Monotouch/WCF: How to consume the wcf service without svcutil

Question

Becuase monotouch compile to native code, so it has some limitation such as dynamic invoke is not allowed.

But I have a lot class in .net, that I use the ChannelFactory dynamic to invoke the wcf service: new ChannelFactory(myBinding, myEndpoint); Now in monotouch I should use the slsvcutil to generate the wcf proxy class, but the slsvcutil generate a lot of Unnecessary extra code (huge), and Makes consumers difficult to unit test, due to high coupling with the WCF infrastructure through the ClientBase class.

Is there a better solution except the ChannelFactory? I would rather write the code manually, have more control over how services are invoked such as the ChannelFactory.

==========

        ChannelFactory<IMyContract> factory = new ChannelFactory<IMyContract>(binding, endpointAddress);
        return factory.CreateChannel();

//==> It throw exception: MonoTouch does not support dynamic proxy code generation. Override this method or its caller to return specific client proxy instance

This also affects ClientBase<T> clients of WCF services. "MonoTouch does not support dynamic proxy code generation. Override this method or its caller to return specific client proxy instance". Trying to override the ChannelBase<T> as described @Tyson's answer does not work as the Invoke() method is only available for some target frameworks and is not part of netstandard2.0. We are left with a Begin/EndInvoke() that only throws Null ref ex. — StingyJack
Hi @StingyJack ! Yes! That is what happends to me, I have no Invoke available. So, what I have to do to connect WCF from iOS in Xamarin.Forms with .Net standard 2.0? — Ignacio
@Ignacio - I don't know yet. You should be able to use the set of BeginInvoke() and EndInvoke() inside the ChannelBase<T> and accomplish the same as the Invoke(), but its not working for me. I get null reference exceptions, I think are because the runtime is not able to match the Begin invocation to the correct End invocation. I tried a few different ways, and still no joy =< — StingyJack
@StingyJack I could make it work one minute ago! What I have done is regenerated the Connected Service Reference file with svcutil in the version of Visual Studio 15.8.1 with this command svcutil /async /tcv:Version35 https://... then using this on the sync methods: var iar = BeginInvoke("YourMethod", _args, null, null); return (string)EndInvoke("YourMethod", Array.Empty<object>(), iar);. — Ignacio
Thanks for the tip @Ignacio, I don't actually have any service references or connected services (have long used IChannelFactory to enable sharing of types rather than generate new types at every service consumer), but if that works I'm sure I can find what is different between my attempt and the generated code. — StingyJack

Tyson Tyson · Accepted Answer · 2012-04-07T16:56:01

ChannelFactory<T> has a virtual method CreateChannel(). If this is not overridden, it uses dynamic code generation, which fails on MonoTouch.

The solution is to override it and provide your own compile-time implementation.

Below is an old service implementation of mine that at least used to work on MonoTouch. I split it up into 2 partial classes - the first one being linked in all builds, the 2nd only in the iOS builds (allowing the dynamic generation mechanism to still work on windows).
I've stripped it down to only contain 1 service call.

TransactionService.cs:

public partial class TransactionService : ClientBase<IConsumerService>, IConsumerService
{

    public TransactionService()
    {
    }

    public TransactionService(string endpointConfigurationName) : 
        base(endpointConfigurationName)
    {
    }

    public TransactionService(string endpointConfigurationName, string remoteAddress) : 
        base(endpointConfigurationName, remoteAddress)
    {
    }

    public TransactionService(string endpointConfigurationName, EndpointAddress remoteAddress) : 
        base(endpointConfigurationName, remoteAddress)
    {
    }

    public TransactionService(Binding binding, EndpointAddress remoteAddress) : 
        base(binding, remoteAddress)
    {
    }

    public AccountBalanceResponse GetAccountBalance( AccountBalanceQuery query )
    {
        return Channel.GetAccountBalance( query );
    }
}

TransactionService.iOS.cs: ConsumerServiceClientChannel which executes the calls via reflection)

public partial class TransactionService
{
    protected override IConsumerService CreateChannel()
    {
        return new ConsumerServiceClientChannel(this);
    }

    private class ConsumerServiceClientChannel : ChannelBase<IConsumerService>, IConsumerService
    {

        public ConsumerServiceClientChannel(System.ServiceModel.ClientBase<IConsumerService> client) :
            base(client)
        {
        }

        // Sync version
        public AccountBalanceResponse GetAccountBalance(AccountBalanceQuery query)
        {
            object[] _args = new object[1];
            _args[0] = query;
            return (AccountBalanceResponse)base.Invoke("GetAccountBalance", _args);
        }

        // Async version
        public IAsyncResult BeginGetAccountBalance(AccountBalanceQuery query, AsyncCallback callback, object asyncState )
        {
            object[] _args = new object[1];
            _args[0] = query;
            return (IAsyncResult)base.BeginInvoke("GetAccountBalance", _args, callback, asyncState );
        }


        public AccountBalanceResponse EndGetAccountBalance(IAsyncResult asyncResult)
        {
            object[] _args = new object[0];
            return (AccountBalanceResponse)base.EndInvoke("GetAccountBalance", _args, asyncResult);
        }

    }
}

EDIT: I just tested this with the latest MT (5.2) - it no longer needs all that extra boiler plate I had in there before, just the CreateChannel() override. I've cleaned up the sample code to match.

EDIT2: I added an async method implementation.

Monotouch/WCF: How to consume the wcf service without svcutil

2 Answers