such resources it
finds. A a server can could
purge resources that have not been accessed for some period of
time. A server could apply storage quotas that cause it
to occasionally purge resources.
In addition to this,
there may be application or process specific
reasons for a server to augment or transform the representation
provided by an update or create
operation. For example, the server might
populate the optional properties of a newly created resource with meaningful
default values.
Finally all clients
need to be aware that there might be
other clients simultaneously accessing, creating,
and updating the same resources.
In essence, the confirmation by a service of
having processed a request to create, modify, or delete a resource implies a
commitment only at the instant that the confirmation was generated. While the
usual case is that resources are long-lived and stable, there are no
guarantees, and clients are advised to code defensively.
There is no requirement for uniformity in
resource representations between the messages defined in this specification.
For example, the representations required by Create or Put can differ from the
representation returned by Get, depending on the semantic requirements of the
service. Additionally, there is no requirement that the resource content is
fixed for any given endpoint reference. The resource content can vary based on
environmental factors, such as the security context, time of day,
configuration, or the dynamic state of the service.
This specification intends to meet the
following requirements:
·
Provide a SOAP-based protocol for managing
resources and their representations.
·
Minimize additional mechanism beyond the
current Web Services architecture.
Resource
A Web service that is addressable using an endpoint reference and can be
represented by an XML Information Set. The representation can be retrieved using
the Get operation and can be manipulated using the Put and Delete operations.
Resource factory
A Web
service that is capable of creating new resources using the Create operation
defined in this specification.
The XML Namespace URI that MUST be used by
implementations of this specification is:
Table 2-1 lists XML namespaces that are used in this
specification. The choice of any namespace prefix is arbitrary and not
semantically significant.
|
Table 2-1:
Prefixes and XML Namespaces used in this specification. |
||
|
Prefix |
XML
Namespace |
Specification(s)
|
|
wst
|
This
specification |
|
|
s |
Either SOAP
1.1 or 1.2 |
SOAP |
|
s11 |
||
|
s12 |
||
|
wsa |
||
|
wsdl |
||
|
xs |
XML Schema [XMLSchema - Part 1], [XMLSchema - Part 2] |
|
The
working group intends to update the value of the Web Services Transfer
namespace URI each time a new version of this document is published until such
time that the document reaches Candidate Recommendation status. Once it has
reached Candidate Recommendation status, the working group intends to maintain
the value of the Web Services Transfer namespace URI that was assigned in the
Candidate Recommendation unless significant changes are made that impact the
implementation or break post-CR implementations of the specification. Also see http://www.w3.org/2001/tag/doc/namespaceState.html
and http://www.w3.org/2005/07/13-nsuri
.
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 [RFC
2119].
This
specification uses the following syntax to define outlines for messages:
·
The syntax appears as an XML instance, but
values in italics indicate data types instead of literal values.
·
Characters are appended to elements and
attributes to indicate cardinality:
o
"?" (0 or 1)
o
"*" (0 or more)
o
"+" (1 or more)
·
The character "|" is used to
indicate a choice between alternatives.
·
The characters "(" and
")" are used to indicate that contained items are to be treated as a
group with respect to cardinality or choice.
·
The characters "[" and
"]" are used to call out references and property names.
·
Ellipsis (i.e.
"...") indicate points of extensibility.
·
XML namespace prefixes (see Table 2-1) are used to indicate the namespace of the
element being defined.
In
addition to Message Information Header properties [WS-Addressing],
this specification uses the following properties to define messages:
[Headers]
Unordered message headers.
[Action]
The value to be used for the wsa:Action IRI.
[Body]
A message body.
These
properties bind to a SOAP Envelope as follows:
<s:Envelope>
<s:Header>
[Headers]
<wsa:Action>[Action]</wsa:Action>
...
</s:Header>
<s:Body>[Body]</s:Body>
</s:Envelope>
This
specification can be used in terms of XML Information Set (Infoset)
[XML Infoset], even though
the specification uses XML 1.0 terminology. Valid Infoset
for this specification is the one serializable in XML
1.0, hence the use of XML 1.0.
The
term "generate" is used in relation to the various faults defined by
this specification to imply that a fault is produced and no futher
processing SHOULD be performed. In these cases the fault SHOULD be transmitted.
However, there might be reasons when a compliant implementation can choose not
to transmit the fault - for example, security concerns - in these situations
the fault MAY NOT be transmitted.
The elements defined in this specification
MAY be extended at the points indicated by their outlines and schema.
Implementations MAY add child elements and/or attributes at the indicated
extension points but MUST NOT contradict the semantics of the parent and/or
owner, respectively. If a receiver does not recognize an extension, the
receiver SHOULD ignore that extension. Senders MAY indicate the presence of an
extension that has to be understood through the use of a corresponding SOAP Header
with a soap:mustUnderstand
attribute with the value "1".
In cases where it is either desirable or
necessary for the receiver of a request that has been extended to indicate that
it has recognized and accepted the semantics associated with that extension, it
is RECOMMENDED that the receiver add a corresponding extension to the response
message. The definition of an extension SHOULD clearly specify how the
extension that appears in the response correlates with that in the
corresponding request.
Extension elements and attributes MUST NOT
use the Web Services Transfer namespace URI.
An implementation is not compliant with this
specification if it fails to satisfy one or more of the MUST or REQUIRED level
requirements defined herein. A SOAP Node MUST NOT use the XML namespace
identifier for this specification (listed in 2.2
XML Namespaces) within SOAP Envelopes unless it is compliant with this
specification.
