2 Introduction
There are numerous applications for which a
simple single-request/single-reply metaphor is insufficient for
transferring large data sets over SOAP. Applications that do not
fit into this simple paradigm include streaming, traversal, query,
and enumeration.
This specification defines a simple SOAP-based
protocol for enumeration that allows the data source to provide a
session abstraction, called an enumeration context, to a consumer
that represents a logical cursor through a sequence of data items.
The consumer can then request XML element information items using
this enumeration context over the span of one or more SOAP
messages.
Somewhere, state MUST be maintained regarding
the progress of the iteration. This state MAY be maintained between
requests by the data source being enumerated or by the data
consumer. WS-Enumeration allows the data source to decide, on a
request-by-request basis, which party will be responsible for
maintaining this state for the next request.
In its simplest form, WS-Enumeration defines an operation, Enumerate,
used to establish the creation of an enumeration session or
which allows a data source, in the context
of a specific enumeration, to produce a sequence of XML elements in
the body of a SOAP message. Each subsequent Enumerate operation returns
the next N elements in the aggregate sequence.
A data source MAY provide a custom mechanism for
starting a new enumeration. For instance, a data source that
provides access to a SQL database can support a SELECT operation
that performs a database query and uses an explicit database cursor
to iterate through the returned rows. In general, however, it is
simpler if all data sources support a single, standard operation to
start an enumeration. This specification mandates
that data sources MUST implement the Enumerate operation for starting a new
enumeration of a data source.
Each new enumeration results in a distinct enumeration context,
each with its own logical cursor/position.
Note that different
enumerations of the same data source can produce different results;
this can happen even for two enumeration contexts created
concurrently by a single consumer using identical Enumerate
requests. The ordering or completeness of the enumeration
is undefined; the returned data items represent a selection by the
data source of items it wishes to present to that consumer at that
time in that order, with no guarantee that every available item is
returned or that the order in which items is returned has any
semantic meaning whatsoever (of course, any specific data source
can provide strong guarantees, if so desired). In particular,
note that the very act of enumerating the contents of a
data source can modify the contents of the data source; for
instance, a queue might be represented as a data source such that
items that are returned in a Enumerate response are removed from the
queue.
2.1 Requirements
This specification intends to meet the following requirements:
Support enumeration of data sources
that cannot practically fit into a single SOAP
message.
Support both server-side and
client-side enumeration state maintenance.
Minimize additional mechanism
beyond the current web service architecture.
3 Notations and Terminology
This section specifies the notations,
namespaces, and terminology used in this
specification.
3.1 Notational Conventions
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 normative outlines for messages:
The syntax appears as an XML
instance, but values in italics indicate data types instead of
values.
Characters are appended to elements
and attributes to indicate cardinality:
"?" (0 or 1)
"*" (0 or more)
"+" (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 3-1) 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
further 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 service MAY choose
not to transmit the fault.
3.2 Considerations on the Use of Extensibility Points
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
Enumeration namespace URI.
3.3 Terminology
- Consumer
The Web service that is requesting the data
enumeration from the data source
- Data Source
A Web service that supports traversal using
enumeration contexts via the Enumerate operation defined in this
specification
- Enumeration context
A session context that represents a specific
traversal through a logical sequence of XML element information
items using the Enumerate operation defined in this
specification
3.4 Compliance
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 3.5 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 conform to the
WS-Addressing specifications and 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.
Implementations are expected to support both UTF-8 and UTF-16 as
described in XML 1.0.
Implementations of this specification MUST conform to the corrected
version of WSDL as defined by the 'WSDL Correction' sections of WS-I
Basic Profile 1.2 [BP12] and WS-I Basic Profile 2.0
[BP20].
3.5 XML Namespaces
The XML namespace URI that MUST be used by
implementations of this specification is:
Table 3-1 lists XML namespaces that are used in
this specification. The choice of any namespace prefix is arbitrary
and not semantically significant.
The working group intends to update the value of the Web Services
Enumeration 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 Enumeration 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
.
4 Enumeration Messages
Enumeration contexts represent a specific
traversal through a sequence of XML information items. A Enumerate
operation can be used to establish an enumeration context from a
data source. A subsequent Enumerate operation is used to fetch information
items from a data source according to a specific enumeration context. A
Release operation is used to tell a data source that the consumer
is abandoning an enumeration context before it has completed the
enumeration.
Enumeration contexts are represented as XML data
that is opaque to the consumer. Initially, the consumer gets an
enumeration context from the data source by means of a Enumerate
operation. The consumer then passes that XML data back to the data
source in subsequent Enumerate requests. Optionally, the data source MAY
return an updated enumeration context in the Enumerate response; when
present, this new enumeration context MUST replace the old one on the
consumer, and MUST be passed to the data source in all future
requests until and unless the data source again returns an updated
enumeration context.
Callers MAY issue a Release operation against a
valid enumeration context at any time, which causes the enumeration
context to become invalid and allows the data source to free up any
resources it might have allocated to the enumeration. Issuing a
Release operation prior to reaching the end of the sequence of
items is explicitly allowed; however, no further operations
MUST be issued after a Release.
An enumeration context can become invalid for any reason including:
Enumeration completed (i.e. an EndOfSequence has been returned in a
Enumerate response)
Enumeration released
Enumeration expired
Enumeration context replaced in the response to another Enumerate request
Enumeration ended (i.e. as indicated via an EnumerationEnd message from
data source)
As the last item indicates, the data source MAY invalidate an
enumeration context at any time.
When processing a Enumerate, Renew, GetStatus or Release operation, a
data source MUST generate an wsen:InvalidEnumerationContext fault if
it determines that the enumeration context supplied by the consumer
in the request is invalid.
