Dotmad.net

I recently needed to build a WCF UDP application as a proof of concept.

Sadly UDP is not among the channels bundled with the WCF, so I needed to put up something myself:

• Downloaded the WCF technology samples, containing a UDP transport demo (there used to be a sample at the netfx3 site, but it’s long-gone)
• Copied the UDP transport sample project (from the folder \Extensibility\Transport\Udp\Cs\UdpTransport) into my solution
• Added the extensions section to the config file to add the UDP support (config file coming up soon)
• Added multicast=”true” switch to the binding section
• The address prefix is hardcoded in the UdpChannelHelpers.cs file, so if you like something other than “soap.udp” you need to edit the “Scheme” constant.
• Since UDP is limited by a 64kb packet size, you may also want to use the GZipEncoder (found in \Extensibility\MessageEncoder\Compression\CS\GZipEncoder)

You need to remember that since this is multicast, the client is the one doing the transmitting while the service is a only a passive listener.

Client configuration:

<configuration>    <system.serviceModel>

      <extensions>        <bindingElementExtensions>          <add name="udpTransport" type="Microsoft.ServiceModel.Samples.UdpTransportElement, UdpTransport" />        </bindingElementExtensions>        <bindingExtensions>          <add name="sampleProfileUdpBinding" type="Microsoft.ServiceModel.Samples.SampleProfileUdpBindingCollectionElement, UdpTransport" />        </bindingExtensions>      </extensions>

      <client>        <endpoint address="net.udp://225.225.0.1:2222/Observer/"          binding="customBinding"          bindingConfiguration="DatagramServer" contract="DataContracts.IObserver"          name="ClientService" />      </client>

      <bindings>        <customBinding>          <binding name="DatagramServer">            <binaryMessageEncoding></binaryMessageEncoding>            <udpTransport multicast="true" />          </binding>        </customBinding>      </bindings>

    </system.serviceModel></configuration>

Service configuration:

<configuration>    <system.serviceModel>

      <extensions>        <bindingElementExtensions>          <add name="udpTransport" type="Microsoft.ServiceModel.Samples.UdpTransportElement, UdpTransport" />        </bindingElementExtensions>        <bindingExtensions>          <add name="sampleProfileUdpBinding" type="Microsoft.ServiceModel.Samples.SampleProfileUdpBindingCollectionElement, UdpTransport" />        </bindingExtensions>      </extensions>

      <services>            <service name="ObserverService.Observer">              <endpoint address="net.udp://225.225.0.1:2222/Observer/"                   binding="customBinding"                  bindingConfiguration="DatagramServer"                  contract="DataContracts.IObserver" />            </service>       </services>      <bindings>        <customBinding>          <binding name="DatagramServer">            <binaryMessageEncoding></binaryMessageEncoding>            <udpTransport multicast="true" />          </binding>        </customBinding>      </bindings>    </system.serviceModel>

</configuration>