Normative
text within this specification takes precedence over the XML Schema and WSDL
descriptions, which in turn take precedence over outlines, which in turn take
precedence over examples.
All
messages defined by this specification MUST be sent to a Web service that is
addressable by an EPR (see [WS-Addressing]).
Unless
otherwise noted, all IRIs are absolute IRIs and IRI comparison MUST be performed according to [RFC 3987] section 5.3.1.
For
any message defined by this specification, any OPTIONAL elements or attributes
in the message MAY be used by senders of the message,
however receivers of those messages MUST support those OPTIONAL elements and
attributes, unless other behavior is explicitly defined by this specification.
This specification defines one Web service
operation (Get) for fetching a one-time snapshot of the representation of a
resource. This operation MUST be supported by compliant WS-Transfer resources.
The Get request message MUST be of the following
form:
[Action]
http://www.w3.org/2009/09/ws-tra/Get
[Body]
<wst:Get Dialect="xs:anyURI"? ...>
xs:any*
</wst:Get>
The following describes additional, normative
constraints on the outline listed above:
[Body]/wst:Get
This is a REQUIRED
element that has no defined child element content.
[Body]/wst:Get@Dialect
When this OPTIONAL
attribute is present it contains a IRI that refers to
additional information for the service on how to process this element. If the
attribute is present but the dialect IRI is not known then the service MUST
generate an wst:UnknownDialect
fault. There is no default value for the attribute. If the attribute is absent,
then the base behavior is used.
[Body]/wst:Get@Dialect="http://www.w3.org/2009/09/ws-fra"
The WS-Fragment [WS-Fragment] specification defines this dialect IRI. Use of
this IRI indicates that the contents of the Get element MUST be processed as
specified by the WS-Fragment [WS-Fragment] specification.
If
the request message reaches a conformant implementation of WS-Transfer and the
message refers to an unknown resource, then the implementation MUST generate a wst:UnknownResource fault.
A
Get request MUST be targeted at the resource whose representation is desired as
described in 2 Terminology and Notation
of this specification.
If
the resource accepts a Get request, it MUST reply with a response of the
following form:
[Action]
http://www.w3.org/2009/09/ws-tra/GetResponse
[Body]
<wst:GetResponse
...>
<wst:Representation>
xs:any?
</wst:Representation>
xs:any*
</wst:GetResponse>
The
following describes additional, normative constraints on the outline listed
above:
[Body]/wst:GetResponse/wst:Representation
This REQUIRED element acts as a container
for the representation of the resource.MUST have
as its first child element, an
element that comprises the
representation of the resource. This
element MAY have no children in cases where there
is no resource representation.
Other
components of the outline above are not further constrained by this
specification.
This
operation is safe; it will not result in any side effect imputable to the
requester. This means that in case of an underlying protocol error that might
get unnoticed, resending the same request can be done automatically.
The
following shows a sample SOAP envelope containing a Get request:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:ReplyTo>
<wsa:Address>
http://www.fabrikam123.example.org/pullport
</wsa:Address>
</wsa:ReplyTo>
<wsa:To>http://www.example.org/repository</wsa:To>
<xxx:CustomerID wsa:IsReferenceParameter="true">
732199
</xxx:CustomerID>
<xxx:Region wsa:IsReferenceParameter="true">
EMEA
</xxx:Region>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/Get
</wsa:Action>
<wsa:MessageID>
uuid:00000000-0000-0000-C000-000000000046
</wsa:MessageID>
</s:Header>
<s:Body>
<wst:Get/>
</s:Body>
</s:Envelope>
The
following shows the corresponding response message:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:To>http://www.fabrikam123.example.org/pullport</wsa:Address>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/GetResponse
</wsa:Action>
<wsa:MessageID>
uuid:0000010e-0000-0000-C000-000000000046
</wsa:MessageID>
<wsa:RelatesTo>
uuid:00000000-0000-0000-C000-000000000046
</wsa:RelatesTo>
</s:Header>
<s:Body>
<wst:GetResponse>
<wst:Representation>
<xxx:Customer>
<xxx:first>
<xxx:address>
<xxx:city>
<xxx:state>CA</xxx:state>
<xxx:zip>90266</xxx:zip>
</xxx:Customer>
</wst:Representation>
</wst:GetResponse>
</s:Body>
</s:Envelope>
In
this example, the representation of the resource is the following XML element:
<xxx:Customer>
<xxx:first>
<xxx:address>
<xxx:city>
<xxx:state>CA</xxx:state>
<xxx:zip>90266</xxx:zip>
</xxx:Customer>
This specification defines one Web service
operation (Put) for updating a resource by providing a replacement
representation. This operation MAY be supported by compliant WS-Transfer
resources. A resource MAY accept updates that provide different XML representations
than that returned by the resource; in such a case, the semantics of the update
operation is defined by the resource.
Unless otherwise specified by an extension,
this operation will replace the entire XML representation of the resource, and any
OPTIONAL values (elements or attributes) not specified in the Put request
message will be set to a resource-specific default value.
The Put request message MUST be of the
following form:
[Action]
http://www.w3.org/2009/09/ws-tra/Put
[Body]
<wst:Put Dialect="xs:anyURI"? ...>
<wst:Representation>
xs:any?