Note that the data source might not be able to determine that an
enumeration context is invalid, especially if all of the state
associated with the enumeration is kept in the enumeration context
and refreshed on every EnumerateResponse or RenewResponse.
Once a consumer determines that an enumeration context is invalid, it
MUST NOT issue any more WS-Enumeration request messages referencing
that enumeration context.
4.1 Enumerate
The Enumerate operation is initiated by sending a Enumerate request
message to the data source.
This operation MUST be supported by compliant data sources.
The Enumerate request message MUST be of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/Enumerate
[Body]
<wsen:Enumerate ...>
( <wsen:NewContext ...>
<wsen:EndTo>endpoint-reference</wsen:EndTo> ?
<wsen:Expires BestEffort="xs:boolean"? ...>
(xs:dateTime | xs:duration)
</wsen:Expires> ?
<wsen:Filter Dialect="xs:anyURI"?> xs:any </wsen:Filter> ?
xs:any*
</wsen:NewContext> |
<wsen:EnumerationContext ...>...</wsen:EnumerationContext> )
<wsen:MaxTime>xs:duration</wsen:MaxTime> ?
<wsen:MaxItems>xs:long</wsen:MaxItems> ?
<wsen:MaxCharacters>xs:long</wsen:MaxCharacters> ?
xs:any*
</wsen:Enumerate>
The following describes additional, normative
constraints on the outline listed above:
- [Body]/wsen:Enumerate/wsen:NewContext
This OPTIONAL element contains the information necessary to create
a new Enumeration.
Note, a Enumerate request MUST have either a wsen:EnumerationContext
element or a wsen:NewContext element.
- [Body]/wsen:Enumerate/wsen:NewContext/wsen:EndTo
This OPTIONAL element denotes where to send
an EnumerationEnd message if the enumeration is terminated
unexpectedly
(see 4.5 EnumerationEnd).
If present, this element MUST
be of type wsa:EndpointReferenceType. Default is to not send this
message. The endpoint to which the EndTo EPR
refers MUST support the EnumerationEndPortType portType.
Unless some mechanism is used to indicate otherwise, the messages
sent to this endpoint MUST use the same version of SOAP that was
used for the Enumerate message.
If the data source does not support the use of the EndTo EPR,
the data source MUST generate a wsen:EndToNotSupported fault.
If included within the Enumerate request message, the
wsen:EndTo SHOULD have some cursory validity checking performed before
the Enumerate response is returned. While not all errors can be detected
prior to sending a message to that EPR, some obvious ones can be
detected. For example, an unsupported transport specified within the
wsa:Address IRI.
Detecting these errors during Enumerate processing will lessen the
chances of the consumer creating an unusable enumeration. If this
check is performed and a problem is detected then the data source
MUST generate a wsen:UnusableEPR fault rather than returning the
EnumerateResponse
message.
- [Body]/wsen:Enumerate/wsen:NewContext/wsen:Expires
This OPTIONAL element can be used by the consumer to indicate the
expiration time of the requested enumeration.
A value of PT0S indicates a request for an infinite expiration time
(i.e. an enumeration that never expires).
The absence of the wsen:Expires element indicates that the expiration
value will be chosen by the data source.
This value is communicated via the wsen:GrantedExpires element
(see below).
If the wsen:Expires element is present and the data source is not
able to grant an expiration time that matches the specified value
then it MUST generate a wsen:UnsupportedExpirationValue fault.
The value of the wsen:Expires element MAY be either a duration
(xs:duration) or a specific time (xs:dateTime). Data sources
MUST accept duration values and MAY
accept specific time values. Upon receiving a request that
contains specific time values, a data source
that does not support such value types MUST fail the
request and generate a wsen:UnsupportedExpirationType fault.
If a consumer chooses to use specific time values in a request,
it is RECOMMENDED that these values include a time zone component.
Specific time values that lack a time zone MUST be interpreted in
the local time zone of the receiver.
- [Body]/wsen:Enumerate/wsen:NewContext/wsen:Expires@BestEffort
This OPTIONAL attribute, when present with a value of 'true',
indicates that the data source MUST grant an expiration time that
is its best effort to match the requested
expiration time. Default value of this attribute is "false" in
which case the data source MUST grant the requested expiration time
or fault the enumeration request as defined above.
- [Body]/wsen:Enumerate/wsen:NewContext/wsen:Filter
This OPTIONAL element contains a Boolean
predicate in some dialect (see [ [Body]/wsen:Enumerate/wsen:NewContext/wsen:Filter/@Dialect ])
that all items of
interest MUST satisfy. The resultant enumeration context MUST NOT
return items for which this predicate expression evaluates to
the value false. If this element is absent, then the implied value
is the expression true(), indicating that no filtering is
desired.
If the data source does not support
filtering, the request MUST fail, and the data source MUST generate
a wsen:FilteringNotSupported fault.
If the data source supports filtering but
cannot honor the requested filter dialect, the request MUST fail,
and the data source MUST generate a
wsen:FilterDialectRequestedUnavailable fault.
If the data source supports filtering and the
requested dialect but cannot process the requested filter content,
the request MUST fail, and the data source MUST generate a
wsen:CannotProcessFilter fault.
It is possible for a Enumerate request to contain a filter that
will never evaluate to true for the lifetime of the enumeration.
If a data source detects this condition during the processing
of the Enumerate request it MUST generate a
wsen:EmptyFilter fault in response to the Enumerate request message.
If, after the EnumerateResponse message has been sent, the
data source determines that the filter will never evaluate to true
for the lifetime of the enumeration, or if there is an error within
the filter expression, the enumeration MUST be terminated. In this
case if an EndTo was provided, then a EnumerationEnd message MUST
be sent with a Reason value of
"http://www.w3.org/2011/03/ws-evt/SourceCancelling".
