Package io.grpc

Interface ServerInterceptor

public interface ServerInterceptor

Interface for intercepting incoming calls before they are dispatched by ServerCallHandler.

Implementers use this mechanism to add cross-cutting behavior to server-side calls. Common example of such behavior include:

• Enforcing valid authentication credentials
• Logging and monitoring call behavior
• Delegating calls to other servers

From gRPC's perspective, interceptors don't generally exist and are more of a convenience. Convenience APIs will use ServerInterceptors to convert the interceptor into a ServerCallHandler. Thus interceptors are an extension of the application and run on the same threads and receive callbacks using the same executor.

The interceptor may be called for multiple calls by one or more threads without completing the previous ones first. Refer to the ServerCall.Listener docs for more details regarding thread safety of the returned listener.

This interface is thread-safe.

Method Summary

Modifier and Type	Method	Description
<ReqT,RespT> ServerCall.Listener<ReqT>	interceptCall(ServerCall<ReqT,RespT> call, Metadata headers, ServerCallHandler<ReqT,RespT> next)	Intercept ServerCall dispatch by the next ServerCallHandler.

Method Detail

interceptCall

<ReqT,RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT,RespT> call,
                                                           Metadata headers,
                                                           ServerCallHandler<ReqT,RespT> next)

Intercept ServerCall dispatch by the next ServerCallHandler. General semantics of ServerCallHandler.startCall(io.grpc.ServerCall<RequestT, ResponseT>, io.grpc.Metadata) apply and the returned ServerCall.Listener must not be null.

If the implementation throws an exception, call will be closed with an error. Implementations must not throw an exception if they started processing that may use call on another thread.

Parameters:

call - object to receive response messages

headers - which can contain extra call metadata from ClientCall.start(io.grpc.ClientCall.Listener<RespT>, io.grpc.Metadata), e.g. authentication credentials.

next - next processor in the interceptor chain

Returns:

listener for processing incoming messages for call, never null.