<announcementEndpoint>

Artikel
02/24/2011

This configuration element defines a standard endpoint with a fixed announcement contract. A service can optionally announce its availability by sending an online and offline announcement message when it is opened or closed respectively. A Windows Communication Foundation (WCF) service specifies the announcement endpoints in the <serviceDiscovery> element and uses the AnnouncementClient to perform the announcements. A client wishing to listen for the announcement from other service is actually acting as a WCF service; thus you have to configure the announcement endpoints for that client in the <services> section.

Schema Hierarchy

<system.serviceModel>
<standardEndpoints>

Syntax

<system.serviceModel>
    <standardEndpoints>       <announcementEndpoint>           <standardEndpoint                  discoveryVersion=”WSDiscovery11/WSDiscoveryApril2005”                  maxAnnouncementDelay=”Timespan”                   name="String" />        </announcementEndpoint>            </standardEndpoints>
</system.serviceModel>

Attributes and Elements

The following sections describe attributes, child elements, and parent elements.

Attributes

Attribute	Description
discoveryVersion	A string that specifies one of the two versions of WS-Discovery protocol. Valid values are WSDiscovery11 and WSDiscoveryApril2005. This value is of type DiscoveryVersion.
maxAnnouncementDelay	A Timespan value that specifies the maximum value for the delay the Discovery protocol will wait before sending a Hello message. The messages will wait for a random time value between 0 and the value of this attribute before being sent. This attribute is used to set a small, random delay to prevent network storms when a network goes out and all services come back online at the same time.
name	A String that specifies the name of the configuration of the standard endpoint. The name is used in the endpointConfiguration attribute of the service endpoint to link a standard endpoint to its configuration.

Child Elements

None.

Parent Elements

Element	Description
<standardEndpoints>	A collection of standard endpoints that are pre-defined endpoints with one or more of their properties (address, binding, contract) fixed.

Example

The following example demonstrates a client listening for announcements messages over http and peernet.

<services>
  <service name="ServiceAnnouncementListener">
              <endpoint name="httpAnnouncementEndpoint"
                        kind="announcementEndpoint"
                        binding="basicHttpBinding"
                        address="announcements" />
              <endpoint name="peerNetAnnouncementEndpoint"
                        kind="announcementEndpoint"
                        binding="peerTcpBinding"
                        address="net.p2p://discoveryMesh/multicast"
                        bindingConfiguration="discoveryPeerTcpBindingConfig" />
  ...
  </service>
</services>

<standardEndpoints>
  <announcementEndpoint>
     <standardEndpoint name="httpAnnouncementEndpoint"                       
                       version="WSDiscoveryApril2005" />
     <standardEndpoint name="peerNetAnnouncementEndpoint"                       
                       version="WSDiscoveryApril2005" />
   </announcementEndpoint>
</standardEndpoints>

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