- [Body]/wsen:Enumerate/wsen:NewContext/wsen:Filter/@Dialect
Implied value is
"http://www.w3.org/2011/03/ws-enu/Dialects/XPath10".
If filtering is supported, then support for the XPath 1.0 dialect
(described below) is RECOMMENDED.
Alternate filter dialects can be defined.
Such dialect definitions MUST include sufficient information for
proper application. For example, it would need to define the context
(which data) over which the filter operates.
- [Body]/wsen:Enumerate/wsen:NewContext/wsen:Filter/@Dialect="
http://www.w3.org/2011/03/ws-enu/Dialects/XPath10
Value of [Body]/wsen:Enumerate/wsen:NewContext/wsen:Filter is
an XPath [XPath1.0]
predicate expression (PredicateExpr); the context
of the expression is:
Context Node: any XML element that
could be returned as a direct child of the wsen:Items
element.
Context Position: 1.
Context Size: 1.
Variable Bindings: None.
Function Libraries: Core Function
Library [XPath1.0].
Namespace Declarations: The
[in-scope namespaces] property [XML Infoset]
of [Body]/wsen:Enumerate/wsen:NewContext/wsen:Filter.
The namespace bindings are evaluated against any namespace
declarations that are in scope where the XPath expression appears
within the SOAP message.
Note that the evaluation of expressions that rely on such context
dependent bindings is fragile in the face of transformations that alter
namespace prefixes. Such transformations might occur during the
transmission, processing, storage, or retrieval of a request. Clients
that wish to isolate expressions from the effects of any changes to the
namespace prefixes in the containing SOAP message are advised to
construct expressions in a manner that avoids the use of namespace
prefixes. For example, use an expression such as
"/*[local-name()='a' and namespace-uri()='http://www.example.com']"
not "/ns1:a".
- [Body]/wsen:Enumerate/wsen:NewContext/wsen:Filter/@Dialect="
http://www.w3.org/2011/03/ws-enu/Dialects/XPath20
This filter dialect is the same as the XPath 1.0 filter dialect
except that it uses [XPath2.0] instead of XPath 1.0
as the expression language.
- [Body]/wsen:Enumerate/wsen:EnumerationContext
This OPTIONAL element contains the XML data
that represents the current enumeration context.
Note, a Enumerate request MUST have either a wsen:EnumerationContext
element or a wsen:NewContext element.
- [Body]/wsen:Enumerate/wsen:MaxTime
This OPTIONAL element (of type xs:duration)
indicates the maximum amount of time the consumer is willing to
allow the data source to assemble the Enumerate response. When this
element is absent, the data source is NOT REQUIRED to limit the
amount of time it takes to assemble the Enumerate
response. The data source MUST recognize the wsen:MaxTime
element. If no items
are available prior to the request message's deadline,
the data source MUST return an EnumerationResponse message
that contains a wsen:Items element with no child elements present.
This is useful with data sources that
accumulate items over time and package them into a single Enumerate
response.
- [Body]/wsen:Enumerate/wsen:MaxItems
This OPTIONAL element (of type xs:long)
indicates the number of items (child elements of wsen:Items in the
Enumerate response) the consumer is willing to accept. When this element
is absent, its implied value is 1. Implementations MUST NOT return
more than this number of items in the Enumerate response message.
Implementations MAY return fewer than this number based on either
the wsen:MaxTime timeout, the wsen:MaxCharacters size limit, or
implementation-specific constraints.
Note that a value of zero MAY, along with a wsen:NewContext element,
be used to create a new enumeration without retrieving any of
the data items.
If the data source does not support returning items in response
to a Enumerate request that also created a new enumeration, and the
Enumerate request did not include a wsen:MaxItems with a
value of zero, then the data source MUST generate a
wsen:MaxItemsMustBeZero fault.
- [Body]/wsen:Enumerate/wsen:MaxCharacters
This OPTIONAL element (of type xs:long)
indicates the maximum size of the returned items, in Unicode
characters, that the consumer is willing to accept. When this
element is absent, the data source is NOT REQUIRED to limit the
number of characters in the Enumerate response.
Implementations MUST NOT
return a Enumerate response message whose wsen:Items element, and
all of its children, is larger than MaxCharacters.
Implementations MAY return a smaller message
based on the wsen:MaxTime timeout, the wsen:MaxItems limit, or
implementation-specific constraints.
Even if a Enumerate request contains a
MaxCharacters element, the consumer MUST be prepared to receive a
Enumerate response that contains more data characters than specified, as
XML canonicalization or alternate XML serialization algorithms can
change the size of the representation.
When compiling the list of items to return, if the next item would
cause the wsen:Items array to be larger than the MaxCharacters
value and the wsen:Items array is not empty then the data source
MUST return the current list of items back to the client, saving
that next item for a subsequent enumerate request. If, however,
the wsen:Items array is empty the data source MUST skip the item
and MUST NOT return it as part of the enumeration.
Other components of the outline above are not
further constrained by this specification.
Upon successful processing of a Enumerate request
message, a data source MUST return a Enumerate response
message of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/EnumerateResponse
[Body]
<wsen:EnumerateResponse ...>
<wsen:GrantedExpires ...>
(xs:dateTime | xs:duration)
</wsen:GrantedExpires>
<wsen:EnumerationContext ...>...</wsen:EnumerationContext> ?
<wsen:Items Reason="xs:anyURI"?>
<xs:any> enumeration-specific element </xs:any> *
</wsen:Items> ?
<wsen:EndOfSequence/> ?
xs:any*
</wsen:EnumerateResponse>
The following describes additional, normative
constraints on the outline listed above:
- [Body]/wsen:EnumerateResponse/wsen:GrantedExpires
This element is the expiration time assigned by the data source. The
expiration time MAY be either a specific time or a duration
but MUST be of the same type as the wsen:Expires element of
the corresponding request. If the corresponding request
did not contain a wsen:Expires element, this element MUST be
a duration (xs:duration).
