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C# gRPC with GrpcDotNetNamedPipes -- how to check if Client is connected to service?

I am using C# gRPC with GrpcDotNetNamedPipes to do interprocess communication on the same machine.
Currently, I am having a problem in that if my service is not set up, and I invoke a service request from my client side -- the client side just locks up waiting until the service is available.
I am unsure how to check if client has been connected to the service.
Example code below:
///Autogenerated gRPC code that contains COM API
public static partial class PluginCOM
{
public partial class PluginCOMClient : grpc::ClientBase<PluginCOMClient>
{
//Autogenerated code from protofile
//...
}
}
/// Client class that
public class PluginClient : PluginCOM.PluginCOMClient
{
public PluginClient() : base(new GrpcDotNetNamedPipes.NamedPipeChannel(".", "Service"))
{
}
public bool Test() => Test(new Empty()).Loaded;
}
public static class Tester
{
static void Test()
{
client = new PluginClient();
client.Test(); /// Deadlocks here and waits until service is available
}
}
Calling the Tester.Test() function dead locks when attempting to call client.Test().
I would like something like:
public static class Tester
{
static void Test()
{
client = new PluginClient();
if (/* code here to check if client is connected */)
{
client.Test();
}
}
}

I've had the same problem, but after looking at issues on official GitHub page finally found the solution:
https://github.com/cyanfish/grpc-dotnet-namedpipes/issues/17
By default connection timeout is set by Infinite, but you can set up timeout by yourself using NamedPipeChannelOptions:
public PluginClient() : base(new GrpcDotNetNamedPipes.NamedPipeChannel(".","Service",
new GrpcDotNetNamedPipes.NamedPipeChannelOptions { ConnectionTimeout = 350 }))
{
}

wcf callback reference

I have a desktop app with a duplex WCF service, but I have some troubles using the callback.
The service is started as following in main of program.cs:
ServiceHost svcHost = new ServiceHost(typeof(PeriodicService));
svcHost.Open();
Console.WriteLine("Available Endpoints :\n");
svcHost.Description.Endpoints.ToList().ForEach(endpoint => Console.WriteLine(endpoint.Address.ToString() + " -- " + endpoint.Name));
For the service I created a subscribe function where the callbackchannel is saved in a global variable, then the callback uses that global variable to talk back to the client (there will be only one client connecting).
IPeriodicCallback callbackClient;
public IPeriodicCallback Proxy
{
get
{
return this.callbackClient;
}
}
public void joinPeriodicService()
{
Console.WriteLine("Client subscribe");
this.callbackClient = OperationContext.Current.GetCallbackChannel<IPeriodicCallback>();
}
The thing I want to do now is call the callbackclient from an other class.
In the other class I created the service as:
private PeriodicService periodicService = new PeriodicService();
And I try to write data to it using:
if(this.periodicService.Proxy != null)
{
this.periodicService.Proxy.On1MinuteDataAvailable(tmpPeriod);
}
However the proxy stays null, I also tried to move the proxy part to the class but this also results in it staying null.
When the client connects I nicely get the message "Client Subscribe" but it seems there are two instances running of the periodicservice.
But my problem is I don't see an other way to access the periodicservice then creating it in my class, or is it also already created by the svcHost?
Can ayone point me in the right direction?