</wst:Representation>
xs:any*
</wst:Put>
The following describes additional, normative
constraints on the outline listed above:
[Body]/wst:Put
This REQUIRED element MUST have as its first child
element, an element that comprises the representation of the resource that is
to be replaced.
[Body]/wst:Put@Dialect
When this OPTIONAL
attribute is present it contains a IRI that refers to
additional information for the service on how to process this element. If the
attribute is present but the dialect IRI is not known then the service MUST
generate an wst:UnknownDialect
fault. There is no default value for the attribute. If the attribute is absent,
then the base behavior is used.
[Body]/wst:Put@Dialect="http://www.w3.org/2009/09/ws-fra"
The WS-Fragment [WS-Fragment] specification defines this dialect IRI. Use of
this IRI indicates that the contents of the Put element MUST be processed as
specified by the WS-Fragment [WS-Fragment] specification.
[Body]/wst:Put/wst:Representation
This REQUIRED element acts
as a container for the representation of the resource. This
element MAY have no children. This case
MUST be interpreted as a request to remove the resource’s
representation, not the resource itself.
If
the request message reaches a conformant implementation of WS-Transfer and the
message refers to an unknown resource, then the implementation MUST generate a wst:UnknownResource fault.
A
Put request MUST be targeted at the resource whose representation is desired to
be replaced, as described in 2
Terminology and Notation of this specification.
If
an implementation that performs schema validation on a presented representation
detects that the presented representation is invalid for the target resource,
then the implementation MUST generate a wst:InvalidRepresentation fault. The replacement
representation could be considered to be invalid if it does not conform to the
schema(s) for the target resource or otherwise violates some cardinality or
type constraint.
The
replacement representation could contain within it element or attribute values
that are different than their corresponding values in the current representation.
Such changes could affect elements or attributes that, for whatever reason, the
implementation does not wish to allow the client to change. An implementation
MAY choose to ignore such elements or attributes. If an implementation does not
ignore those elements or attributes, it MUST generate a wst:PutDenied fault. See 5 Faults.
Other
components of the outline above are not further constrained by this
specification.
A
successful Put operation updates the current representation associated with the
targeted resource. An unsuccessful Put operation does not affect the resource.
If
the resource accepts a Put request and performs the requested update, it MUST
reply with a response of the following form:
[Action]
http://www.w3.org/2009/09/ws-tra/PutResponse
[Body]
<wst:PutResponse
...>
<wst:Representation>
xs:any?
</wst:Representation>?
xs:any*
</wst:PutResponse>
[Body]/wst:PutResponse/wst:Representation
This OPTIONAL element acts as a container for the
representation of the resource.This
REQUIRED element, if it contains any child elements, MUST have as its first
child element, an element that comprises the representation of the resource
that has been updated.
This element is intended for use as an optimization
to save the client the overhead of having to
perform a subsequent Get operation. As
an optimization and as a service to the requester, if there are no extension
elements this element SHOULD be empty if the updated representation does not
differ from the representation sent in the Put request message; that is, if the
service accepted the new representation verbatim.
Such a response (an empty wst:PutResponse) implies
that the update request was successful in its entirety (assuming no intervening
mutating operations are performed). A service MAY include
this element to return the current representation of the resource as
the child of the wst:PutResponse element even in this case, however.
This element MAY
have no children in cases where there is no resource representation.
Other
components of the outline above are not further constrained by this
specification.
The
following shows a sample SOAP envelope containing a Put request:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:ReplyTo>
<wsa:Address>
http://www.fabrikam123.example.org/sender
</wsa:Address>
</wsa:ReplyTo>
<wsa:To>http://www.example.org/pushport</wsa:To>
<xxx:CustomerID wsa:IsReferenceParameter="true">
732199
</xxx:CustomerID>
<xxx:Region wsa:IsReferenceParameter="true">
EMEA
</xxx:Region>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/Put
</wsa:Action>
<wsa:MessageID>
uuid:00000000-0000-0000-C000-000000000047
</wsa:MessageID>
</s:Header>
<s:Body>
<wst:Put>
<xxx:Customer>
<xxx:first>
<xxx:address>
<xxx:city>
<xxx:state>CA</xxx:state>
<xxx:zip>90266</xxx:zip>
</xxx:Customer>
</wst:Put>
</s:Body>
</s:Envelope>
The
following shows the corresponding response message indicating success:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:To>http://www.fabrikam123.example.org/sender</wsa:Address>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/PutResponse
</wsa:Action>
<wsa:MessageID>
uuid:0000010e-0000-0000-C000-000000000047
</wsa:MessageID>
<wsa:RelatesTo>
uuid:00000000-0000-0000-C000-000000000047
</wsa:RelatesTo>
</s:Header>
<s:Body>
<wst:PutResponse/>
</s:Body>
</s:Envelope>
This specification defines one Web service
operation (Delete) for deleting a resource in its entirety. This operation MAY
be supported by compliant WS-Transfer resources.
The Delete request message MUST be of the
following form:
[Action]
http://www.w3.org/2009/09/ws-tra/Delete
[Body]
<wst:Delete Dialect="xs:anyURI"? ...>
xs:any*
</wst:Delete>
The following describes additional, normative
constraints on the outline listed above:
[Body]/wst:Delete
This is a REQUIRED
element that has no defined child element content. However, it MAY include
child element content as defined by an extension(s).