When expressed as a duration, the wse:GrantedExpires element
designates the amount of time remaining on this enumeration
as measured from the moment the request message was processed.
Although this specification cannot dictate when, during the
processing of a request message a enumeration's remaining time
is determined, the data source MUST measure the expiration
duration from a time that is at or before the transmission of
the response message.
A wsen:GrantedExpires value of PT0S indicates that the enumeration will
never expire.
It will terminate when the end of the
enumeration is reached, or if the consumer sends a Release request,
or by the data source at any time for reasons such as connection
termination, resource constraints, or system
shut-down.
Note that a wsen:GrantedExpires element MUST only appear in a
EnumerateResponse message if the corresponding Enumerate request
message included a wsen:NewContext element.
-
[Body]/wsen:EnumerateResponse/wsen:EnumerationContext
The OPTIONAL EnumerationContext element, if
present, contains a XML representation of the
enumeration context. The consumer MUST replace the prior
representation, if any, with the contents of this element.
-
[Body]/wsen:EnumerateResponse/wsen:Items/xs:any
The OPTIONAL Items element contains zero or
more enumeration-specific elements, one for each item being
returned.
-
[Body]/wsen:EnumerateResponse/wsen:Items/@Reason
Implied value is "http://www.w3.org/2011/03/ws-enu/TimedOut".
The OPTIONAL Reason attribute indicates the reason that the
wsen:Items element has no child elements. Alternate Reason
values can be defined. The Reason attribute MUST NOT be present
if the wsen:Items element has one or more child elements.
-
[Body]/wsen:EnumerateResponse/wsen:Items/@Reason="http://www.w3.org/2011/03/ws-enu/TimedOut"
This value MUST be used if no items are available prior to the
Enumeration request message's deadline.
- [Body]/wsen:EnumerateResponse/wsen:EndOfSequence
This OPTIONAL element indicates that no more
items are available from this enumeration and the enumeration
context sent by the consumer in the request becomes invalid.
Note that at least one of wsen:Items or
wsen:EndOfSequence MUST appear. It is possible for both to appear
if items are returned and the sequence is exhausted. Similarly,
wsen:EnumerationContext and wsen:EndOfSequence MUST NOT both
appear; neither can appear, or one without the other, but not both
in the same EnumerateResponse.
Example 4-1 lists a sample Enumerate request that
establishes a new context.
(01) <s:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
(02) xmlns:wsa="http://www.w3.org/2005/08/addressing"
(03) xmlns:wsen="http://www.w3.org/2011/03/ws-enu">
(04) <s:Header>
(05) <wsa:Action>
(06) http://www.w3.org/2011/03/ws-enu/Enumerate
(07) </wsa:Action>
(08) <wsa:MessageID>
(09) urn:uuid:e7c5726b-de29-4313-b4d4-b3425b200839
(10) </wsa:MessageID>
(11) <wsa:To>http://www.example.com/relayAgent/enum19</wsa:To>
(12) <wsa:ReplyTo>
(13) <wsa:Address>
(14) http://www.w3.org/2005/08/addressing/anonymous
(15) </wsa:Address>
(16) </wsa:ReplyTo>
(17) </s:Header>
(18) <s:Body>
(19) <wsen:Enumerate>
(20) <wsen:NewContext>
(21) <wsen:Expires> PT10M </wsen:Expires>
(22) </wsen:NewContext>
(23) <wsen:MaxItems> 0 </wsen:MaxItems>
(24) </wsen:Enumerate>
(25) </s:Body>
(26) </s:Envelope>
Lines (05-07) in Example 4-1 indicate this message
is a Enumerate request and that the data source is expected to
respond with a Enumerate response message. The wsen:Expires
element on line (21) indicates that the consumer would like an
enumeration context that will be good for 10 minutes.
No wsen:Filter element is present, so the resultant
enumeration context is expected to return all available
items. Line (23) indicates that the Enumerate response
is not to include any items from the enumeration - this operation
is just estalishing the enumeration context.
Example 4-2 lists a response to the request in
Example 4-1.
(01) <s:Envelope xmlns:S='http://www.w3.org/2003/05/soap-envelope'
(02) xmlns:wsen='http://www.w3.org/2011/03/ws-enu'
(03) xmlns:wsa='http://www.w3.org/2005/08/addressing'>
(04) <s:Header>
(05) <wsa:Action>
(06) http://www.w3.org/2011/03/ws-enu/EnumerateResponse
(07) </wsa:Action>
(08) <wsa:RelatesTo>
(09) urn:uuid:e7c5726b-de29-4313-b4d4-b3425b200839
(10) </wsa:RelatesTo>
(11) <wsa:To>
(12) http://www.w3.org/2005/08/addressing/anonymous
(13) <wsa:To>
(14) </s:Header>
(15) <s:Body>
(16) <wsen:EnumerateResponse>
(17) <wsen:GrantedExpires> PT10M </wsen:GrantedExpires>
(18) <wsen:EnumerationContext>
(19) 123
(20) </wsen:EnumerationContext>
(21) </wsen:EnumerateResponse>
(22) </s:Body>
(23) </s:Envelope>
Lines (05-07) in Example 4-2 indicate this message
is a Enumerate response message. Line (17) indicates that the data
source has created an enumeration context with a lifetime
of 10 minutes. Lines (18-20) are the XML representation of the
enumeration context that supports the Enumerate operation defined
below.
Example 4-3 lists a Enumerate request that uses the
enumeration context established in the previous example.
