1 /* 2 * Copyright 2014 The gRPC Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package io.grpc; 18 19 import javax.annotation.concurrent.ThreadSafe; 20 21 /** 22 * A virtual connection to a conceptual endpoint, to perform RPCs. A channel is free to have zero or 23 * many actual connections to the endpoint based on configuration, load, etc. A channel is also free 24 * to determine which actual endpoints to use and may change it every RPC, permitting client-side 25 * load balancing. Applications are generally expected to use stubs instead of calling this class 26 * directly. 27 * 28 * <p>Applications can add common cross-cutting behaviors to stubs by decorating Channel 29 * implementations using {@link ClientInterceptor}. It is expected that most application 30 * code will not use this class directly but rather work with stubs that have been bound to a 31 * Channel that was decorated during application initialization. 32 */ 33 @ThreadSafe 34 public abstract class Channel { 35 /** 36 * Create a {@link ClientCall} to the remote operation specified by the given 37 * {@link MethodDescriptor}. The returned {@link ClientCall} does not trigger any remote 38 * behavior until {@link ClientCall#start(ClientCall.Listener, Metadata)} is 39 * invoked. 40 * 41 * @param methodDescriptor describes the name and parameter types of the operation to call. 42 * @param callOptions runtime options to be applied to this call. 43 * @return a {@link ClientCall} bound to the specified method. 44 * @since 1.0.0 45 */ newCall( MethodDescriptor<RequestT, ResponseT> methodDescriptor, CallOptions callOptions)46 public abstract <RequestT, ResponseT> ClientCall<RequestT, ResponseT> newCall( 47 MethodDescriptor<RequestT, ResponseT> methodDescriptor, CallOptions callOptions); 48 49 /** 50 * The authority of the destination this channel connects to. Typically this is in the format 51 * {@code host:port}. 52 * 53 * @since 1.0.0 54 */ authority()55 public abstract String authority(); 56 } 57