Variable<string> message = new Variable<string>("message", "client");
Variable<string> result = new Variable<string> { Name = "result" };

Endpoint endpoint = new Endpoint
{
    AddressUri = new Uri(Common.Constants.ServiceBaseAddress),
    Binding = new BasicHttpBinding(),
};

Send requestEcho = new Send
{
    ServiceContractName = XName.Get("Echo", "http://tempuri.org/"),
    Endpoint = endpoint,
    OperationName = "Echo",
    Content = new SendParametersContent
    {
        Parameters = 
            { 
                { "message", new InArgument<string>(message) }
            }
    }
};
workflow = new CorrelationScope
{
    Body = new Sequence
    {
        Variables = { message, result },
        Activities =
        {
            new WriteLine {
                Text = new InArgument<string>("Hello")
            },
            requestEcho,
            new ReceiveReply
            {
                Request = requestEcho,
                Content = new ReceiveParametersContent                            
                {
                    Parameters = 
                    {
                        { "echo", new OutArgument<string>(result) }
                    }
                }
            },                        
            new WriteLine {
                Text = new InArgument<string>(result)
            }
        }
    }
};