(01) <s:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
(02) xmlns:wsa="http://www.w3.org/2005/08/addressing"
(03) xmlns:wsen="http://www.w3.org/2011/03/ws-enu">
(04) <s:Header>
(05) <wsa:Action>
(06) http://www.w3.org/2011/03/ws-enu/Enumerate
(07) </wsa:Action>
(08) <wsa:MessageID>
(09) urn:uuid:e7c5726b-de29-4313-b4d4-b3425b200839
(10) </wsa:MessageID>
(11) <wsa:To>http://www.example.com/relayAgent</wsa:To>
(12) <wsa:ReplyTo>
(13) <wsa:Address>
(14) http://www.w3.org/2005/08/addressing/anonymous
(15) </wsa:Address>
(16) </wsa:ReplyTo>
(17) </s:Header>
(18) <s:Body>
(19) <wsen:Enumerate>
(20) <wsen:EnumerationContext>123</wsen:EnumerationContext>
(21) <wsen:MaxTime>P30S</wsen:MaxTime>
(22) <wsen:MaxItems>10</wsen:MaxItems>
(23) </wsen:Enumerate>
(24) </s:Body>
(25) </s:Envelope>
Lines (05-07) in Example 4-3 indicate this message
is a Enumerate request and that the data source is expected to respond
with a Enumerate response message. Line (21) indicates that the response
message SHOULD be generated no more than 30 seconds after receipt
of the Enumerate request message. Line (22) indicates that no more than
10 items can be returned in the body of the Enumerate response
message.
Example 4-4 lists a response to the request in
Example 4-3.
(01) <s:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
(02) xmlns:wsen="http://www.w3.org/2011/03/ws-enu"
(03) xmlns:wsa="http://www.w3.org/2005/08/addressing">
(04) <s:Header>
(05) <wsa:Action>
(06) http://www.w3.org/2011/03/ws-enu/EnumerateResponse
(07) </wsa:Action>
(08) <wsa:RelatesTo>
(09) urn:uuid:e7c5726b-de29-4313-b4d4-b3425b200839
(10) </wsa:RelatesTo>
(11) <wsa:To>
(12) http://www.w3.org/2005/08/addressing/anonymous
(13) <wsa:To>
(14) </s:Header>
(15) <s:Body>
(16) <wsen:EnumerateResponse>
(17) <wsen:Items xmlns:xx="http://fabrikam123.example.com/schema/log">
(18) <xx:LogEntry id="1">System booted</xx:LogEntry>
(19) <xx:LogEntry id="2">AppX started</xx:LogEntry>
(20) <xx:LogEntry id="3">John Smith logged on</xx:LogEntry>
(21) <xx:LogEntry id="4">AppY started</xx:LogEntry>
(22) <xx:LogEntry id="5">AppX crashed</xx:LogEntry>
(23) </wsen:Items>
(24) <wsen:EndOfSequence/>
(25) </wsen:EnumerateResponse>
(26) </s:Body>
(27) </s:Envelope>
Lines (05-07) in Example 4-4 indicate this message
is a Enumerate response message. Lines (18-22) are the five items
returned by this Enumerate request. The presence of a wsen:EndOfSequence
element (line (24)) indicates that no more items are available
and that the enumeration context is now invalid.
4.2 Renew
To update, or renew, the expiration for an enumeration, a Renew
request message is sent to the data source.
This operation MUST be supported by compliant data sources.
The Renew request message MUST be of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/Renew
[Body]
<wsen:Renew ...>
<wsen:EnumerationContext ...>...</wsen:EnumerationContext>
<wsen:Expires BestEffort="xs:boolean"? ...>
(xs:dateTime | xs:duration)
</wsen:Expires> ?
xs:any*
</wsen:Renew>
Components of the outline listed above are
additionally constrained as for a request to create an enumeration
(see 4.1 Enumerate) with the following
addition(s):
- [Body]/wsen:Renew/wsen:EnumerationContext
This REQUIRED element contains the XML data
that represents the current enumeration context.
Other components of the outline above are not
further constrained by this specification.
If the data source accepts a request to renew an
enumeration, it MUST reply with a response of the following
form:
[Action]
http://www.w3.org/2011/03/ws-enu/RenewResponse
[Body]
<wsen:RenewResponse ...>
<wsen:GrantedExpires ...>
(xs:dateTime | xs:duration)
</wsen:GrantedExpires> ?
<wsen:EnumerationContext ...>...</wsen:EnumerationContext> ?
xs:any*
</wsen:RenewResponse>
Components of the outline listed above are
constrained as for a response to a Enumerate request
(see 4.1 Enumerate) with the following addition:
-
[Body]/wsen:RenewResponse/wsen:EnumerationContext
This element is OPTIONAL in this response.
If the data source chooses not to renew this enumeration, the request
MUST fail, and the data source MUST generate a SOAP 1.1 Server fault
or a SOAP 1.2 Receiver fault indicating that the renewal was not
accepted.
Other components of the outline above are not
further constrained by this specification.
4.3 GetStatus
To get the status of an enumeration, the
consumer sends a GetStatus request message to the data source.
This operation MUST be supported by compliant data sources.
The message MUST be of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/GetStatus
[Body]
<wsen:GetStatus ...>
<wsen:EnumerationContext ...>...</wsen:EnumerationContext>
xs:any*
</wsen:GetStatus>
Components of the outline listed above are
additionally constrained as for a request to renew an enumeration
(see 4.2 Renew). Other components of the outline above are
not further constrained by this specification.
If the enumeration is valid the data source MUST reply with a
response of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/GetStatusResponse
[Body]
<wsen:GetStatusResponse ...>
<wsen:GrantedExpires ...>
(xs:dateTime | xs:duration)
</wsen:GrantedExpires> ?
xs:any*
</wsen:GetStatusResponse>
Components of the outline listed above are
constrained as for a response to a renew request
(see 4.2 Renew). 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 consumer. This means that in case of an underlying
protocol error that might get unnoticed, resending the same request
can be done automatically.
