Asynchronous request processing

Introduction

This clause describes a light-weight protocol for processing long-running operations asynchronously. Rather than the standard request-response invocation pattern – where a client submits a request and then waits to get the response from the server – an asynchronous request is executed in the background by the server and either a notification message is sent when operation processing has completed or (depending on the conformance classes implemented) the server may be polled periodically to determine the execution status of the request.

The target service implementation for this capability for Testbed 12 is the WFS. However, it is envisioned that the approach described here could apply to a number of OGC services (WCS, CSW, etc.).

For the WFS standard, the following operations may be invoked asynchronously:

  1. GetPropertyValue

  2. GetFeature

  3. GetFeatureWithLock

  4. LockFeature

  5. Transaction

Conformance classes

Two conformance classes are defined for asynchronous request processing:

  1. Asynchronous Processing

  2. Asynchronous Polling

For the Asynchronous Processing conformance class, a server implements the ability to accept an asynchronous request, acknowledge that the request was successfully accepted, process the request in the background and finally send a notification — using the specified response handler — when the request’s processing has been completed. Servers that implement this class may optionally provide a hypermedia control that may be used to cancel the asynchronous request after it has been invoked.

For the Asynchronous Polling conformance class, a server implements the ability to accept an asynchronous request, acknowledge that the request was successfully accepted, process the request in the background and allow the server to be polled periodically to obtain the execution status and progress of the request’s execution. Once request processing has been completed a hypermedia control, provided by the server, will allow the request’s response to be retrieved.

Request semantics

Asynchronous request processing shall be triggered by the presence of the ResponseHandler parameter.

When an operation is invoked asynchronously, the server shall immediately respond with an acknowledgement message (see [AcknowlegementEncoding]) that indicates that the request has been successfully accepted or an exception messages if there was a problem. At this point communication with the server shall terminate.

The server shall then proceed to process the request in the background, taking as much time as necessary to completed its processing.

For servers that implement the Asynchronous Processing class, when request processing has completed a notification message shall be sent using the scheme(s) specified as the value of the ResponseHandler parameter. The content of the notification message is discussed in clause [NotificationMessage].

For servers that implement the Asynchronous Polling class, the acknowledgement message shall contain a means by which the server may be polled to determine the execution status of the request (see [AcknowledgementEncoding]). When request processing has been completed, the acknowledgement message shall contain a means by which the request’s response may be retrieved.

Parameter discussion

The value of the ResponseHandler parameter shall be a list of one or more values. The value of each element of the list shall either be a URI or the token "poll".

If a list element value of the ResponseHandler parameter is a URI, then its form shall be a valid expression of the one the notification schemes that the server claims to support in its capabilities document (see [CapabilitiesResponse]).

This standard does not define a normative set of notification schemes but possible schemes include:

The specific set of schemes supported for each operation shall be advertised in the server’s capabilities document (see [CapabilitiesResponse]).

If a list element value of the ResponseHandler parameter is the token "poll", the server shall, in its acknowledgement message (see [AcknowledgementEncoding]), provide a hypermedia control (see [AsyncPollingSemantics]) that may be used to poll the server periodically to determine the execution status of the request.

If more than one instance of the "poll" token appears as a list element value of the ResponseHandler parameter, the extraneous instances of the token shall be ignored. The "poll" token need only appear once to trigger the inclusion of the status, progress and control elements within the acknowledgement messages (see [AsyncPollingSemantics]).

XML encoding

The following XML-Schema fragment defines the XML-encoding for this parameter:

   <xsd:element name="ResponseHandler" type="xsd:anyUri"/>

KVP encoding

Table 1 defines the KVP-encoding for the ResponseHandler parameter.

