Channel.java

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package io.grpc;

import javax.annotation.concurrent.ThreadSafe;

/**
 * A Channel provides an abstraction over the transport layer that is designed to be consumed
 * by stub implementations. Channel and its associated types {@link ClientCall} and
 * {@link ClientCall.Listener} exchange parsed request and response objects whereas the
 * transport layer only works with serialized data.
 *
 * <p>Applications can add common cross-cutting behaviors to stubs by decorating Channel
 * implementations using {@link ClientInterceptor}. It is expected that most application
 * code will not use this class directly but rather work with stubs that have been bound to a
 * Channel that was decorated during application initialization,
 */
@ThreadSafe
public abstract class Channel {
  /**
   * Create a {@link ClientCall} to the remote operation specified by the given
   * {@link MethodDescriptor}. The returned {@link ClientCall} does not trigger any remote
   * behavior until {@link ClientCall#start(ClientCall.Listener, Metadata)} is
   * invoked.
   *
   * @param methodDescriptor describes the name and parameter types of the operation to call.
   * @param callOptions runtime options to be applied to this call.
   * @return a {@link ClientCall} bound to the specified method.
   * @since 1.0.0
   */
  public abstract <RequestT, ResponseT> ClientCall<RequestT, ResponseT> newCall(
      MethodDescriptor<RequestT, ResponseT> methodDescriptor, CallOptions callOptions);

  /**
   * The authority of the destination this channel connects to. Typically this is in the format
   * {@code host:port}.
   *
   * @since 1.0.0
   */
  public abstract String authority();
}