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Client interceptors

If we need to create a client we have a few methods that we can override:

  • BlockingUnaryCall: Intercepts a blocking invocation of an unary RPC.
  • AsyncUnaryCall: Intercepts an asynchronous invocation of an unary RPC.
  • AsyncClientStreamingCall: Intercepts an asynchronous invocation of a client-streaming RPC.
  • AsyncServerStreamingCall: Intercepts an asynchronous invocation of a server-streaming RPC.
  • AsyncDuplexStreamingCall: Intercepts an asynchronous invocation of a bidirectional-streaming RPC.

Configuring a client interceptor

To We can configure several interceptors, and these are executed in reverse order:

Interceptors order
var invoker = channel
    .Intercept(new ClientTokenInterceptor())
    .Intercept(new ClientMonitoringInterceptor())
    .Intercept(new ClientLoggerInterceptor());

When it comes to the actual execution order, that happens in reverse:

  1. ClientLoggerInterceptor - was last
  2. ClientMonitoringInterceptor
  3. ClientTokenInterceptor - was first

Configure interceptors on clients

client interceptors aren't configured with GrpcChannelOptions. Instead, client interceptors are configured using the Intercept extension method with a channel. This extension method is in the Grpc.Core.Interceptors namespace.

static async Task Main(string[] args)
{
   var channel = GrpcChannel.ForAddress("https://localhost:5001");
   var callInvoker = channel.Intercept(new LoggingInterceptor());
   var client = new Greeter.GreeterClient(callInvoker);

}