4.4 Release
The Release operation is initiated by sending a
Release request message to the data source.
This operation MUST be supported by compliant data sources.
The Release request message MUST be of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/Release
[Body]
<wsen:Release ...>
<wsen:EnumerationContext ...>...</wsen:EnumerationContext>
xs:any*
</wsen:Release>
The following describes additional, normative
constraints on the outline listed above:
-
[Body]/wsen:Release/wsen:EnumerationContext
This REQUIRED element contains the XML data
that represents the enumeration context being
abandoned.
Other components of the outline above are not
further constrained by this specification.
Upon successful processing of a Release request
message, a data source MUST return a Release response
message of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/ReleaseResponse
[Body]
<wsen:ReleaseResponse ...>
xs:any*
</wsen:ReleaseResponse>
Example 4-5 lists a Release request.
(01) <s:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
(02) xmlns:wsa="http://www.w3.org/2005/08/addressing"
(03) xmlns:wsen="http://www.w3.org/2011/03/ws-enu">
(04) <s:Header>
(05) <wsa:Action>
(06) http://www.w3.org/2011/03/ws-enu/Release
(07) </wsa:Action>
(08) <wsa:MessageID>
(09) urn:uuid:e7c5726b-de29-4313-b4d4-b3425b200839
(10) </wsa:MessageID>
(11) <wsa:To>http://www.example.com/relayAgent</wsa:To>
(12) <wsa:ReplyTo>
(13) <wsa:Address>
(14) http://www.w3.org/2005/08/addressing/anonymous
(15) </wsa:Address>
(16) </wsa:ReplyTo>
(17) </s:Header>
(18) <s:Body>
(19) <wsen:Release>
(20) <wsen:EnumerationContext>123</wsen:EnumerationContext>
(21) </wsen:Release>
(22) </s:Body>
(23) </s:Envelope>
Lines (05-07) in Example 4-5 indicate this message
is a Release request.
Line (20) identifies the enumeration context to be released.
Example 4-6 lists a response to the request in
Example 4-5.
(01) <s:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
(02) xmlns:wsen="http://www.w3.org/2011/03/ws-enu"
(03) xmlns:wsa="http://www.w3.org/2005/08/addressing">
(04) <s:Header>
(05) <wsa:Action>
(06) http://www.w3.org/2011/03/ws-enu/ReleaseResponse
(07) </wsa:Action>
(08) <wsa:RelatesTo>
(09) urn:uuid:e7c5726b-de29-4313-b4d4-b3425b200839
(10) </wsa:RelatesTo>
(11) <wsa:To>
(12) http://www.w3.org/2005/08/addressing/anonymous
(13) <wsa:To>
(14) </s:Header>
(15) <s:Body>
(16) <wsen:ReleaseResponse/>
(17) </s:Body>
(18) </s:Envelope>
Lines (05-07) in Example 4-6 indicate this message
is a Release response message.
4.5 EnumerationEnd
If the data source terminates an enumeration unexpectedly, and it
supports the use of the EndTo EPR, and the EndTo EPR was present in the
Enumerate message for that enumeration (see 4.1 Enumerate),
the EnumerationEnd message MUST be sent to the endpoint reference
indicated by that EPR.
Note, a enumeration context expiring as expected is not considered to
be an unexpected termination, therefore a EnumerationEnd message MUST NOT
be sent in this case.
The message MUST be of the following form:
[Action]
http://www.w3.org/2011/03/ws-enu/EnumerationEnd
[Body]
<wsen:EnumerationEnd ...>
<wsen:Code>
( http://www.w3.org/2011/03/ws-enu/SourceShuttingDown |
http://www.w3.org/2011/03/ws-enu/SourceCancelling |
xs:anyURI )
</wsen:Code>
<wsen:Reason xml:lang="language identifier" >
xs:string
</wsen:Reason> ?
xs:any*
</wsen:EnumerationEnd>
The following describes additional, normative
constraints on the outline listed above:
-
[Body]/wsen:EnumerationEnd/wsen:Code =
"http://www.w3.org/2011/03/ws-enu/SourceShuttingDown"
This value MUST be used if the data source
terminated the enumeration because the source is being shut down in
a controlled manner; that is, if the data source is being shut down
but has the opportunity to send an EnumerationEnd message before it
exits.
-
[Body]/wsen:EnumerationEnd/wsen:Code =
"http://www.w3.org/2011/03/ws-enu/SourceCancelling"
This value MUST be used if the data source
terminated the enumeration for some other reason before it
expired.
- [Body]/wsen:EnumerationEnd/wsen:Reason
This OPTIONAL element contains text, in the
language specified by the @xml:lang attribute, describing the
reason for the unexpected enumeration termination.
Other components of the outline above are not
further constrained by this specification.
5 Faults
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.
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>
<s12:Header>
<wsa:Action> [Action] </wsa:Action>
<!-- Headers elided for brevity. -->
</s12:Header>
<s11:Body>
<s11:Fault>
<faultcode>[Subcode]</faultcode>
<faultstring xml:lang="en">[Reason]</faultstring>
<detail>
[Detail]
...