[Body]/wst:Delete@Dialect
When this OPTIONAL
attribute is present it contains a IRI that refers to
additional information for the service on how to process this element. If the
attribute is present but the dialect IRI is not known then the service MUST
generate an wst:UnknownDialect
fault. There is no default value for the attribute. If the attribute is absent,
then the base behavior is used.
[Body]/wst:Delete@Dialect="http://www.w3.org/2009/09/ws-fra"
The WS-Fragment [WS-Fragment] specification defines this dialect IRI. Use of
this IRI indicates that the contents of the Delete element MUST be processed as
specified by the WS-Fragment [WS-Fragment] specification.
If
the request message reaches a conformant implementation of WS-Transfer and the
message refers to an unknown resource, then the implementation MUST generate a wst:UnknownResource fault.
A
Delete request MUST be targeted at the resource to be deleted as described in 2 Terminology and Notation of this
specification.
Other
components of the outline above are not further constrained by this
specification.
A
successful Delete operation deletes the targeted resource.
If
the resource accepts a Delete request, it MUST reply with a response of the
following form:
[Action]
http://www.w3.org/2009/09/ws-tra/DeleteResponse
[Body]
<wst:DeleteResponse
...>
xs:any*
</wst:DeleteResponse>
[Body]/wst:DeleteResponse
This REQUIRED element has no defined child element
content.
Other
components of the outline above are not further constrained by this
specification.
The
following shows a sample SOAP envelope containing a Delete request:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:ReplyTo>
<wsa:Address>
http://www.fabrikam123.example.org/sender
</wsa:Address>
</wsa:ReplyTo>
<wsa:To>http://www.example.org/pushport</wsa:To>
<xxx:CustomerID wsa:IsReferenceParameter="true">
732199
</xxx:CustomerID>
<xxx:Region wsa:IsReferenceParameter="true">
EMEA
</xxx:Region>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/Delete
</wsa:Action>
<wsa:MessageID>
uuid:00000000-0000-0000-C000-000000000049
</wsa:MessageID>
</s:Header>
<s:Body>
<wst:Delete/>
</s:Body>
</s:Envelope>
The
following shows the corresponding response message indicating success:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:To>http://www.fabrikam123.example.org/sender</wsa:Address>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/DeleteResponse
</wsa:Action>
<wsa:MessageID>
uuid:0000010e-0000-0000-C000-000000000049
</wsa:MessageID>
<wsa:RelatesTo>
uuid:00000000-0000-0000-C000-000000000049
</wsa:RelatesTo>
</s:Header>
<s:Body>
<wst:DeleteResponse/>
</s:Body>
</s:Envelope>
This specification defines one Web
service operation (Create) for creating a resource and providing its initial
representation. This operation MAY be supported by compliant WS-Transfer
resource factories. In some cases, the initial representation MAY constitute
the representation of a logical constructor for the resource and can thus
differ structurally from the representation returned by Get or the one required
by Put. This is because the parameterization requirement for creating a
resource is often distinct from the steady-state representation of the
resource. Implementations SHOULD provide metadata which describes the use of
the representation and how it relates to the resource which is created, but
such mechanisms are beyond the scope of this specification. The resource
factory that receives a Create request will allocate a new resource that is
initialized from the presented representation. The new resource will be
assigned a service-determined endpoint reference that is returned in the
response message.
The Create request message MUST be of
the following form:
[Action]
http://www.w3.org/2009/09/ws-tra/Create
[Body]
<wst:Create Dialect="xs:anyURI"? ...>
<wst:Representation>
xs:any?
</wse:Representation>?
xs:any*
</wst:Create>
The following describes additional,
normative constraints on the outline listed above:
[Body]/wst:Create
This
REQUIRED element MAY contain zero or more child elements. If this element does
not contain a child element then the resource will be created using default
values. The first child element, if present, MUST be the literal resource
representation, a representation of the constructor for the resource, or other
instructions for creating the resource. If present, any extension elements MUST
be included after the mandated first child element.
[Body]/wst:Create@Dialect
When this
OPTIONAL attribute is present it contains a IRI that
refers to additional information for the service on how to process this
element. If the attribute is present but the dialect IRI is not known then the
service MUST generate an wst:UnknownDialect
fault. There is no default value for the attribute. If the attribute is absent,
then the base behavior is used.
[Body]/wst:Create@Dialect="http://www.w3.org/2009/09/ws-fra"
The
WS-Fragment [WS-Fragment] specification defines
this dialect IRI. Use of this IRI indicates that the contents of the Create
element MUST be processed as specified by the WS-Fragment [WS-Fragment]
specification.
[Body]/wst:Create/wst:Representation
This OPTIONAL element
acts as a container for the representation of the resource.
If this element is
not present the resource MUST be
created using default values (equivalent to a null
constructor). This element MAY have
no children, in which case the resource
MUST be created with an
empty representation (equivalent to an
empty constructor).
A
Create request MUST be targeted at a resource factory capable of creating the
desired new resource. This factory is distinct from the resource being created
(which by definition does not exist prior to the successful processing of the
Create request message).
If
an implementation that performs schema validation on a presented representation
detects that the presented representation is invalid for the target resource,
then the implementation MUST generate a wst:InvalidRepresentation fault.
Other
components of the outline above are not further constrained by this
specification.
If
the resource factory accepts a Create request, it MUST reply with a response of
the following form:
[Action]
http://www.w3.org/2009/09/ws-tra/CreateResponse
[Body]
<wst:CreateResponse
...>
<wst:ResourceCreated>endpoint-reference</wst:ResourceCreated>
<wst:Representation>
xs:any?
