io.grpc

Interface ClientInterceptor

@ThreadSafe
public interface ClientInterceptor

Interface for intercepting outgoing calls before they are dispatched by a Channel.

Implementers use this mechanism to add cross-cutting behavior to Channel and stub implementations. Common examples of such behavior include:

• Logging and monitoring call behavior
• Adding metadata for proxies to observe
• Request and response rewriting

Providing authentication credentials is better served by CallCredentials. But a ClientInterceptor could set the CallCredentials within the CallOptions.

Method Summary

Modifier and Type	Method and Description
<ReqT,RespT> ClientCall<ReqT,RespT>	interceptCall(MethodDescriptor<ReqT,RespT> method, CallOptions callOptions, Channel next) Intercept ClientCall creation by the next Channel.

Method Detail

interceptCall

<ReqT,RespT> ClientCall<ReqT,RespT> interceptCall(MethodDescriptor<ReqT,RespT> method,
                                                  CallOptions callOptions,
                                                  Channel next)

Intercept ClientCall creation by the next Channel.

Many variations of interception are possible. Complex implementations may return a wrapper around the result of next.newCall(), whereas a simpler implementation may just modify the header metadata prior to returning the result of next.newCall().

next.newCall() must not be called under a different Context other than the current Context. The outcome of such usage is undefined and may cause memory leak due to unbounded chain of Contexts.

Parameters:

method - the remote method to be called.

callOptions - the runtime options to be applied to this call.

next - the channel which is being intercepted.

Returns:

the call object for the remote operation, never null.