Java tutorial
package ca.uhn.fhir.jpa.subscription; /* * #%L * HAPI FHIR JPA Server * %% * Copyright (C) 2014 - 2015 University Health Network * %% * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * #L% */ import java.io.IOException; import java.util.List; import java.util.concurrent.ScheduledFuture; import javax.annotation.PostConstruct; import javax.annotation.PreDestroy; import org.apache.http.NameValuePair; import org.apache.http.client.utils.URLEncodedUtils; import org.hl7.fhir.instance.model.api.IBaseResource; import org.hl7.fhir.instance.model.api.IIdType; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; import org.springframework.scheduling.TaskScheduler; import org.springframework.web.socket.CloseStatus; import org.springframework.web.socket.TextMessage; import org.springframework.web.socket.WebSocketSession; import org.springframework.web.socket.handler.TextWebSocketHandler; import ca.uhn.fhir.context.FhirContext; import ca.uhn.fhir.jpa.dao.IFhirResourceDaoSubscription; import ca.uhn.fhir.model.dstu2.resource.Subscription; import ca.uhn.fhir.model.dstu2.valueset.SubscriptionChannelTypeEnum; import ca.uhn.fhir.model.dstu2.valueset.SubscriptionStatusEnum; import ca.uhn.fhir.model.primitive.IdDt; import ca.uhn.fhir.rest.server.Constants; import ca.uhn.fhir.rest.server.EncodingEnum; import ca.uhn.fhir.rest.server.exceptions.ResourceNotFoundException; import ca.uhn.fhir.rest.server.exceptions.UnprocessableEntityException; public class SubscriptionWebsocketHandler extends TextWebSocketHandler implements ISubscriptionWebsocketHandler, Runnable { private static final org.slf4j.Logger ourLog = org.slf4j.LoggerFactory .getLogger(SubscriptionWebsocketHandler.class); @Autowired @Qualifier("myFhirContextDstu2") private FhirContext myCtx; private ScheduledFuture<?> myScheduleFuture; private IState myState = new InitialState(); @Autowired private IFhirResourceDaoSubscription<Subscription> mySubscriptionDao; private IIdType mySubscriptionId; private Long mySubscriptionPid; @Autowired private TaskScheduler myTaskScheduler; @Override public void afterConnectionClosed(WebSocketSession theSession, CloseStatus theStatus) throws Exception { super.afterConnectionClosed(theSession, theStatus); ourLog.info("Closing WebSocket connection from {}", theSession.getRemoteAddress()); } @Override public void afterConnectionEstablished(WebSocketSession theSession) throws Exception { super.afterConnectionEstablished(theSession); ourLog.info("Incoming WebSocket connection from {}", theSession.getRemoteAddress()); } protected void handleFailure(Exception theE) { ourLog.error("Failure during communication", theE); } @Override protected void handleTextMessage(WebSocketSession theSession, TextMessage theMessage) throws Exception { ourLog.info("Textmessage: " + theMessage.getPayload()); myState.handleTextMessage(theSession, theMessage); } @Override public void handleTransportError(WebSocketSession theSession, Throwable theException) throws Exception { super.handleTransportError(theSession, theException); ourLog.error("Transport error", theException); } @PostConstruct public void postConstruct() { ourLog.info("Creating scheduled task for subscription websocket connection"); myScheduleFuture = myTaskScheduler.scheduleWithFixedDelay(this, 1000); } @PreDestroy public void preDescroy() { ourLog.info("Cancelling scheduled task for subscription websocket connection"); myScheduleFuture.cancel(true); IState state = myState; if (state != null) { state.closing(); } } @Override public void run() { Long subscriptionPid = mySubscriptionPid; if (subscriptionPid == null) { return; } ourLog.debug("Subscription {} websocket handler polling", subscriptionPid); List<IBaseResource> results = mySubscriptionDao.getUndeliveredResourcesAndPurge(subscriptionPid); if (results.isEmpty() == false) { myState.deliver(results); } } private class BoundDynamicSubscriptionState implements IState { private EncodingEnum myEncoding; private WebSocketSession mySession; public BoundDynamicSubscriptionState(WebSocketSession theSession, EncodingEnum theEncoding) { mySession = theSession; myEncoding = theEncoding; } @Override public void closing() { ourLog.info("Deleting subscription {}", mySubscriptionId); try { mySubscriptionDao.delete(mySubscriptionId); } catch (Exception e) { handleFailure(e); } } @Override public void deliver(List<IBaseResource> theResults) { try { for (IBaseResource nextResource : theResults) { ourLog.info("Sending WebSocket message for resource: {}", nextResource.getIdElement()); String encoded = myEncoding.newParser(myCtx).encodeResourceToString(nextResource); String