</wst:Representation>?
xs:any*
</wst:CreateResponse>
[Body]/wst:CreateResponse
This REQUIRED element MUST have as its first child
element an Endpoint Reference (wst:ResourceCreated element) to the newly
created resource.
A service MUST also return the current
representation of the new resource as the second child of the
wst:CreateResponse element if the created representation logically differs from
the representation sent in the Create request message. That is, the initial
representation is returned if one or more values present in Create message was
specifically overridden with a different value during resource creation. If
default values are used to complete a resource creation which were not present
in the Create message, then this does not constitute a logical difference.
As an optimization and as a service to the
requestor, the wst:CreateResponse element of the response message SHOULD be
empty, other than the ResourceCreated element, if the created representation
does not logically differ from the representation sent in the Create request
message and there are no extension elements; that is, if the service accepted
the new representation or creation instructions verbatim. Such a response
indicates that the request was completely successful (assuming no intervening
mutating operations are performed). A service MAY return the current
representation of the resource as the second child of the wst:CreateResponse
element even in this case, however.
[Body]/wst:CreateResponse/wst:ResourceCreated
This required element MUST be an endpoint reference for
the newly created resource. This endpoint reference MUST identify the resource
for future Get, Put, and Delete operations.
[Body]/wst:CreateResponse
This OPTIONAL element
acts as a container for the representation of the resource.
This element is
intended for use as an optimization to save the client the overhead of having
to perform a subsequent Get operation. A service MAY include this element to return
the current representation of the resource.
This element MAY have
no children in cases where there is no resource representation.
Other
components of the outline above are not further constrained by this
specification.
The
following shows a sample SOAP envelope containing a Create request:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:ReplyTo>
<wsa:Address>
http://www.fabrikam123.example.org/sender
</wsa:Address>
</wsa:ReplyTo>
<wsa:To>http://www.example.org/pushport/CustomerSpace</wsa:To>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/Create
</wsa:Action>
<wsa:MessageID>
uuid:00000000-0000-0000-C000-000000000048
</wsa:MessageID>
</s:Header>
<s:Body>
<wst:Create>
<wst:Representation>
<xxx:Customer>
<xxx:first>
<xxx:address>
<xxx:city>
<xxx:state>CA</xxx:state>
<xxx:zip>90266</xxx:zip>
</xxx:Customer>
</wst:Representation>
</wst:Create>
</s:Body>
</s:Envelope>
The
following shows the corresponding response message indicating success:
<s:Envelope
xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:wsa="http://www.w3.org/2005/08/addressing"
xmlns:wst="http://www.w3.org/2009/09/ws-tra"
xmlns:xxx="http://fabrikam123.example.com/resource-model"
>
<s:Header>
<wsa:To>http://www.fabrikam123.example.org/sender</wsa:Address>
<wsa:Action>
http://www.w3.org/2009/09/ws-tra/CreateResponse
</wsa:Action>
<wsa:MessageID>
uuid:0000010e-0000-0000-C000-000000000048
</wsa:MessageID>
<wsa:RelatesTo>
uuid:00000000-0000-0000-C000-000000000048
</wsa:RelatesTo>
</s:Header>
<s:Body>
<wst:CreateResponse>
<wst:ResourceCreated>
<wsa:Address>http://www.example.org/pushport</wsa:Address>
<wsa:ReferenceParameters>
<xxx:CustomerID>732199</xxx:CustomerID>
<xxx:Region>EMEA</xxx:Region>
</wsa:ReferenceParameters>
</wst:ResourceCreated>
</wst:CreateResponse>
</s:Body>
</s:Envelope>
All fault messages defined in this
specification MUST be sent according to the rules and usage described in [WS-Addressing 1.0 SOAP Binding] Section 6 for encoding
SOAP 1.1 and SOAP 1.2 faults. The [Action] property below MUST be used
for faults defined in this specification:
The
definitions of faults in this section use the following properties:
[Code] The fault code.
[Subcode] The fault subcode.
[Reason] The English language reason element.
[Detail] The detail element. If
absent, no detail element is defined for the fault.
For
SOAP 1.2, the [Code] property MUST be either "Sender" or
"Receiver". These properties are serialized into text XML as follows:
|
Sender
|
Receiver
|
|
|
SOAP 1.2 |
s12:Sender |
s12:Receiver |
The properties above bind to a SOAP 1.2 fault
as follows:
<s12:Envelope>
<s12:Header>
<wsa:Action> [Action]
</wsa:Action>
<!--
Headers elided for brevity. -->
</s12:Header>
<s12:Body>
<s12:Fault>
<s12:Code>
<s12:Value>[Code]</s12:Value>
<s12:Subcode>
<s12:Value>[Subcode]</s12:Value>
</s12:Subcode>
</s12:Code>
<s12:Reason>
<s12:Text xml:lang="en">[Reason]</s12:Text>
</s12:Reason>
<s12:Detail>
[Detail]
...
</s12:Detail>
</s12:Fault>
</s12:Body>
</s12:Envelope>
The properties bind to a SOAP 1.1 fault as
follows:
<s11:Envelope>
<s11:Body>
<s11:Fault>
<faultcode>[Subcode]</faultcode>
<faultstring xml:lang="en">[Reason]</faultstring>
<detail>
[Detail]
...
