io.grpc.ClientInterceptor Maven / Gradle / Ivy
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package io.grpc;
import javax.annotation.concurrent.ThreadSafe;
/**
* Interface for intercepting outgoing calls before they are dispatched by a {@link Channel}.
*
* Implementers use this mechanism to add cross-cutting behavior to {@link Channel} and
* stub implementations. Common examples of such behavior include:
*
* - Adding credentials to header metadata
* - Logging and monitoring call behavior
* - Request and response rewriting
*
*/
@ThreadSafe
public interface ClientInterceptor {
/**
* Intercept {@link ClientCall} creation by the {@code next} {@link Channel}.
*
* Many variations of interception are possible. Complex implementations may return a wrapper
* around the result of {@code next.newCall()}, whereas a simpler implementation may just modify
* the header metadata prior to returning the result of {@code next.newCall()}.
*
* @param method the remote method to be called.
* @param callOptions the runtime options to be applied to this call.
* @param next the channel which is being intercepted.
* @return the call object for the remote operation, never {@code null}.
*/
ClientCall interceptCall(
MethodDescriptor method,
CallOptions callOptions,
Channel next);
}