Table 1. KVP-encoding for the ResponseHandler parameter
URL Component O/M Description

RESPONSEHANDLER

O

An URI indicating the notification method
Note
 O = Optional, M = Mandatory

Examples

The following example fetches NHD flowlines from the TB12 A007 WFS using an asynchronous XML-encoded GetFeature request:

<?xml version="1.0" ?>
<GetFeature
   version="2.5.0"
   service="WFS"
   xmlns="http://www.opengis.net/wfs/2.5"
   xmlns:fes="http://www.opengis.net/fes/2.5"
   xmlns:gml="http://www.opengis.net/gml/3.2"
   xmlns:cw="http://schemas.cubewerx.com/namespaces/null"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.opengis.net/wfs/2.5
                       http://schemas.cubewerx.com/schemas/wfs/2.5/wfs.xsd
                       http://www.opengis.net/gml/3.2
                       http://schemas.opengis.net/gml/3.2.1/gml.xsd
                       http://schemas.cubewerx.com/namespaces/null
                       http://tb12.cubewerx.com/a007/cubeserv?datastore=USGS&amp;service=WFS&amp;version=2.5&amp;request=DescribeFeatureType&amp;typeNames=NHDFlowline">
   <Query typeNames="cw:NHDFlowline">
      <fes:Filter>
         <fes:BBOX>
            <fes:ValueReference>GEOMETRY</fes:ValueReference>
            <gml:Envelope srsName="http://www.opengis.net/def/crs/epsg/0/4326">
               <gml:lowerCorner>37.709077 -122.513476</gml:lowerCorner>
               <gml:upperCorner>37.839064 -122.351771</gml:upperCorner>
            </gml:Envelope>
         </fes:BBOX>
      </fes:Filter>
   </Query>
   <ResponseHandler>mailto:tb12@pvretano.com</ResponseHandler>
</GetFeature>

The following example fetches NHD flowlines from the TB12 A007 WFS using an asynchronous KVP-encoded GetFeature request:

http://tb12.cubewerx.com/a007/cubeserv?datastore=USGS&
   service=WFS&
   version=2.0.2&
   request=GetFeature&
   typeNames=NHDFlowline&
   count=100&
   outputFormat=application%2Fgml%2Bxml&
   responseHandler=mailto:tb12@pvretano.com&
   bbox=37.709077,-122.513476,37.839064,-122.351771,urn:ogc:def:crs:EPSG::4326
Note
 Examples in this clause may be formatted to facilitate readability as is the case in this example which has been wrapped to highlight the request parameters.

Response

Introduction

This clause defines the XML-Schema of the acknowledgement message that is used to signal that an asynchronous request has been successfully accepted. The same message schema is also used in response to a polling request to indicate the execution status of an asynchronous request.

XML encoding

The following XML-Schema fragment defines the ows:Acknowledgment element:

   <xsd:element name="Acknowledgment"
                type="ows:Acknowledgement" id="Acknowledgement"/>
   <xsd:complexType name="Acknowledgement" id="AcknowledgementType">
      <xsd:sequence>
         <xsd:element ref="atom:link" minOccurs="0" maxOccurs="unbounded"/>
         <xsd:element name="Status"
                      type="wfs:ExecutionStatusType" minOccurs="0"/>
         <xsd:element name="PercentCompleted"
                      type="xsd:nonNegativeInteger" minOccurs="0"/>
      </xsd:sequence>
   </xsd:complexType>

   <xsd:simpleType name="ExecutionStatusType">
      <xsd:union>
         <xsd:simpleType>
            <xsd:restriction base="xsd:string">
               <xsd:enumeration value="cancelled"/>
               <xsd:enumeration value="completed"/>
               <xsd:enumeration value="executing"/>
               <xsd:enumeration value="pending"/>
            </xsd:restriction>
         </xsd:simpleType>
         <xsd:simpleType>
            <xsd:restriction base="xsd:string">
               <xsd:pattern value="other:\w{2,}"/>
            </xsd:restriction>
         </xsd:simpleType>
      </xsd:union>
   </xsd:simpleType>

When an operation is invoked asynchronously, the server shall respond immediately with an ows:Acknowledgment message indicating that the server has successfully accepted the request or an OGC exception message indicating an error. If successfully accepted, the HTTP status code shall be set to "202 Accepted".

Asynchronous Processing class

Response semantics

For servers that implement the Asynchronous Processing conformance class, the ows:Acknowledgment message may contain an atom:link element, with rel="cancel", that may be used to cancel the asynchronously invoked operation.

The response to resolving the rel="cancel" link shall be an ows:Acknowledgment message that shall contains the wfs:Status element with its value set to "cancelled". The HTTP status code in this case shall be set to "200 OK".