</detail>
</s11:Fault>
</s11:Body>
</s11:Envelope>
This fault MUST be
generated when an incorrect representation is sent in a wst:Put or wst:Create message.
|
[Code] |
s:Sender |
|
[Subcode] |
wst:InvalidRepresentation |
|
[Reason] |
The supplied representation is invalid |
|
[Detail] |
none |
This fault MUST be generated when a
service detects an unknown Dialect IRI in a request message.
|
[Code] |
s:Sender |
|
[Subcode] |
wst:UnknownDialect |
|
[Reason] |
The specified Dialect IRI is not known.
|
|
[Detail] |
The unknown IRI if specified |
This fault MUST be generated when a Put
request message attempts to modify a portion of a resource but is not allowed
to do so.
|
[Code] |
s:Sender |
|
[Subcode] |
wst:UpdateDenied |
|
[Reason] |
One or more elements or attributes
cannot be updated. |
|
[Detail] |
An OPTIONAL list of the QNames of the elements or attributes that are not allowed
to be updated. |
This fault MUST be generated when a
request specifies a resource that is not known.
|
[Code] |
s:Sender |
|
[Subcode] |
wst:UnknownResource |
|
[Reason] |
The resource is not known. |
|
[Detail] |
none |
It is strongly
RECOMMENDED that the communication between services be secured using the
mechanisms described in [WS-Security].
In
order to properly secure messages, the body (even if empty) and all relevant
headers need to be included in the signature. Specifically, the WS-Addressing
header blocks, WS-Security timestamp, and any header blocks resulting from a <wsa:ReferenceParameters> in
references need to be signed along with the body in order to "bind"
them together and prevent certain types of attacks.
If
a requestor is issuing multiple messages to a resource reference, then it is
RECOMMENDED that a security context be established using the mechanisms
described in WS-Trust and WS-SecureConversation. It
is further RECOMMENDED that if shared secrets are used, message-specific
derived keys also be used to protect the secret from crypto attacks.
The
access control semantics of resource references is out-of-scope of this
specification and are specific to each resource reference. Similarly, any
protection mechanisms on resource references independent of transfer (e.g.
embedded signatures and encryption) are also out-of-scope.
It
is RECOMMENDED that the security considerations of WS-Security also be
considered.
While
a comprehensive listing of attacks is not feasible, the following list
summarizes common classes of attacks that apply to this protocol and identifies
the mechanism(s) to prevent/mitigate the attacks.
·
Replay - Messages, or
portions of messages, can be replayed in an attempt to gain access or disrupt
services. Freshness checks such as timestamps, digests, and sequences can be
used to detect duplicate messages.
·
Invalid tokens - There are a
number of token attacks including certificate authorities, false signatures,
and PKI attacks. Care SHOULD be taken to ensure each token is valid (usage
window, digest, signing authority, revocation, ...),
and that the appropriate delegation policies are in compliance.
·
Man-in-the-middle - The message
exchanges in this specification could be subject to man-in-the-middle attacks
so care SHOULD be taken to reduce possibilities here such as establishing a
secure channel and verifying that the security tokens user represent identities
authorized to speak for, or on behalf of, the desired resource reference.
·
Message alteration - Alteration is
prevented by including signatures of the message information using WS-Security.
Care SHOULD be taken to review message part references to ensure they haven't
been forged (e.g. ID duplication).
·
Message disclosure - Confidentiality
is preserved by encrypting sensitive data using WS-Security.
·
Key integrity - Key integrity is
maintained by using the strongest algorithms possible (by comparing secured
policies - see [WS-Policy] and [WS-SecurityPolicy] and
by using derived keys ([WS-SecureConversation]).
·
Authentication - Authentication is
established using the mechanisms described in WS-Security and WS-Trust. Each
message is authenticated using the mechanisms described in WS-Security.
·
Accountability - Accountability is
a function of the type of and string of the key and algorithms being used. In
many cases, a strong symmetric key provides sufficient accountability. However,
in some environments, strong PKI signatures are required.
·
Availability - All reliable
messaging services are subject to a variety of availability attacks. Replay
detection is a common attack and it is RECOMMENDED that this be addressed by
the mechanisms described in WS-Security. Other attacks, such as network-level
denial of service attacks are harder to avoid and are outside the scope of this
specification. That said, care SHOULD be taken to
ensure that minimal state is saved prior to any authenticating sequences.
An endpoint MAY indicate that it supports
WS-Transfer, or its features, by including the WS-Transfer Policy assertion
within its WSDL. By doing so the endpoint is indicating that the corresponding
WS-Transfer operations are supported by that endpoint even though they do not
explicitly appear in its WSDL.
The WS-Transfer WSDL containing the
operations indicated by the TransferResource
Assertion MAY be exposed as described in WS-MetadataExchange
[WS-MetadataExchange] Section
9. This WS-Transfer WSDL can be annotated to indicate any endpoint specific
metadata that might be needed by clients interacting with this service. For
example, the WSDL MAY have policy assertions that indicate a particular
security mechanism used to protect the WS-Transfer operations supported by this
endpoint.
The mechanism for indicating that a
binding or endpoint conforms to the WS-Transfer specification's definition of a
Transfer Resource is through the use of the Web Services Policy - Framework [WS-Policy] and Web Services Policy - Attachment [WS-Policy Attachment] specifications.
This
specification defines a policy assertion (wst:TransferResource). The wst:TransferResource policy assertion applies to the
endpoint policy subject.