payload = "add " + mySubscriptionId.getIdPart() + '\n' + encoded; mySession.sendMessage(new TextMessage(payload)); } } catch (IOException e) { handleFailure(e); } } @Override public void handleTextMessage(WebSocketSession theSession, TextMessage theMessage) { try { theSession.sendMessage(new TextMessage("Unexpected client message: " + theMessage.getPayload())); } catch (IOException e) { handleFailure(e); } } } private class BoundStaticSubscipriptionState implements IState { private WebSocketSession mySession; public BoundStaticSubscipriptionState(WebSocketSession theSession) { mySession = theSession; } @Override public void closing() { // nothing } @Override public void deliver(List<IBaseResource> theResults) { try { String payload = "ping " + mySubscriptionId.getIdPart(); ourLog.info("Sending WebSocket message: {}", payload); mySession.sendMessage(new TextMessage(payload)); } catch (IOException e) { handleFailure(e); } } @Override public void handleTextMessage(WebSocketSession theSession, TextMessage theMessage) { try { theSession.sendMessage(new TextMessage("Unexpected client message: " + theMessage.getPayload())); } catch (IOException e) { handleFailure(e); } } } private class InitialState implements IState { private IIdType bindSimple(WebSocketSession theSession, String theBindString) { IdDt id = new IdDt(theBindString); if (!id.hasIdPart() || !id.isIdPartValid()) { try { theSession.close(new CloseStatus(CloseStatus.PROTOCOL_ERROR.getCode(), "Invalid bind request - No ID included")); } catch (IOException e) { handleFailure(e); } return null; } if (id.hasResourceType() == false) { id = id.withResourceType("Subscription"); } try { Subscription subscription = mySubscriptionDao.read(id); mySubscriptionPid = mySubscriptionDao.getSubscriptionTablePidForSubscriptionResource(id); mySubscriptionId = subscription.getIdElement(); myState = new BoundStaticSubscipriptionState(theSession); } catch (ResourceNotFoundException e) { try { theSession.close(new CloseStatus(CloseStatus.PROTOCOL_ERROR.getCode(), "Invalid bind request - Unknown subscription: " + id.getValue())); } catch (IOException e1) { handleFailure(e); } return null; } return id; } private IIdType bingSearch(WebSocketSession theSession, String theRemaining) { Subscription subscription = new Subscription(); subscription.getChannel().setType(SubscriptionChannelTypeEnum.WEBSOCKET); subscription.setStatus(SubscriptionStatusEnum.ACTIVE); subscription.setCriteria(theRemaining); try { String params = theRemaining.substring(theRemaining.indexOf('?') + 1); List<NameValuePair> paramValues = URLEncodedUtils.parse(params, Constants.CHARSET_UTF8, '&'); EncodingEnum encoding = EncodingEnum.JSON; for (NameValuePair nameValuePair : paramValues) { if (Constants.PARAM_FORMAT.equals(nameValuePair.getName())) { EncodingEnum nextEncoding = Constants.FORMAT_VAL_TO_ENCODING.get(nameValuePair.getValue()); if (nextEncoding != null) { encoding = nextEncoding; } } } IIdType id = mySubscriptionDao.create(subscription).getId(); mySubscriptionPid = mySubscriptionDao.getSubscriptionTablePidForSubscriptionResource(id); mySubscriptionId = subscription.getIdElement(); myState = new BoundDynamicSubscriptionState(theSession, encoding); return id; } catch (UnprocessableEntityException e) { ourLog.warn("Failed to bind subscription: " + e.getMessage()); try { theSession.close(new CloseStatus(CloseStatus.PROTOCOL_ERROR.getCode(), "Invalid bind request - " + e.getMessage())); } catch (IOException e2) { handleFailure(e2); } } catch (Exception e) { handleFailure(e); try { theSession.close(new CloseStatus(CloseStatus.PROTOCOL_ERROR.getCode(), "Invalid bind request - No ID included")); } catch (IOException e2) { handleFailure(e2); } } return null; } @Override public void closing() { // nothing } @Override public void deliver(List<IBaseResource> theResults) { throw new IllegalStateException(); } @Override public void handleTextMessage(WebSocketSession theSession, TextMessage theMessage) { String message = theMessage.getPayload(); if (message.startsWith("bind ")) { String remaining = message.substring("bind ".length()); IIdType subscriptionId; if (remaining.contains("?")) { subscriptionId = bingSearch(theSession, remaining); } else { subscriptionId = bindSimple(theSession, remaining); if (subscriptionId == null) { return; } } try { theSession.sendMessage(new TextMessage("bound " + subscriptionId.getIdPart())); } catch (IOException e) { handleFailure(e); } } } } private interface IState { void closing(); void deliver(List<IBaseResource> theResults); void handleTextMessage(WebSocketSession theSession, TextMessage theMessage); } }