</detail>
</s11:Fault>
</s11:Body>
</s11:Envelope>
5.1 UnsupportedExpirationValue
This fault MUST be generated when a request specifies an
expiration that is not within the min/max range.
| [Code] | s12:Sender |
| [Subcode] | wsen:UnsupportedExpirationValue |
| [Reason] |
The expiration time requested is not within the min/max range.
|
| [Detail] | |
5.2 UnsupportedExpirationType
This fault MUST be generated when a request specifies an
expiration time and the data source is only capable of accepting
expiration durations; for instance, if the data source does not
have access to absolute time.
| [Code] | s12:Sender |
| [Subcode] | wsen:UnsupportedExpirationType |
| [Reason] | Only expiration durations are supported. |
| [Detail] | |
5.3 FilteringNotSupported
This fault MUST generated when the data source does not support filters.
| [Code] | s12:Sender |
| [Subcode] | wsen:FilteringNotSupported |
| [Reason] |
Filtering not supported.
|
| [Detail] | |
5.4 FilterDialectRequestedUnavailable
This fault MUST be generated when the data source does not support
the requested filter dialect.
| [Code] | s12:Sender |
| [Subcode] | wsen:FilterDialectRequestedUnavailable |
| [Reason] |
Filter dialect requested unavailable.
|
| [Detail] |
<wsen:SupportedDialect> +
OPTIONAL; repeating; one per filter dialect supported by the
receiver
|
5.5 CannotProcessFilter
This fault MUST be generated when the data source can not process the
filter content.
| [Code] | s12:Sender |
| [Subcode] | wsen:CannotProcessFilter |
| [Reason] |
Cannot filter as requested.
|
| [Detail] | |
5.6 InvalidEnumerationContext
This fault MUST be generated when the enumeration context is invalid.
| [Code] | s12:Receiver |
| [Subcode] | wsen:InvalidEnumerationContext |
| [Reason] |
Text explaining why the enumeration context is no longer valid, or
"Invalid enumeration context"
if no additional information is available.
|
| [Detail] | |
5.7 UnusableEPR
This fault MUST be generated when a data source detects
that the wsen:EndTo EPR is unusable.
| [Code] | s12:Sender |
| [Subcode] | wsen:UnusableEPR |
| [Reason] | The wsen:EndTo EPR is unusable. |
| [Detail] |
Details as to why the EPR is unusable.
|
5.8 EndToNotSupported
This fault MUST be generated by a data source that does not support
/wsen:Enumerate/wsen:NewContext/wsen:EndTo semantics, in response to
a Enumerate request that contains a wsen:EndTo element.
| [Code] | s12:Sender |
| [Subcode] | wsen:EndToNotSupported |
| [Reason] | wsen:EndTo semantics is not supported. |
| [Detail] |
none
|
5.9 EmptyFilter
This fault MUST be generated when a data source detects a
Enumerate request containing a filter that, for whatever
reason, will never evaluate to true.
| [Code] | s12:Sender |
| [Subcode] | wsen:EmptyFilter |
| [Reason] | The wsen:Filter would result in zero data items. |
| [Detail] |
The wsen:Filter value.
|
5.10 MaxItemsMustBeZero
This fault MUST be generated by a data source that does not support
returning items in a Enumerate response and the Enumerate request
did not include a wsen:MaxItems with a value of zero.
| [Code] | s12:Sender |
| [Subcode] | wsen:MaxItemsMustBeZero |
| [Reason] | wsen:MaxItems must be zero when creating a new enumeration. |
| [Detail] |
none
|
6 Security Considerations
This specification considers two sets of security requirements, those
of the applications that use the WS-Enumeration protocol and those of
the protocol itself.
This specification makes no assumptions about the security requirements
of the applications that use WS-Enumeration. However, once those
requirements have been satisfied within a given operational context,
the addition of WS-Enumeration to this operational context can not
undermine the fulfillment of those requirements; the use of
WS-Enumeration SHOULD NOT create additional attack vectors within
an otherwise secure system.
The material below is not a "check list". There are many other security
concerns that need to be considered when implementing or using this
protocol. Implementers and users of this protocol are urged to perform
a security analysis to determine their particular threat profile and
the appropriate responses to those threats.
6.1 Creating Enumeration Contexts
An enumeration represents a logical cursor through a sequence of
data items. If the information in these items is sensitive, it is
advisable to for Data Sources to authenticate and authorize Consumers
as part of the processing of the Enumerate request. Note that a
Data Source might authorize retrievals on a per-item basis after the
enumeration has been created. This might be necessary in cases where
the sensitivity of the information requested might not be known at
the time the Enumerate request is processed or varies during the
lifetime of the enumeration.
6.2 Protecting Enumeration Contexts
Once created, it is advisable to treat Enumeration Contexts as
protected resources. Renew, GetStatus, and Release requests ought to
be authenticated and authorized (for example, the identity of the
requester ought to be checked against the identity of the entity
that performed the original Enumerate request). Likewise
EnumerationEnd messages ought to be authenticated and authorized
(for example, the identity of the sender ought to be checked against
the identity the entity that sent the original EnumerateResponse message).
Note that authentication and authorization policies (i.e. the rules
that define which entities are allowed to perform which requests and
the mechanisms by which the identities of these entities are
discovered and verified) are particular to individual deployments.
Enumeration Contexts are also sensitive because of the way they are
used to maintain or reference the state of active Enumerations.
Attackers able to snoop or guess the value of an Enumeration Context
could use this information to Enumerate data items in that Enumeration.
To defend against the misuse of snooped/guessed Enumeration Contexts,
Data Sources are advised to authenticate and authorize clients
sending Enumerate requests.
6.3 Endpoint Verification
Data Source implementations that perform validity checks on the
EndTo EPR used in the Enumerate request are advised that such checks
can be misused to obtain information about a target network. For
example, suppose a Data Source implementation verifies the address
of EndTo EPRs by attempting to create a connection to this EPR's
address and faulting the Enumerate request if a connection cannot
be created. When deployed within a DMZ, such a Data Source could be
exploited by a malicious Consumer to probe for other, non-visible
hosts by guessing target addresses and using them in Enumerate requests.
Note that, even if the returned fault does not provide connection
information, the time the Data Source spends processing the
Enumerate request might betray the existence or non-existence of a
host at the target address.