For
WSDL 1.1, these assertions MAY be attached to wsdl11:port
or wsdl11:binding. For WSDL 2.0, they MAY be attached to wsdl20:endpoint or wsdl20:binding. A policy expression containing
the wst:TransferResource
policy assertion MUST NOT be attached to a wsdl:portType
or wsdl20:interface.
The
wst:TransferResource policy
assertion is a nested policy container assertion. The meaning of this
assertion, when present in a policy alternative, is that WS-Transfer is
required to communicate with the subject and that the subject is a WS-Transfer
Resource.
In
order to indicate that the subject supports WS-Transfer but does not require
its use, an additional policy alternative SHOULD be provided which does not
contain this assertion. The compact authoring style for an OPTIONAL policy
assertion (the wsp:Optional
attribute) provided by WS-Policy MAY be used to indicate two policy
alternatives, one which contains the policy assertion, and another which does
not.
The
normative outline of this assertion is:
<wst:TransferResource
...>
<wst:PutOperationSupported
.../> ?
<wst:DeleteOperationSupported
.../> ?
<wst:FaultOnPutDenied.../>
?
<wst:Dialect
...> xs:anyURI
</wst:Dialect> *
<wst:Resource ...> xs:QName
</wst:Resource> ?
...
</wst:TransferResource>
The
following describes additional, normative constraints on the outline listed
above:
/wst:TransferResource
This policy assertion specifies that WS-Transfer protocol
MUST be used when communicating with this endpoint and that the subject is a
Transfer Resource. This assertion has Endpoint Policy Subject. Unless support
for OPTIONAL operations is explicitly indicated by either the PutOperationSupported or DeleteOperationSupported
parameters only the Get operation is supported.
/wst:TransferResource/wst:PutOperationSupported
When present, this OPTIONAL parameter indicates that the
Put operation is supported by this endpoint.
/wst:TransferResource/wst:DeleteOperationSupported
When present, this OPTIONAL parameter indicates that the
Delete operation is supported by this endpoint.
/wst:TransferResource/wst:FaultOnPutDenied
When present, this OPTIONAL parameter indicates that
attempts to change portions of the representation that are read-only will
generate a wst:PutDenied
fault. If this parameter is not present, attempts to modify read-only portions
of the resource representation will be ignored without any fault being
generated.
/wst:TransferResource/wst:Dialect
When present, this OPTIONAL parameter indicates support
for the specified Dialect IRI.
/wst:TransferResource/wst:Resource
When present, this OPTIONAL parameter provides the QName referencing the Global Element Declaration (GED) or
type of this resource. This QName can be used in
order to retrieve the schema of the resource.
The mechanism for indicating that a
binding or endpoint conforms to the WS-Transfer specification's definition of a
Transfer Resource Factory is through the use of the Web Services Policy -
Framework [WS-Policy] and Web Services
Policy - Attachment [WS-Policy Attachment]
specifications.
This
specification defines a policy assertion (wst:TransferResourceFactory). The wst:TransferResourceFactory policy assertion applies to
the endpoint policy subject.
For
WSDL 1.1, these assertions MAY be attached to wsdl11:port
or wsdl11:binding. For WSDL 2.0, they MAY be attached to wsdl20:endpoint or wsdl20:binding. A policy expression containing
the wst:TransferResourceFactory
policy assertion MUST NOT be attached to a wsdl:portType
or wsdl20:interface.
The
wst:TransferResourceFactory
policy assertion is a nested policy container assertion. The meaning of this
assertion, when present in a policy alternative, is that WS-Transfer is
required to communicate with the subject and that the subject is a WS-Transfer
Resource Factory.
In
order to indicate that the subject supports WS-Transfer but does not require its
use, an additional policy alternative SHOULD be provided which does not contain
this assertion. The compact authoring style for an OPTIONAL policy assertion
(the wsp:Optional attribute)
provided by WS-Policy MAY be used to indicate two policy alternatives, one
which contains the policy assertion, and another which does not.
The
normative outline of this assertion is:
<wst:TransferResourceFactory
...>
<wst:Dialect
...> xs:anyURI
</wst:Dialect> *
...
</wst:TransferResourceFactory>
The
following describes additional, normative constraints on the outline listed
above:
/wst:TransferResourceFactory
This policy assertion specifies that WS-Transfer Create
operation MUST be used when communicating with this endpoint. This assertion
has Endpoint Policy Subject.
/wst:TransferResourceFactory/wst:Dialect
When present, this OPTIONAL parameter indicates support
for the specified Dialect IRI.
This specification has been developed as a
result of joint work with many individuals and teams, including: Ashok Malhotra (Oracle Corp.), Asir Vedamuthu (Microsoft Corp.), Bob Freund (Hitachi, Ltd.),
Doug Davis (IBM), Fred Maciel (Hitachi, Ltd.), Geoff Bullen (Microsoft Corp.), Gilbert Pilz
(Oracle Corp.), Greg Carpenter (Microsoft Corp.), Jeff Mischkinsky
(Oracle Corp.), Katy Warr (IBM), Li Li (Avaya Communications), Mark Little (Red Hat), Prasad Yendluri (Software AG), Ram Jeyaraman
(Microsoft Corp.), Sreedhara Narayanaswamy
(CA), Sumeet Vij (Software
AG), Vikas Varma (Software
AG), Wu Chou (Avaya Communications), Yves Lafon
(W3C).
Key words for use in RFCs to Indicate Requirement
Levels ,
.