This repository shows the a duplex WCF imeplementation I made to answer a similar question a while ago, its a full working example with as little extra stuff as possible.
https://github.com/Aelphaeis/MyWcfDuplexPipeExample
Lets say we have a Service Contract like this :
[ServiceContract(CallbackContract = typeof(IMyServiceCallback),SessionMode = SessionMode.Required)]
public interface IMyService
{
[OperationContract(IsOneWay=true)]
void DoWork();
}
Note that I specified a CallbackContract.
If you want to make a duplex, you would want to perhaps make your Service Behavior implementation of the above contract like this :
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]
public class MyService : IMyService
{
public void DoWork()
{
Console.WriteLine("Hello World");
Callback.WorkComplete();
}
IMyServiceCallback Callback
{
get
{
return OperationContext.Current.GetCallbackChannel<IMyServiceCallback>();
}
}
}
The important thing here is the Callback. This is how your service would allow you to access specified to you by the Client.
You also need to define the callback interface, In my case its quite simple :
[ServiceContract]
public interface IMyServiceCallback
{
[OperationContract(IsOneWay = true)]
void WorkComplete();
}
Now I want to create a client to use this Duplex Service. The first thing I need to do is implement the IMyServiceCallback. I need to do this on the client. In this case the implementation is this:
class Callback : IMyServiceCallback
{
public void WorkComplete()
{
Console.WriteLine("Work Complete");
}
}
Now when I want to open my duplex connection with the services I would create a proxy class like this something like this:
public class MyServiceClient: IMyService, IDisposable
{
DuplexChannelFactory<IMyService> myServiceFactory { get; set; }
public MyServiceClient(IMyServiceCallback Callback)
{
InstanceContext site = new InstanceContext(Callback);
NetNamedPipeBinding binding = new NetNamedPipeBinding();
EndpointAddress endpointAddress = new EndpointAddress(Constants.myPipeService + #"/" + Constants.myPipeServiceName);
myServiceFactory = new DuplexChannelFactory<IMyService>(site, binding, endpointAddress);
}
public void DoWork()
{
myServiceFactory.CreateChannel().DoWork();
}
public void Dispose()
{
myServiceFactory.Close();
}
}
Notice that I specified an InstanceContext. That Instance Context will be an instance of the object I created that implements IMyServiceCallback.
That's all you need to do! Simple as that!
Update :
Callback objects are just like any other object. You can store them into a collection and iterate through them and based on some condition.
One way is to create a property in the IMyServiceCallback that can uniquely identify it. When a client connects to the service it can call a method which specifies a callback object which can then be cached or saved for later use. You can then iterate the callbacks and based on some condition you can call a method for a specific client.
This is certainly more complicated; however, it is certainly manageable. I will add an example in a bit.
Update 2
This is a working example of exactly what you want; however, its a lot more complicated. I'll try to explain as simply as I can : https://github.com/Aelphaeis/MyWcfDuplexPipeExample/tree/MultiClient
Here is a list of the changes:
I've modified the client proxy (and service) so that when initialized it calls the init Method
I've also modified the Service implementation so that now it is a single instance dealing with all requests (for convenience).
I added a new OperationContract in the Service interface called Msg
I've added a new Method in the IMyServiceCallback called RecieveMessage.
I've added a way to identify the client.
In the proxy class I have the following :
public MyServiceClient(IMyServiceCallback Callback)
{
InstanceContext site = new InstanceContext(Callback);
NetNamedPipeBinding binding = new NetNamedPipeBinding();
EndpointAddress endpointAddress = new EndpointAddress(Constants.myPipeService + #"/" + Constants.myPipeServiceName);
myServiceFactory = new DuplexChannelFactory<IMyService>(site, binding, endpointAddress);
Init();
}
public void Init()
{
myServiceFactory.CreateChannel().Init();
}
In my service I have the following :
public class MyService : IMyService
{
public List<IMyServiceCallback> Callbacks { get; private set; }
public MyService(){
Callbacks = new List<IMyServiceCallback>();
}
public void Init()
{
Callbacks.Add(Callback);
}
// and so on
My IMyServiceCallback has been redefined to :
[ServiceContract]
public interface IMyServiceCallback
{
[OperationContract]
int GetClientId();
[OperationContract(IsOneWay = true)]
void WorkComplete();
[OperationContract(IsOneWay = true)]
void RecieveMessage(String msg);
}
By specifying a number, you can contact the client that corresponds with that number. If two clients have the same Id, both clients will be contacted.

WCF client fields are losing values

I have a WCF service hosted on a console application the code is:
public interface ITestService
{
[OperationContract]
void SetField(string data);
[OperationContract]
string GetField();
}
public class TestService : ITestService
{
private string myData;
public string GetField()
{
retrun myData;
}
public void SetField(string data)
{
myData = data;
}
}
then I hosted it on a console application:
ServiceHost host = new ServiceHost(typeof(TestService));
host.Open();
Console.WriteLine("Test Service Host");
Console.WriteLine("Service Started!");
foreach (Uri address in host.BaseAddresses)
{
Console.WriteLine("Listening on " + address);
}
Console.WriteLine("Press any key to close the host...");
Console.ReadLine();
host.Close();
I started the console host then In an other console app I referenced the service and used it:
TestService client = new TestService();
client.SetField("test");
Console.WriteLine( client.GetField() );
this print nothing means the field is still null
What is wrong with this service?

What's wrong is that you're expecting that state will be persisted between calls - it is NOT. By default, WCF are absolutely stateless (and they should be! That's a good thing!)
If you need to persist information - store it into a persistent store (a.k.a a database).
Each WCF call will (by default) get a brand new, freshly created instance of TestService.
So your second call's instance knows nothing about the first instance (used by SetField) and therefore cannot return that value that you set in the first call.

Try this:
Use string as static.
public interface ITestService
{
[OperationContract]
void SetField(string data);
[OperationContract]
string GetField();
}
public class TestService : ITestService
{
private static string myData;
public string GetField()
{
retrun myData;
}
public void SetField(string data)
{
myData = data;
}
}

You should mark your service class with the attribute:
[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
public class TestService : ITestService
{
//...
}
This means that your service must have only one instance. And you must create the host like this:
var host = new ServiceHost(new TestService()); // or get a singleton..
host.Open();
Pay your attantion that you use an instance to create a service instead type. Then your code should work.

