001/*-
002 * #%L
003 * HAPI FHIR Subscription Server
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.jpa.subscription.api;
021
022import jakarta.annotation.Nullable;
023import org.hl7.fhir.instance.model.api.IBaseResource;
024
025/**
026 * This is used by "message" type subscriptions to provide a key to the message wrapper before submitting it to the channel
027 */
028public interface ISubscriptionMessageKeySvc {
029        /**
030         *  Given an {@link IBaseResource}, return a key that can be used to identify the message. This key will be used to
031         *  partition the message into a queue.
032         *
033         * @param thePayloadResource the payload resource.
034         * @return the key or null.
035         */
036        @Nullable
037        String getMessageKeyOrNull(IBaseResource thePayloadResource);
038}