C# WCF closing channels and using functions Func<T>

Question

This is the point, I have a WCF service, it is working now. So I begin to work on the client side. And when the application was running, then an exception showed up: timeout. So I began to read, there are many examples about how to keep the connection alive, but, also I found that the best way, is create channel, use it, and dispose it. And honestly, I liked that. So, now reading about the best way to close the channel, there are two links that could be useful to anybody who needs them:

1. Clean up clients, the right way

2. Using Func

In the first link, this is the example:

    IIdentityService _identitySvc;
...
if (_identitySvc != null)
 {
     ((IClientChannel)_identitySvc).Close();
     ((IDisposable)_identitySvc).Dispose();
     _identitySvc = null;
 }

So, if the channel is not null, then is closed, disposed, and assign null. But I have a little question. In this example the channel has a .Close() method, but, in my case, intellisense is not showing a Close() method. It only exists in the factory object. So I believe I have to write it. But, in the interface that has the contracts or the class that implemets it??. And, what should be doing this method??.

Now, the next link, this has something I haven't try before. Func<T>. And after reading the goal, it's quite interesting. It creates a funcion that with lambdas creates the channel, uses it, closes it, and dipose it. This example implements that function like a Using() statement. It's really good, and a excellent improvement. But, I need a little help, to be honest, I can't understand the function, so, a little explanatino from an expert will be very useful. This is the function:

TReturn UseService<TChannel, TReturn>(Func<TChannel, TReturn> code)
{
    var chanFactory = GetCachedFactory<TChannel>();
    TChannel channel = chanFactory.CreateChannel();
    bool error = true; 
    try {
        TReturn result = code(channel); 
        ((IClientChannel)channel).Close();
        error = false; 
        return result; 
    }
    finally {
        if (error) {
            ((IClientChannel)channel).Abort();
        }
    }
}

And this is how is being used:

int a = 1; 
int b = 2; 
int sum = UseService((ICalculator calc) => calc.Add(a, b)); 
Console.WriteLine(sum);

Yep, I think is really, really good, I'd like to understand it to use it in the project I have.

And, like always, I hope this could be helpful to a lot of people.

Answer 1

the UseService method accepts a delegate, which uses the channel to send request. The delegate has a parameter and a return value. You can put the call to WCF service in the delegate.

And in the UseService, it creates the channel and pass the channel to the delegate, which should be provided by you. After finishing the call, it closes the channel.