This package allows injecting custom headers into remoting messages (Actors and Reliable Services, V2 remoting only) at runtime. The headers are available client side to read. It also provides message interception using BeforeHandleRequestResponseAsync and AfterHandleRequestResponseAsync to act on remoting events.
Common used classes:
Nuget Package: ServiceFabric.Remoting.CustomHeaders
This repository includes a Service Fabric application for demonstration purposes. A Console Application is used to access the application and shows the usage of the package.
Custom headers can be used to pass data between the sender and the receiver like tracing information or security context data. Using the BeforeHandleRequestResponseAsync and AfterHandleRequestResponseAsync actions additional logging can be applied monitor the flow between remoting calls.
Create a listener that can handle the requests
protected override IEnumerable<ServiceInstanceListener> CreateServiceInstanceListeners()
{
yield return new ServiceInstanceListener(context =>
new FabricTransportServiceRemotingListener(context,
new ExtendedServiceRemotingMessageDispatcher(context, this)));
}Optionally the BeforeHandleRequestResponseAsync and AfterHandleRequestResponseAsync can be used to intercept the calls client side:
protected override IEnumerable<ServiceInstanceListener> CreateServiceInstanceListeners()
{
yield return new ServiceInstanceListener(context =>
new FabricTransportServiceRemotingListener(context,
new ExtendedServiceRemotingMessageDispatcher(context, this)
{
// Optional, log the call before being handled
BeforeHandleRequestResponseAsync = (message, method) =>
{
var sw = new Stopwatch();
sw.Start();
ServiceEventSource.Current.ServiceMessage(Context, $"BeforeHandleRequestResponseAsync {method}");
return Task.FromResult<object>(sw);
},
// Optional, log the call after being handled
AfterHandleRequestResponseAsync = (message, method, state) =>
{
var sw = (Stopwatch) state;
ServiceEventSource.Current.ServiceMessage(Context, $"AfterHandleRequestResponseAsync {method} took {sw.ElapsedMilliseconds}ms");
return Task.CompletedTask;
}
}));
}Register the actor using the ExtendedActorService service:
ActorRuntime.RegisterActorAsync<DemoActor> (
(context, actorType) =>
{
var service = new ExtendedActorService(context, actorType)
{
// Optional, allows call interception. Executed before the response is handled
BeforeHandleRequestResponseAsync = (message, method, id) =>
{
ActorEventSource.Current.Message($"BeforeHandleRequestResponseAsync {method} for actor {id.ToString()}");
return Task.CompletedTask;
},
// Optional, allows call interception. Executed after the response is handled
AfterHandleRequestResponseAsync = (message, method, id) =>
{
ActorEventSource.Current.Message($"AfterHandleRequestResponseAsync {method} for actor {id.ToString()}");
return Task.CompletedTask;
}
};
return service;
}).GetAwaiter().GetResult();On the sender side, use the ExtendedServiceProxy or ExtendedActorProxy class to create a proxy to the actor or service. The Create method accepts an instance of the CustomHeaders class:
var customHeaders = new CustomHeaders
{
{"Header1", DateTime.Now.ToString(CultureInfo.InvariantCulture)},
{"Header2", Guid.NewGuid().ToString()}
};
var serviceUri = new Uri("fabric:/ServiceFabric.Remoting.CustomHeaders.DemoApplication/DemoService");
var proxy = ExtendedServiceProxy.Create<IDemoService>(serviceUri, customHeaders);
var actorMessage = proxy.SayHello().GetAwaiter().GetResult();There is an overload of the Create method that accepts a Func<CustomHeaders>. This is useful in scenarios where the created proxy is reused. The func is invoked on every request made using the proxy:
var customHeaderProvider = new Func<CustomHeaders>(() => new CustomHeaders
{
{"Header1", DateTime.Now.ToString(CultureInfo.InvariantCulture)},
{"Header2", Guid.NewGuid().ToString()}
});
var serviceUri = new Uri("fabric:/ServiceFabric.Remoting.CustomHeaders.DemoApplication/DemoService");
var proxy = ExtendedServiceProxy.Create<IDemoService>(serviceUri, customHeaderProvider);The receiving service or actor can extract the values in the custom headers using the RemotingContext class:
public async Task<string> SayHello()
{
var remotingContext =
string.Join(", ", RemotingContext.Keys.Select(k => $"{k}: {RemotingContext.GetData(k)}"));
ServiceEventSource.Current.ServiceMessage(Context, $"SayHelloToActor got context: {remotingContext}");
return Task.FromResult($"Got the following message headers: {remotingContext}")
}Sample content of remotingContext:
Header1: 06/24/2018 08:30:18, Header2: 2c95548a-6efd-4855-82eb-29ea827be87b
In case the headers need to flow from one call to the other CustomHeaders.FromRemotingContext can be used as demonstrated:
public async Task<string> SayHelloToActor()
{
var remotingContext =
string.Join(", ", RemotingContext.Keys.Select(k => $"{k}: {RemotingContext.GetData(k)}"));
ServiceEventSource.Current.ServiceMessage(Context, $"SayHelloToActor got context: {remotingContext}");
var proxy = ExtendedActorProxy.Create<IDemoActor>(new ActorId(1), CustomHeaders.FromRemotingContext);
var response = await proxy.GetGreetingResponseAsync(CancellationToken.None);
return $"DemoService passed context '{remotingContext}' to actor and got as response: {response}";
}This removes the need to create a new CustomHeaders instance based on the current values in the RemotingContext.