C# 4 and .NET 4

service implementation ❘ 1297
code snippet StateServiceSample/app.config
If you start the service host with the defined configuration, an exception of type InvalidOperationException
is thrown. The error message with the exception gives this error message: “Contract requires Session, but
Binding ‘BasicHttpBinding’ doesn’t support it or isn’t configured properly to support it.”
Not all bindings support all services. Because the service contract requires a session with the attribute
[ServiceContract(SessionMode=SessionMode.Required)], the host fails because the configured
binding does not support sessions.
As soon as you change the configuration to a binding that supports sessions (for example, the
wsHttpBinding), the server starts successfully:
code snippet StateServiceSample/app.config
Creating a Client Programmatically
Now a client application can be created. In the previous example, the client application was created by
adding a service reference. Instead of adding a service reference, you can directly access the assembly
containing the contract interface and use the ChannelFactory class to instantiate the channel
to connect to the service.
The constructor of the class ChannelFactory accepts the binding configuration and endpoint
address. The binding must be compatible with the binding defined with the service host, and the address
defined with the EndpointAddress class references the URI of the running service.
The CreateChannel() method creates a channel to connect to the service. Then, you can invoke methods
of the service, and you can see that the service instance holds state until the Close() method that has the
IsTerminating operation behavior assigned is invoked:
using System;
using System.ServiceModel;
namespace Wrox.ProCSharp.WCF
{
class Program
{
static void Main()
{
var binding = new WSHttpBinding();
var address = new EndpointAddress("http://localhost:8731/" +
"Design_Time_Addresses/StateServiceSample/Service1/");
var factory = new ChannelFactory(binding, address);
IStateService channel = factory.CreateChannel();
channel.Init(1);
Console.WriteLine(channel.GetState());
channel.SetState(2);
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