Cannot access ServiceHost methods

I have a Silverlight project that uses a WCF service that I created. My problem is that in my WCF service, I created a ServiceHost but VS2010 doesn't seem to recognize the instance of my object (underlines the svHost). Below is the code for my service.
using System;
using System.Collection.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
using System.ServiceModel.Activation;
namespace userIO.Web
{
[ServiceContract]
public class CoordsService
{
[OperationContract]
public double xDir();
[OperationContract]
public double yDir();
[OperationContract]
public String keyPressed();
public class Coords : CoordsService
{
public double xDir { get; set; }
public double yDir { get; set; }
public String keyPressed { get; set; }
}
ServiceHost svHost = new ServiceHost(typeof(Coords), new Uri("http://localhost:8080"));
BasicHttpBinding binding = new BasicHttpBinding();
svHost.AddServiceEndpoint(typeof(CoordsService), binding, "");
svHost.Open();
}
}

Your ServiceContract should decorate an interface (a contract). The ServiceHost should host an instance of this interface and be outside the same service that it's hosting. At least I've only seen it done in this way.
The basic structure is:
[ServiceContract]
public interface IService
{
[OperationContract]
void DoSomething(Data data);
}
[DataContract]
public class Data
{
[DataMember]
int Num {get;set;}
}
public class Service : IService
{
public void DoSomething(Data data)
{ // do something }
}
// run in any other kind of app, console, win service, winform/wpf
static void Main()
{
ServiceHost svHost = new ServiceHost(typeof(Service), new Uri("http://localhost:8080"));
BasicHttpBinding binding = new BasicHttpBinding();
svHost.AddServiceEndpoint(binding, "");
svHost.Open();
}
An even easier solution to get your service up and running in VS2010 is to just create the service in a new WCF Service template. Take out their demo code, put in your own code for the servicecontract interface and the implementation service, then choose debug -> run and VS2010 will host the service for you without having to create an external app to run the service. Will also let you send data to the service to test out the code and the return values of your wcf functions in their simple winforms app.

WCF invoke callback from static methods

I am very new to WCF and I am trying to learn but I think I am missing something significant here and I am aware of that so please be kind. I am working with a pre-existing console application that I have added a WCF host to, this is an oversimplified version of it but it should give you the jist of it
namespace mynamespace
{
public class MyConsoleApp
{
static void Main(string[] args)
{
CreateRemoteDebugHost();
StartLongRunningMethods();
}
public static void StartLongRunningMethods()
{
LongRunningMethod1();
LongRunningMethod2();
}
public static void LongRunningMethod1()
{}
public static void LongRunningMethod2()
{}
public void CreateRemoteDebugHost()
{
ServiceHost host = new ServiceHost(typeof(RemoteDebug), new Uri("net.pipe://localhost"));
host.AddServiceEndpoint(typeof(IRemoteDebug), new NetNamedPipeBinding(NetNamedPipeSecurityMode.None), "PipeRemoteDebug");
//Create mex
ServiceMetadataBehavior smb = new ServiceMetadataBehavior();
smb.HttpGetEnabled = true;
smb.HttpGetUrl = new Uri("http://localhost:8001/RemoteDebug");
host.Description.Behaviors.Add(smb);
host.Open();
}
}
[ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(IRemoteDebugCallback))]
public interface IRemoteDebug
{
[OperationContract]
string Message(string message);
}
public interface IRemoteDebugCallback
{
[OperationContract(IsOneWay = true)]
void OnMessage(string callbackValue);
}
public class RemoteDebug : IRemoteDebug
{
public string Message(string message)
{
IRemoteDebugCallback callback = OperationContext.Current.GetCallbackChannel<IRemoteDebugCallback>();
callback.OnMessage(message);
return message;
}
}
}
As you can probably tell I am trying to send debug or status messages back to a client(s) from inside of long running static methods. All the plumbing seems to be working correctly, the host comes up, I can add a service reference to my client application just fine but the trouble starts when try to invoke the WCF callback from the longrunningprocesses static methods. I can't seem to figure out how to do that properly.
What is also very confusing is that almost every example I have seen of WCF and callbacks assumes that everything you are doing is running from within the context of the WCF host itself, obviously in my example this is not the case. I know I'm probably going aobut this all wrong so could someone please set me straight on this? Any help is greatly appreciated.
TIA!

There is client (not to be confused with the client program) created as well through app.config or manually (e.g. public class MyClient: ClientBase<IRemoteDebug> or public class MyClient: DuplexClientBase<IRemoteDebug>, IRemoteDebug). This should send messages to the client programs. Example using DuplexClient above from some code I had:
[CallbackBehaviorAttribute(UseSynchronizationContext = true)]
public class SubCallback : IRemoteDebug
{
public void Event(SomeClass evt)
{
// some handling code using:
//public delegate void EventCallbackHandler(SomeClass evt);
}
}
InstanceContext ctx = new InstanceContext(new SubCallback ());
MyClient _client = new MyClient(
ctx,
new NetNamedPipeBinding(NetNamedPipeSecurityMode.None),
new EndpointAddress("net.pipe://localhost/ServiceEndpointName"));
Also, you may want to pass some options to your service, such as:
[ServiceBehavior(
InstanceContextMode = InstanceContextMode.Single,
ConcurrencyMode = ConcurrencyMode.Single)]
public class RemoteDebug : IRemoteDebug
{}
It could be many things causing your particular issue, but this solved problems for me.