Note
 The "cancel" link may also be included in the response’s HTTP header using the Link field (see RFC 5988).
Note
 This document does not define a specific template, form or encoding of any link that appears in an acknowledgement message. Server implementations are free to encode the URI value of the href attribute of an atom:link element in whatever way they deem suitable.
Note
 When resolving links, this should be done with the same credentials as the original asynchronous request.
Figure 1. Sequence diagram for the Asynchronous Process Class
Examples

Example 1: Simple acknowledgement.

   <ows:Acknowledgement/>

Example 2: Simple acknowledgement with a hypermedia control to cancel the request.

   <ows:Acknowledgement>
      <atom:link rel="cancel" href="http://www.someserver.com/jobs/cancel/1013"/>
   </ows:Acknowledgement>

Asynchronous Polling class

Response semantics

For servers that implement the Asynchronous Polling conformance class, the ows:Acknowledgment message shall include an atom:link element, with rel="monitor", that may be periodically resolved to determine the execution status of an asynchronous request.

The response to resolving the rel="monitor" link shall be a ows:Acknowledgment message that shall contain the wfs:Status element indicating the execution status of the asynchronous request and may include a wfs:PercentCompleted element with a percentage value indicating how much of the request has been completed. The HTTP status code in this case shall be set to "200 OK".

Requesting the execution status of an asynchronous request after its processing has been completed — and the operation’s response is still available — shall result in an ows:Acknowledgement message that shall contain a wfs:Status element with its value set to "completed" and shall also include an atom:link element, with rel="http://www.opengis.net/def/rel/ogc/1.0/operationResponse", that provides a URI that may be used to retrieve the response.

Requesting the execution status of an asynchronous request after its processing has been completed — and the operation’s response is no longer available (e.g. is has expired) — shall result in an OGC exception message and the HTTP status code shall be set to "404 Not Found".

Note
 The rel "http://www.opengis.net/def/rel/ogc/1.0/operationResponse" is an extension relation type (see RFC 5988, Section 4.2) and shall, in due course, be defined with OGC Naming Authority.
Note
 The "http://www.opengis.net/def/rel/ogc/1.0/operationResponse", "monitor" and "cancel" links may also be included in the response’s HTTP header using the Link field (see RFC 5988).
Figure 2. Sequence diagram for the Asynchronous Polling Class

Examples

Example 1: The following example shows the response that a server that implements the Asynchronous Polling conformance class might initially generate in response to an asynchronously invoked operation. The acknowledgement message contains hypermedia controls to monitor the execution status of the request and to cancel the request. The execution status at this time is pending indicating that the request has been queued for execution.

<ows:Acknowledgement>
   <atom:link rel="monitor" href="http://www.someserver.com/jobs/1013"/>
   <atom:link rel="cancel" href="http://www.someserver.com/jobs/cancel/1013"/>
   <ows:Status>pending</ows:Status>
</ows:Acknowledgement>

Example 2: The following example shows a polling response some time after an operation was invoked asynchronously. The acknowledgement message contains hypermedia controls to monitor the execution status of the request and to cancel the request.

<ows:Acknowledgement>
   <atom:link rel="monitor" href="http://www.someserver.com/jobs/1013"/>
   <atom:link rel="cancel" href="http://www.someserver.com/jobs/cancel/1013"/>
   <ows:Status>executing</ows:Status>
   <ows:PercentCompleted>47</ows:PercentCompleted>
</ows:Acknowledgement>

Example 3: This following examples shows the polling response after request processing has been completed. Resolving the hypermedia control with rel="http://www.opengis.net/def/rel/ogc/1.0/operationResponse" will retrieve the request’s response if it is still available; if the response is not available (e.g. it has expired from the cache) resolving the control would result in an OGC exception message and a "404 Not Found".

<ows:Acknowledgement>
   <atom:link rel="http://www.opengis.net/def/rel/ogc/1.0/operationResponse"
              href="http://www.someserver.com/jobs/results/1013"/>
   <ows:Status>Completed</ows:Status>
</ows:Acknowledgement>

Notification message content

For servers that implement the Asynchronous Processing conformance class, an operation’s response shall be accessible via the notification message sent by the server using the specified response handler(s) (see [ResponseHandler]) to signal that request processing has been completed.

