C# 4 and .NET 4

Building P2P applications ❘ 1351
}
}
break;
The endpoint URL is validated, and then the WCF service is registered and started:
// Check for null address
if (serviceUrl == null)
{
// Display error and shutdown
MessageBox.Show(this, "Unable to determine WCF endpoint.",
"Networking Error", MessageBoxButton.OK, MessageBoxImage.Stop);
Application.Current.Shutdown();
}
// Register and start WCF service.
localService = new P2PService(this, username);
host = new ServiceHost(localService, new Uri(serviceUrl));
NetTcpBinding binding = new NetTcpBinding();
binding.Security.Mode = SecurityMode.None;
host.AddServiceEndpoint(typeof(IP2PService), binding, serviceUrl);
try
{
host.Open();
}
catch (AddressAlreadyInUseException)
{
// Display error and shutdown
MessageBox.Show(this, "Cannot start listening, port in use.",
"WCF Error", MessageBoxButton.OK, MessageBoxImage.Stop);
Application.Current.Shutdown();
}
A singleton instance of the service class is used to enable easy communication between the host app and the
service (for sending and receiving messages). Also, note that security is disabled in the binding configuration
for simplicity.
Next, the System.Net.PeerToPeer namespace classes are used to register a peer name:
}
// Create peer name
peerName = new PeerName("P2P Sample", PeerNameType.Unsecured);
// Prepare peer name registration in link local clouds
peerNameRegistration = new PeerNameRegistration(peerName, int.Parse(port));
peerNameRegistration.Cloud = Cloud.AllLinkLocal;
// Start registration
peerNameRegistration.Start();
When the Refresh button is clicked the RefreshButton_Click() event handler uses PeerNameResolver
.ResolveAsync() to get peers asynchronously:
private void RefreshButton_Click(object sender, RoutedEventArgs e)
{
// Create resolver and add event handlers
PeerNameResolver resolver = new PeerNameResolver();
resolver.ResolveProgressChanged +=
new EventHandler(
resolver_ResolveProgressChanged);
resolver.ResolveCompleted +=
new EventHandler(
resolver_ResolveCompleted);
// Prepare for new peers
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