Java tutorial
/** * Copyright (C) 2015 Orange * 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. */ package com.francetelecom.clara.cloud.paas.activation.v1.async; import java.util.UUID; import org.apache.commons.lang3.SerializationUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.amqp.core.AmqpTemplate; import org.springframework.amqp.core.Message; import org.springframework.amqp.core.MessageBuilder; import org.springframework.amqp.core.MessageProperties; import org.springframework.amqp.core.MessagePropertiesBuilder; import com.francetelecom.clara.cloud.commons.tasks.TaskStatus; import com.francetelecom.clara.cloud.paas.activation.v1.async.exception.MaxRetryCountExceededException; import com.francetelecom.clara.cloud.paas.activation.v1.async.policy.RetryPolicy; import com.francetelecom.clara.cloud.paas.activation.v1.async.policy.SimpleRetryPolicy; public class AmqpTaskHandler<R, C extends TaskHandlerCallback<R>> implements TaskHandler<R, C> { /** * helper that simplifies synchronous AMQP access code to 'request' queue */ private AmqpTemplate amqpRequestTemplate; /** * helper that simplifies synchronous AMQP access code to 'reply' queue */ private AmqpTemplate amqpReplyTemplate; /** * helper that simplifies synchronous AMQP access code to 'error' queue */ private AmqpTemplate amqpErrorTemplate; /** * injected callback implementation */ private TaskHandlerCallback<R> taskHandlerCallback; /** * retry policy */ private RetryPolicy retryPolicy = new SimpleRetryPolicy(); private static final Logger log = LoggerFactory.getLogger(AmqpTaskHandler.class); @Override public TaskStatus handleRequest(R request, final String communicationId) { log.trace("(0) handleRequest {}", request.toString()); // callback delegation final TaskStatus taskStatus = taskHandlerCallback.handleRequest(request); if (taskStatus.isComplete()) { log.trace("(1) task is complete. no need to poll. Sends task Status to reply queue"); MessageProperties props; props = MessagePropertiesBuilder.newInstance() .setContentType(MessageProperties.CONTENT_TYPE_SERIALIZED_OBJECT) .setMessageId(UUID.randomUUID().toString()).setCorrelationId(communicationId.getBytes()) .build(); Message message = MessageBuilder.withBody(SerializationUtils.serialize(taskStatus)).andProperties(props) .build(); amqpReplyTemplate.send(message); log.trace("(2) message sent to reply queue"); } else { log.trace( "(1) handleRequest status : {} send in amqp queue a 'retry' request used to poll backend service for", taskStatus.toString()); MessageProperties props; props = MessagePropertiesBuilder.newInstance() .setContentType(MessageProperties.CONTENT_TYPE_SERIALIZED_OBJECT) .setMessageId(UUID.randomUUID().toString()).setCorrelationId(communicationId.getBytes()) .setHeader("retryCount", 1).build(); Message message = MessageBuilder.withBody(SerializationUtils.serialize(taskStatus)).andProperties(props) .build(); amqpRequestTemplate.send(message); log.trace("(2) handleRequest send amqp message ended"); } return taskStatus; } @Override public void onTaskPolled(TaskStatus taskStatus, final RetryContext retryContext, final String communicationId) { log.trace("onTaskPolled taskStatus={}", taskStatus.toString()); // callback delegation final TaskStatus t = taskHandlerCallback.onTaskPolled(taskStatus); log.trace("[after] onTaskPolled taskStatus={}", t.toString()); if (t.isComplete()) { log.trace("task is complete. no need to keep polling. Sends task Status to reply queue"); MessageProperties props; props = MessagePropertiesBuilder.newInstance() .setContentType(MessageProperties.CONTENT_TYPE_SERIALIZED_OBJECT) .setMessageId(UUID.randomUUID().toString()).setCorrelationId(communicationId.getBytes()) .build(); Message message = MessageBuilder.withBody(SerializationUtils.serialize(t)).andProperties(props).build(); amqpReplyTemplate.send(message); } else { if (!retryPolicy.canRetry(retryContext.getRetryCount())) { // max retry count exceeded. no need to keep polling. Sends // Exception to error queue log.warn("Max retry count reached: " + retryPolicy.getMaxAttempts()); MessageProperties props = MessagePropertiesBuilder.newInstance() .setContentType(MessageProperties.CONTENT_TYPE_SERIALIZED_OBJECT) .setMessageId(UUID.randomUUID().toString()).setCorrelationId(communicationId.getBytes()) .build(); Message message = MessageBuilder .withBody(SerializationUtils.serialize(new MaxRetryCountExceededException( "Max retry count reached : " + retryPolicy.getMaxAttempts()))) .andProperties(props).build(); amqpErrorTemplate.send(message); } else { try { Thread.sleep(2000); } catch (InterruptedException e) { log.warn("Thread sleeping before sending message back to Request queue has been interrupted."); } log.trace("task is not complete. Must keep polling. Sends task Status to request queue"); MessageProperties props = MessagePropertiesBuilder.newInstance() .setContentType(MessageProperties.CONTENT_TYPE_SERIALIZED_OBJECT) .setMessageId(UUID.randomUUID().toString()).setCorrelationId(communicationId.getBytes()) .setHeader("retryCount", retryContext.getRetryCount() + 1).build(); Message message = MessageBuilder.withBody(SerializationUtils.serialize(t)).andProperties(props) .build(); amqpRequestTemplate.send(message); } } } @Override public void onTaskComplete(TaskStatus taskStatus, String communicationId) { log.trace("onTaskComplete {}", taskStatus.toString()); // callback delegation taskHandlerCallback.onTaskComplete(taskStatus, communicationId); } @Override public void onTaskFailure(Throwable throwable, String communicationId) { log.trace("onTaskFailure {}", throwable.getMessage()); // callback delegation taskHandlerCallback.onFailure(throwable, communicationId); } public void setTaskHandlerCallback(TaskHandlerCallback<R> taskHandlerCallback) { this.taskHandlerCallback = taskHandlerCallback; } public void setRetryPolicy(RetryPolicy retryPolicy) { this.retryPolicy = retryPolicy; } public RetryPolicy getRetryPolicy() { return retryPolicy; } public void setAmqpRequestTemplate(AmqpTemplate rabbitRequestTemplate) { this.amqpRequestTemplate = rabbitRequestTemplate; } public void setAmqpReplyTemplate(AmqpTemplate rabbitReplyTemplate) { this.amqpReplyTemplate = rabbitReplyTemplate; } public void setAmqpErrorTemplate(AmqpTemplate rabbitErrorTemplate) { this.amqpErrorTemplate = rabbitErrorTemplate; } }