In general the content of a notification message shall either be the operation’s complete response, or a reference to it, or an exception message.

The specific content of a notification message is not defined in this document because it is dependent on the scheme(s) specified as the value of the ResponseHandler parameter (see [ResponseHandler]). For size-limited schemes, such as sms, a URL reference to the response would seem to be most appropriate since the entire response content is unlikely to fit into the message space. For other schemes, such as webhooks, the content of the notification message can be the complete response of the operation (e.g. the response to a GetFeature request). The following table contains informative recommendations for the content of notification messages based on the scheme being used:

Table 2. Recommended content for the notification message based on scheme
Notification scheme Recommended content (good response) Recommended content (exception)

mailto:

An email message containing a URL for retrieving the operation’s response.

An email message containing a narrative that describes the exception; an optional attachment with the server’s actual OGC exception message may also be included

sms:

A URL for retrieving the operation’s response; tiny URLs may be used if the retrieval URL is particularly long

A URL for retrieving the server’s OGC exception message; tiny URLs may be used if the retrieval URL is particularly long

http: (webhook)

The operation’s complete response

The complete OGC exception message

Capabilities document

Introduction

A server that implements the Asynchronous Processing conformance class shall advertise this fact in its capabilities document using the ImplementsAsyncProcessing service constraint.

A server that implements the Asynchronous Polling conformance class shall advertise this fact in its capabilities document using the ImplementsAsyncPolling service constraint.

A server that support asynchronous request processing shall, in its capabilities document, use the ResponseHandlerSchemes operation constraint to indicate which notification schemes it supports (e.g. mailto for email, http for webhooks, etc.) for each operation that may be executed asynchronously. The "poll" token shall be included in the list of response handler schemes if the service implements the Asynchronous Polling conformance class.

Examples

The following example shows the capabilities document for a server that implements the Asynchronous Processing conformance class.

