WCF Invoke method only if certain condition is met or waiting

Question

WCF Invoke method only if certain condition is met or waiting

I have a WCF service that implements ServiceContract

. For simplicity, it ServiceContract

is said to have only one method:

public interface ServiceContract
{
    String AddNewData(T arg1);
}

Here AddNewData

can add data to Database1

or Database2

depending on the value arg1

. At some point in time for a given value, arg1

let's say val1

we try to switch storage from Database1

to Database2

, and this process takes a long time (let's say it takes about a minute). During this period, all calls for arg1 == val1

must be suspended, but we must still execute AddNewData

for all other values arg1

, that is, we must not block the main thread.

I thought since it AddNewData

is the entry point for the call, I assume I want to be able to create Task

that does AddNewData

, but in case arg1 == val1

I am not executing the task, but keep it paused (in a non-running state) and when the transition from Database1

to occurs Database2

, I can run / start this suspended task. I was thinking in terms of a task as I don't want to block the main thread to execute AddNewData

for other values arg1

.

Now I'm not sure how I should decide if I want to start AddNewData

or not, even before entering a method for a given value arg1

. In my opinion, I cannot pause execution AddNewData

after entering the method as it blocks the main thread. I looked at IDispatchMessageInspector.AfterReceiveRequest but couldn't figure out how to use that.

Anyone with any suggestions as to how I should go about this. I'm new to WCF and multithreading, so please excuse me if I'm missing something right here.

+3

multithreading c # async-await wcf

unrealsoul007 May 17 '17 at 3:37 am

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1 answer

bradgonesurfing · Answer 1 · 2017-05-17T05:03:02+0000

Just use the async service contract

[ServiceContract]
public interface IServiceContract<T>
{
    [OperationContract]
    Task<string> AddNewData(T arg1);
}

then server side

const int val1 = 10;

public class HelloService<int> : IServiceContract<T>
{
    public async Task<string> AddNewData(int arg1)
    {
      if(arg1==val1){
         // Poll to see if the database is ready
         // or use some other method that returns a 
         // a task when it is ready
         while(!(await DataBaseReady())
             await Task.Delay(TimeSpan.FromSeconds(1));
       }
       return "Got it"
    }
}

The above was shamelessly ripped off

https://blogs.msdn.microsoft.com/endpoint/2010/11/12/simplified-asynchronous-programming-model-in-wcf-with-asyncawait/

and contains a complete example

WCF Invoke method only if certain condition is met or waiting

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