
001/*- 002 * #%L 003 * HAPI FHIR Storage api 004 * %% 005 * Copyright (C) 2014 - 2025 Smile CDR, Inc. 006 * %% 007 * Licensed under the Apache License, Version 2.0 (the "License"); 008 * you may not use this file except in compliance with the License. 009 * You may obtain a copy of the License at 010 * 011 * http://www.apache.org/licenses/LICENSE-2.0 012 * 013 * Unless required by applicable law or agreed to in writing, software 014 * distributed under the License is distributed on an "AS IS" BASIS, 015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 016 * See the License for the specific language governing permissions and 017 * limitations under the License. 018 * #L% 019 */ 020package ca.uhn.fhir.broker.api; 021 022import ca.uhn.fhir.rest.server.messaging.IMessage; 023 024/** 025 * Receives messages from a Message Broker. 026 * 027 * @param <T> The type of messages received by this consumer 028 */ 029public interface IChannelConsumer<T> extends AutoCloseable { 030 /** 031 * @return the name of the topic or queue that this consumer is consuming from 032 */ 033 String getChannelName(); 034 035 /** 036 * Start the thread(s) that will be consuming messages 037 * @throws ChannelConsumerStartFailureException if the consumer fails to start (e.g. if it fails to connect to the broker) 038 */ 039 void start(); 040 /** 041 * Close this consumer's listener and this consumer, releasing any resources. 042 */ 043 void close(); 044 045 /** 046 * @return true if this consumer is closed 047 */ 048 boolean isClosed(); 049 050 /** 051 * @return the type of messages that will be delivered to this consumer 052 */ 053 Class<? extends IMessage<T>> getMessageType(); 054 055 /** 056 * @return the {@link IMessageListener} this consumer is sending messages to (i.e. the one it was created with). 057 */ 058 IMessageListener<T> getMessageListener(); 059 060 /** 061 * Pause requesting new messages from the broker until resume() is called. 062 */ 063 default void pause() { 064 throw new UnsupportedOperationException(); 065 } 066 067 /** 068 * Resume requesting messages from the broker. 069 */ 070 default void resume() { 071 throw new UnsupportedOperationException(); 072 } 073 074 /** 075 * Consumers should call this method at the top of any method that attempts to use the consumer 076 */ 077 default void checkState() { 078 if (isClosed()) { 079 throw new BrokerConsumerClosedException( 080 "Attempted to use a closed " + this.getClass().getSimpleName() + ": " + this); 081 } 082 } 083}