   <?xml version="1.0" encoding="UTF-8"?>
   <WFS_Capabilities
      version="2.0.0"
      xmlns="http://www.opengis.net/wfs/2.0"
      xmlns:xlink="http://www.w3.org/1999/xlink"
      xmlns:ows="http://www.opengis.net/ows/1.1"
      xmlns:cw="http://schemas.cubewerx.com/namespaces/null"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.opengis.net/wfs/2.0 http://schemas.cubewerx.com/schemas/wfs/2.0/wfs.xsd http://www.opengis.net/ows/1.1 http://schemas.cubewerx.com/schemas/ows/1.1.0/owsAll.xsd">
      <ows:ServiceIdentification xmlns:ows="http://www.opengis.net/ows/1.1">
         <ows:Title>CubeSERV WFS - New CubeSTOR (mysql)</ows:Title>
         <ows:Abstract xml:lang="en">WFS-compliant web feature server by CubeWerx Inc.</ows:Abstract>
         <ows:ServiceType>WFS</ows:ServiceType>
         <ows:ServiceTypeVersion>2.5.0</ows:ServiceTypeVersion>
         <ows:ServiceTypeVersion>2.0.2</ows:ServiceTypeVersion>
         <ows:ServiceTypeVersion>2.0.0</ows:ServiceTypeVersion>
         <ows:ServiceTypeVersion>1.1.1</ows:ServiceTypeVersion>
         <ows:ServiceTypeVersion>1.1.0</ows:ServiceTypeVersion>
         <ows:ServiceTypeVersion>1.0.0</ows:ServiceTypeVersion>
      </ows:ServiceIdentification>
      <ows:ServiceProvider xmlns:ows="http://www.opengis.net/ows/1.1"
         xmlns:xlink="http://www.w3.org/1999/xlink">
         <ows:ProviderName>CubeWerx Inc.</ows:ProviderName>
         <ows:ProviderSite xlink:href="http://www.cubewerx.com/"/>
         <ows:ServiceContact>
            <ows:IndividualName>Mike Galluchon</ows:IndividualName>
            <ows:PositionName>Technical Support</ows:PositionName>
            <ows:ContactInfo>
               <ows:Phone>
                  <ows:Voice>(819) 771-8303</ows:Voice>
                  <ows:Facsimile>(819) 771-8388</ows:Facsimile>
               </ows:Phone>
               <ows:Address>
                  <ows:DeliveryPoint>815 boulevard de la Carrière, bureau 202</ows:DeliveryPoint>
                  <ows:City>Gatineau</ows:City>
                  <ows:AdministrativeArea>Québec</ows:AdministrativeArea>
                  <ows:PostalCode>J8Y 6T4</ows:PostalCode>
                  <ows:Country>Canada</ows:Country>
                  <ows:ElectronicMailAddress>support@cubewerx.com</ows:ElectronicMailAddress>
               </ows:Address>
            </ows:ContactInfo>
         </ows:ServiceContact>
      </ows:ServiceProvider>
      <ows:OperationsMetadata>
         <ows:Operation name="GetCapabilities">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="AcceptVersions">
               <ows:AllowedValues>
                  <ows:Value>2.5.0</ows:Value>
                  <ows:Value>2.0.2</ows:Value>
                  <ows:Value>2.0.0</ows:Value>
                  <ows:Value>1.1.1</ows:Value>
                  <ows:Value>1.1.0</ows:Value>
                  <ows:Value>1.0.0</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="AcceptFormats">
               <ows:AllowedValues>
                  <ows:Value>text/xml</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="Sections">
               <ows:AllowedValues>
                  <ows:Value>ServiceIdentification</ows:Value>
                  <ows:Value>ServiceProvider</ows:Value>
                  <ows:Value>OperationsMetadata</ows:Value>
                  <ows:Value>FeatureTypeList</ows:Value>
                  <ows:Value>SupportsGMLObjectTypeList</ows:Value>
                  <ows:Value>Filter_Capabilities</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
         </ows:Operation>
         <ows:Operation name="GetDescription">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="outputFormat">
               <ows:AllowedValues>
                  <ows:Value>text/html</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
         </ows:Operation>
         <ows:Operation name="DescribeFeatureType">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="version">
               <ows:AllowedValues>
                  <ows:Value>2.5.0</ows:Value>
                  <ows:Value>2.0.2</ows:Value>
                  <ows:Value>2.0.0</ows:Value>
                  <ows:Value>1.1.1</ows:Value>
                  <ows:Value>1.1.0</ows:Value>
                  <ows:Value>1.0.0</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="TypeName">
               <ows:AllowedValues>
                  <ows:Value>cw:builtupa_1m</ows:Value>
                  <ows:Value>cw:coastl_1m</ows:Value>
                  <ows:Value>cw:depthl_1m</ows:Value>
                  <ows:Value>cw:polbndl_1m</ows:Value>
                  <ows:Value>cw:soundings</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="outputFormat">
               <ows:AllowedValues>
                  <ows:Value>text/xml; subtype="bxfs/0.0.3"</ows:Value>
                  <!-- ... -->
                  <ows:Value>XMLSCHEMA</ows:Value>
                  <!-- ... -->