A non-normative copy of the XML
schema is listed below for convenience.
targetNamespace='http://www.w3.org/2009/09/ws-tra'
xmlns:tns='http://www.w3.org/2009/09/ws-tra'
xmlns:xs='http://www.w3.org/2001/XMLSchema'
xmlns:wsa='http://www.w3.org/2005/08/addressing'
elementFormDefault='qualified'
namespace='http://www.w3.org/2005/08/addressing'
schemaLocation='http://www.w3.org/2006/03/addressing/ws-addr.xsd'
/>
<xs:any minOccurs='0'
maxOccurs='unbounded' namespace='##other' processContents='lax' />
<xs:attribute name='Dialect' type='xs:anyURI' use='optional' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:element name='GetResponse'>
<xs:any minOccurs='1'
maxOccurs='unbounded' namespace='##other' processContents='lax' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:any minOccurs='1'
maxOccurs='unbounded' namespace='##other' processContents='lax' />
<xs:attribute name='Dialect' type='xs:anyURI' use='optional' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:element name='PutResponse'>
<xs:any minOccurs='1'
namespace='##other' processContents='lax' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:any minOccurs='0'
maxOccurs='unbounded' namespace='##other' processContents='lax' />
<xs:attribute name='Dialect' type='xs:anyURI' use='optional' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:element name='DeleteResponse'>
<xs:any minOccurs='0'
namespace='##other' processContents='lax' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:any minOccurs='0'
maxOccurs='unbounded' namespace='##other' processContents='lax' />
<xs:attribute name='Dialect' type='xs:anyURI' use='optional' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:element name='CreateResponse'>
<xs:element name='ResourceCreated' type='wsa:EndpointReferenceType'
/>
<xs:any minOccurs='0'
namespace='##other' processContents='lax' />
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:extension base='xs:anyURI'>
<xs:anyAttribute
namespace='##other' processContents='lax'/>
<xs:anyAttribute namespace='##other' processContents='lax'/>
<xs:element name='TransferResource'>
<xs:element name='PutOperationSupported' type='tns:Empty'
<xs:element name='DeleteOperationSupported' type='tns:Empty'
<xs:element name='FaultOnPutDenied' type='tns:Empty'
minOccurs='0'/>
<xs:element name='Dialect' type='tns:URI' minOccurs='0'
<xs:element name='Resource' type='xs:QName' minOccurs='0'/>
<xs:any namespace='##other' processContents='lax'
minOccurs='0'
<xs:anyAttribute
namespace='##other' processContents='lax' />
<xs:element name='TransferResourceFactory'>
<xs:element name='Dialect' type='tns:URI' minOccurs='0'
<xs:any namespace='##other' processContents='lax' minOccurs='0'
<xs:anyAttribute
namespace='##other' processContents='lax' />
A non-normative copy of the WSDL
description is listed below for convenience.
targetNamespace='http://www.w3.org/2009/09/ws-tra'
xmlns:tns='http://www.w3.org/2009/09/ws-tra'
xmlns:wsa='http://www.w3.org/2005/08/addressing'
xmlns:wsam='http://www.w3.org/2007/05/addressing/metadata'
xmlns:wsdl='http://schemas.xmlsoap.org/wsdl/'
xmlns:xs='http://www.w3.org/2001/XMLSchema'>
namespace='http://www.w3.org/2009/09/ws-tra'
schemaLocation='http://www.w3.org/2009/09/ws-tra/transfer.xsd'
<wsdl:message
name='GetMessage'>
<wsdl:part name='Body' element='tns:Get'/>
<wsdl:message
name='GetResponseMessage'>
<wsdl:part name='Body' element='tns:GetResponse'/>
<wsdl:message
name='PutMessage'>
<wsdl:part name='Body' element='tns:Put'/>
<wsdl:message
name='PutResponseMessage'>
<wsdl:part name='Body' element='tns:PutResponse'/>
<wsdl:message
name='DeleteMessage'>
<wsdl:part name='Body' element='tns:Delete'/>
<wsdl:message
name='DeleteResponseMessage'>
<wsdl:part name='Body' element='tns:DeleteResponse'/>
<wsdl:message
name='CreateMessage'>
<wsdl:part name='Body' element='tns:Create'/>
<wsdl:message
name='CreateResponseMessage'>
<wsdl:part name='Body' element='tns:CreateResponse'/>
<wsdl:portType
name='Resource'>
This port type
defines a resource that can be read,
wsam:Action='http://www.w3.org/2009/09/ws-tra/Get'/>
message='tns:GetResponseMessage'
wsam:Action='http://www.w3.org/2009/09/ws-tra/GetResponse'
/>
wsam:Action='http://www.w3.org/2009/09/ws-tra/Put'
/>
message='tns:PutResponseMessage'
wsam:Action='http://www.w3.org/2009/09/ws-tra/PutResponse'
/>
<wsdl:operation name='Delete'>
wsam:Action='http://www.w3.org/2009/09/ws-tra/Delete'
/>
message='tns:DeleteResponseMessage'
wsam:Action='http://www.w3.org/2009/09/ws-tra/DeleteResponse'
/>
<wsdl:portType
name='ResourceFactory'>
This port type
defines a Web service that can create new
<wsdl:operation name='Create'>
wsam:Action='http://www.w3.org/2009/09/ws-tra/Create'
/>
message='tns:CreateResponseMessage'
wsam:Action='http://www.w3.org/2009/09/ws-tra/CreateResponse'
/>