Question

I am a beginner to WCF. I am trying to make a device driver network accessible.
Code I have right now, simplified:

A.cs

public class A {
    public int source;
}

Driver.cs

public class Driver {
    // some fields here
    A a;

    // singleton class
    private Driver() {
        a = null;
        // some more code
    }

    // static methods
    public static Driver OpenDevice(int n) {
        Driver d = null;
        // some code
        i = GetBoardNumber();
        // some native code to actually open driver ONLY IF it wasn't already opened!
        d = new Driver();
        return d;
    }
    public static int GetDeviceNumber() {
        // some native code get device number
        return someInt;
    }

    // some non static methods which use native code
    // example:
    public int ResetDevice(){
        // some code
        // call native i_ResetDevice() method
        return code;
    }
}

DllImport.cs

public class DllImport {
    // some code to import method definitions from dll
    // example:
    [DllImport("MyDeviceDriverProvidedForWindows.dll")]
        public static extern int i_ResetDevice();
    // some more code
}

This Driver works very well for me. In the examples that control the device, I simply add reference to this Driver and control the Device using driver’s methods.

MyService d = Driver.OpenDevice(0);
d.ControlDevice();

My job is to make this Driver remotely accessible, and I chose to do it using WCF.

Since, I already had implementation, I extracted an interface and turned it into a valid WCF service contract by putting OperationContracts and proper places. This extracted interface did not have the OpenDevice and GetDeviceNumber methods because, they were static.

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The problems I am having are:

1) Opening WSDL file tells me to use some code like this in client:

MyServiceClient client = new MyServiceClient();
// access client operations
// close client
client.Close();

what is this MyServiceRefernce.MyServiceClient(MyServiceReference is name of the service reference I added to the client)? Why is it calling the private constructor of MyService class on server?

2) How can I do something like this in the client?

MyServiceReference.Driver d = MyServiceRefernce.Driver.OpenDevice(0);

I have read about InstanceContextMode but not really sure how to use it my situation.

I understand it is hard to understand what I am asking exactly, but it really is hard for me to explain too! I wish I had someone with me who knew WCF well.

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The actual driver source I am using is in Assembly folder in this file.

Answer 1

You not make a WCF service use a single instance by making the service class a singleton. You need to configure the WCF service so it uses only a single instance. Also you can create a session-based WCF service. See this, for example.