                  <ows:Value>application/gml+xml; version=3.2</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
         </ows:Operation>
         <ows:Operation name="ListStoredQueries">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="version">
               <ows:AllowedValues>
                  <ows:Value>2.5.0</ows:Value>
                  <ows:Value>2.0.2</ows:Value>
                  <ows:Value>2.0.0</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
         </ows:Operation>
         <ows:Operation name="DescribeStoredQueries">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="version">
               <ows:AllowedValues>
                  <ows:Value>2.5.0</ows:Value>
                  <ows:Value>2.0.2</ows:Value>
                  <ows:Value>2.0.0</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
         </ows:Operation>
         <ows:Operation name="GetPropertyValue">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="version">
               <ows:AllowedValues>
                  <ows:Value>2.5.0</ows:Value>
                  <ows:Value>2.0.2</ows:Value>
                  <ows:Value>2.0.0</ows:Value>
                  <ows:Value>1.1.1</ows:Value>
                  <ows:Value>1.1.0</ows:Value>
                  <ows:Value>1.0.0</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="outputFormat">
               <ows:AllowedValues>
                  <ows:Value>text/xml; subtype="bxfs/0.0.3"</ows:Value>
                  <!-- ... -->
                  <ows:Value>application/gml+xml; version=3.2</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="resolve">
               <ows:AllowedValues>
                  <ows:Value>none</ows:Value>
                  <ows:Value>local</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="srsName">
               <ows:AllowedValues>
                  <ows:Value>urn:ogc:def:crs:EPSG::42110</ows:Value>
                  <!-- ... -->
                  <ows:Value>urn:ogc:def:crs:EPSG::102002</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
         </ows:Operation>
         <ows:Operation name="GetFeature">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="version">
               <ows:AllowedValues>
                  <ows:Value>2.5.0</ows:Value>
                  <ows:Value>2.0.2</ows:Value>
                  <ows:Value>2.0.0</ows:Value>
                  <ows:Value>1.1.1</ows:Value>
                  <ows:Value>1.1.0</ows:Value>
                  <ows:Value>1.0.0</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="outputFormat">
               <ows:AllowedValues>
                  <ows:Value>text/xml; subtype="bxfs/0.0.3"</ows:Value>
                  <!-- ... -->
                  <ows:Value>application/gml+xml; version=3.2</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="resolve">
               <ows:AllowedValues>
                  <ows:Value>none</ows:Value>
                  <ows:Value>local</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Parameter name="srsName">
               <ows:AllowedValues>
                  <ows:Value>urn:ogc:def:crs:EPSG::42110</ows:Value>
                  <!-- ... -->
                  <ows:Value>urn:ogc:def:crs:EPSG::102002</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
            <ows:Constraint name="ResponseHandlerSchemes">
               <ows:AllowedValues>
                  <ows:Value>mailto:</ows:Value>
               </ows:AllowedValues>
            </ows:Constraint>
         </ows:Operation>
         <ows:Operation name="GetAccessibility">
            <ows:DCP>
               <ows:HTTP>
                  <ows:Get
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql&amp;"/>
                  <ows:Post
                     xlink:href="http://tb12.cubewerx.com/cubewerx/cubeserv?datastore=foundation_mysql"/>
               </ows:HTTP>
            </ows:DCP>
            <ows:Parameter name="version">
               <ows:AllowedValues>
                  <ows:Value>2.5.0</ows:Value>
                  <ows:Value>2.0.2</ows:Value>
                  <ows:Value>2.0.0</ows:Value>
                  <ows:Value>1.1.1</ows:Value>
                  <ows:Value>1.1.0</ows:Value>
                  <ows:Value>1.0.0</ows:Value>
               </ows:AllowedValues>
            </ows:Parameter>
         </ows:Operation>
         <!-- ============================================================= -->
         <!--                     CONFORMANCE SECTION                       -->
         <!-- ============================================================= -->
         <ows:Constraint name="ImplementsBasicWFS">
            <ows:NoValues/>
            <ows:DefaultValue>TRUE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsTransactionalWFS">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsLockingWFS">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="KVPEncoding">
            <ows:NoValues/>