Implementations that perform validity checks on the EndTo EPR are
advised to provide a means to disable such checks in environments
where these types of attacks are an issue.
7 WS-Enumeration Metadata
An endpoint MAY indicate its support of WS-Enumeration, or its features,
by including the WS-Enumeration DataSource Policy assertion within its
WSDL. By
doing so the endpoint is indicating that the corresponding WS-Enumeration
operations are supported by that endpoint even though they are implicit
and do not explicitly appear in its WSDL
(i.e. the WS-Enumeration operations do not appear in the WSDL that MAY
be retrievable by using a WS-MetadataExchange GetWSDL to that endpoint).
The WS-Enumeration WSDL containing the operations indicated by the
Enumeration Assertion MAY be exposed by including the WSDL as a child
of the DataSource Policy assertion or by including a reference to it
using the mex:Location or mex:Reference element (as described in
WS-MetadataExchange [WS-MetadataExchange] Section 9).
This WS-Enumeration WSDL can be annotated to indicate any endpoint
specific metadata that might be needed by clients interacting with
the WS-Enumeration operations. For example, the WSDL MAY
have policy assertions
that indicate a particular security mechanism used to protect
the WS-Enumeration operations supported by this endpoint.
7.1 Enumeration Assertion
Services indicate support for the WS-Enumeration's definition of a
data source 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 (wsen:DataSource).
The normative outline of this assertion is:
<wsen:DataSource ...>
<wsen:FilterDialect URI="xs:anyURI" ...>
xs:any*
</wsen:FilterDialect> *
<wsen:DateTimeSupported .../> ?
<wsen:Expires min="xs:duration"? max="xs:duration"? .../> ?
<wsen:MaxTime ...> xs:duration </wsen:MaxTime> ?
<wsen:MaxItems ...> xs:long </wsen:MaxItems> ?
<wsen:MaxCharacters ...> xs:long </wsen:MaxCharacters> ?
<wsen:EndToSupported .../> ?
<wsen:ItemsOnNewContextSupported .../> ?
xs:any*
</wsen:DataSource>
The following describes additional, normative constraints on the
outline listed above:
- /wsen:DataSource
This policy assertion has Endpoint Policy Subject. When present in a
policy alternative, it indicates that the subject is a data source
and the WS-Enumeration protocol MUST
be used when communicating with this endpoint.
- /wsen:DataSource/wsen:FilterDialect
When present, this OPTIONAL parameter indicates support for the
specified Filter Dialect IRI.
- /wsen:DataSource/wsen:FilterDialect/xs:any
This extensibility point allows for additional FilterDialect
specific metadata to be included within the policy assertion. Any
metadata that appears is scoped to the use of the specified
FilterDialect URI.
- /wsen:DataSource/wsen:DateTimeSupported
When present, this OPTIONAL parameter indicates support for
expiration time expressed as specific time (rather than duration).
- /wsen:DataSource/wsen:Expires
When present, this OPTIONAL parameter indicates the minimum and
maximum enumeration expiration times that this endpoint will support.
When the OPTIONAL 'min' attribute is absent then the data source
MUST not impose a lower bound on the accepted Expires values. The
implied default value for the OPTIONAL 'max' attribute is
infinite (or PT0S). In all cases, the 'min' value MUST be less
than or equal to the 'max' value.
- /wsen:DataSource/wsen:MaxTime
When present, this OPTIONAL parameter indicates the maximum MaxTime
value supported by this endpoint.
The implied default is infinite.
Note: a value of "PT0S" indicates that this endpoint supports any
duration value.
- /wsen:DataSource/wsen:MaxItems
When present, this OPTIONAL parameter indicates the maximum
MaxItems value supported by this endpoint. The value specified
MUST be greater than zero.
- /wsen:DataSource/wsen:MaxCharacters
When present, this OPTIONAL parameter indicates the maximum
MaxCharacters value supported by this endpoint. The value specified
MUST be greater than zero.
- /wsen:DataSource/wsen:EndToSupported
When present, this OPTIONAL parameter indicates support for the
/wsen:Enumerate/wsen:NewContext/wsen:EndTo semantics. That is, when a
Enumerate request contains a wsen:EndTo element, a EnumerationEnd
message will be sent to the EPR contained in the wsen:EndTo element,
if the enumeration terminates unexpectedly.
- /wsen:DataSource/wsen:ItemsOnNewContextSupported
When present, this OPTIONAL parameter indicates support for the
Enumerate operation creating a new enumeration context and
returning an initial set of items in the Enumerate response
message. When a data source does not support this feature,
all consumers MUST include a wsen:MaxItems with
a value of zero in Enumerate requests that create new
enumeration contexts.
- /wsen:DataSource/xs:any
This extensibility point allows for additional WS-Enumeration
specific metadata to be included within the policy assertion -
e.g. WS-Enumeration WSDL, or nested policy assertions related to
the WS-Enumeration message exchanges. Any metadata that appears
is scoped to the operations and features of the WS-Enumeration
specification.
8 Acknowledgements
This specification has been developed as a
result of joint work with many individuals and teams,
including:
Alessio Soldano (Red Hat),
Ashok Malhotra (Oracle Corp.),
Asir Vedamuthu (Microsoft Corp.),
Bob Freund (Hitachi, Ltd.),
Bob Natale (MITRE Corp.),
David Snelling (Fujitsu, 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),
Martin Chapman (Oracle Corp.),
Paul Fremantle (WSO2),
Paul Nolan (IBM),
Prasad Yendluri (Software AG),
Ram Jeyaraman (Microsoft Corp.),
Sreedhara Narayanaswamy (CA),
Sumeet Vij (Software AG),
Tom Rutt (Fujitsu, Ltd.),
Vikas Varma (Software AG),
Wu Chou (Avaya Communications),
Yves Lafon (W3C/ERCIM).