            <ows:DefaultValue>TRUE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="XMLEncoding">
            <ows:NoValues/>
            <ows:DefaultValue>TRUE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="SOAPEncoding">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsInheritance">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsRemoteResolve">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsResultPaging">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsStandardJoins">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsSpatialJoins">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsTemporalJoins">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsFeatureVersioning">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ManageStoredQueries">
            <ows:NoValues/>
            <ows:DefaultValue>FALSE</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="ImplementsAsyncProcessing">
            <ows:NoValues/>
            <ows:DefaultValue>TRUE</ows:DefaultValue>
         </ows:Constraint>
         <!-- ============================================================== -->
         <ows:Constraint name="CountDefault">
            <ows:NoValues/>
            <ows:DefaultValue>10</ows:DefaultValue>
         </ows:Constraint>
         <ows:Constraint name="QueryExpression">
            <ows:AllowedValues>
               <ows:Value>wfs:Query</ows:Value>
               <ows:Value>wfs:StoredQuery</ows:Value>
            </ows:AllowedValues>
         </ows:Constraint>
      </ows:OperationsMetadata>
      <FeatureTypeList>
         <FeatureType>
            <Name>cw:builtupa_1m</Name>
            <Title>builtupa_1m</Title>
            <DefaultCRS>urn:ogc:def:crs:EPSG::4269</DefaultCRS>
            <OtherCRS>urn:ogc:def:crs:EPSG::42110</OtherCRS>
            <!-- ... -->
            <OtherCRS>urn:ogc:def:crs:EPSG::102002</OtherCRS>
            <ows:WGS84BoundingBox>
               <ows:LowerCorner>-179.1296 -53.1674</ows:LowerCorner>
               <ows:UpperCorner>178.4432 70.9927</ows:UpperCorner>
            </ows:WGS84BoundingBox>
         </FeatureType>
         <FeatureType>
            <Name>cw:coastl_1m</Name>
            <Title>coastl_1m</Title>
            <DefaultCRS>urn:ogc:def:crs:EPSG::4326</DefaultCRS>
            <OtherCRS>urn:ogc:def:crs:EPSG::42110</OtherCRS>
            <!-- ... -->
            <OtherCRS>urn:ogc:def:crs:EPSG::102002</OtherCRS>
            <ows:WGS84BoundingBox>
               <ows:LowerCorner>-179.999 -85.5827</ows:LowerCorner>
               <ows:UpperCorner>179.9999 83.6274</ows:UpperCorner>
            </ows:WGS84BoundingBox>
         </FeatureType>
         <FeatureType>
            <Name>cw:depthl_1m</Name>
            <Title>depthl_1m</Title>
            <DefaultCRS>urn:ogc:def:crs:EPSG::4269</DefaultCRS>
            <OtherCRS>urn:ogc:def:crs:EPSG::42110</OtherCRS>
            <!-- ... -->
            <OtherCRS>urn:ogc:def:crs:EPSG::102002</OtherCRS>
            <ows:WGS84BoundingBox>
               <ows:LowerCorner>-179.9999 -78.1118</ows:LowerCorner>
               <ows:UpperCorner>179.9999 89.9186</ows:UpperCorner>
            </ows:WGS84BoundingBox>
         </FeatureType>
         <FeatureType>
            <Name>cw:polbndl_1m</Name>
            <Title>polbndl_1m</Title>
            <DefaultCRS>urn:ogc:def:crs:EPSG::4269</DefaultCRS>
            <OtherCRS>urn:ogc:def:crs:EPSG::42110</OtherCRS>
            <!-- ... -->
            <OtherCRS>urn:ogc:def:crs:EPSG::102002</OtherCRS>
            <ows:WGS84BoundingBox>
               <ows:LowerCorner>-179.9999 -89.9999</ows:LowerCorner>
               <ows:UpperCorner>179.9999 89.9979</ows:UpperCorner>
            </ows:WGS84BoundingBox>
         </FeatureType>
         <FeatureType>
            <Name>cw:soundings</Name>
            <Title>soundings</Title>
            <DefaultCRS>urn:ogc:def:crs:EPSG::4326</DefaultCRS>
            <OtherCRS>urn:ogc:def:crs:EPSG::3857</OtherCRS>
            <!-- ... -->
            <OtherCRS>urn:ogc:def:crs:EPSG::102002</OtherCRS>
            <ows:WGS84BoundingBox>
               <ows:LowerCorner>-138.6394 69.9340</ows:LowerCorner>
               <ows:UpperCorner>-138.6035 69.9549</ows:UpperCorner>
            </ows:WGS84BoundingBox>
         </FeatureType>
      </FeatureTypeList>
      <Filter_Capabilities xmlns="http://www.opengis.net/fes/2.0" ...>
         <!-- ... -->
      </Filter_Capabilities>
   </WFS_Capabilities>

Implementation for Test Bed 12

An implementation of the Asynchronous Processing class was deployed for test bed 12 at the following URL an Amazon’s Cloud:

http://tb12.cubewerx.com/a007/cubeserv?datastore=USGS&
   service=WFS&
   request=GetCapabilities

The implementation was unremarkable. As shown in the server’s capabilities document, this deployment only implements the "mailto:" response handler. Technology integration experiments were sucessfully performed with the ESRI (DG002) and GMU (A109) thread clients.