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https://issues.apache.org/jira/browse/NIFI-1808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15269093#comment-15269093
]
ASF GitHub Bot commented on NIFI-1808:
--------------------------------------
Github user olegz commented on a diff in the pull request:
https://github.com/apache/nifi/pull/392#discussion_r61917246
--- Diff:
nifi-nar-bundles/nifi-mqtt-bundle/nifi-mqtt-processors/src/main/java/org/apache/nifi/processors/mqtt/SubscribeMQTT.java
---
@@ -0,0 +1,301 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.nifi.processors.mqtt;
+
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.PropertyValue;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnUnscheduled;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.logging.ProcessorLog;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessorInitializationContext;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.io.OutputStreamCallback;
+
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.mqtt.common.AbstractMQTTProcessor;
+import org.apache.nifi.processors.mqtt.common.MQTTQueueMessage;
+import org.apache.nifi.ssl.SSLContextService;
+import org.eclipse.paho.client.mqttv3.MqttCallback;
+import org.eclipse.paho.client.mqttv3.MqttClient;
+import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
+import org.eclipse.paho.client.mqttv3.MqttException;
+import org.eclipse.paho.client.mqttv3.MqttMessage;
+import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
+import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Properties;
+import java.util.Set;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.io.OutputStream;
+import java.io.IOException;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+
+@Tags({"subscribe", "MQTT", "IOT"})
+@CapabilityDescription("Subscribes to a topic and receives messages from
an MQTT broker")
+@SeeAlso({PublishMQTT.class})
+@WritesAttributes({@WritesAttribute(attribute="broker", description="MQTT
broker that was the message source"),
+ @WritesAttribute(attribute="topic", description="MQTT topic on which
message was received"),
+ @WritesAttribute(attribute="qos", description="The quality of service
for this message."),
+ @WritesAttribute(attribute="isDuplicate", description="Whether or not
this message might be a duplicate of one which has already been received."),
+ @WritesAttribute(attribute="isRetained", description="Whether or not
this message was from a current publisher, or was \"retained\" by the server as
the last message published on the topic.")})
+public class SubscribeMQTT extends AbstractMQTTProcessor {
+
+ public static final PropertyDescriptor PROP_TOPIC_FILTER = new
PropertyDescriptor.Builder()
+ .name("Topic Filter")
+ .description("The MQTT topic filter to designate the topics to
subscribe to.")
+ .required(true)
+ .expressionLanguageSupported(false)
+ .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor PROP_QOS = new
PropertyDescriptor.Builder()
+ .name("Quality of Service(QoS)")
+ .description("The Quality of Service(QoS) to receive the
message with. Accepts three values '0', '1' and '2'; '0' for 'at most once',
'1' for 'at least once', '2' for 'exactly once'.")
+ .required(true)
+ .allowableValues("0", "1", "2")
+ .build();
+
+
+ public static final PropertyDescriptor PROP_MAX_QUEUE_SIZE = new
PropertyDescriptor.Builder()
+ .name("Max Queue Size")
+ .description("The MQTT messages are always being sent to
subscribers on a topic. If the 'Run Schedule' is significantly behind the rate
at which the messages are arriving to this " +
+ "processor then a back up can occur. This property
specifies the maximum number of messages this processor will hold in memory at
one time.")
+ .required(true)
+
.addValidator(StandardValidators.NON_NEGATIVE_INTEGER_VALIDATOR)
+ .build();
+
+ private String broker;
+ private ProcessorLog logger;
+ private MqttConnectOptions connOpts;
+ private MqttClient mqttClient;
+ private final Object mqttClientLock = new Object();
+ private ScheduledExecutorService autoReconnectExecutor;
+ private final Object autoReconnectLock = new Object();
+ private ScheduledFuture<?> autoReconnectScheduledFuture;
+ private static int AUTO_RECONNECT_PERIOD = 5;
+ private static int DISCONNECT_TIMEOUT = 5000;
+ private long maxQueueSize;
+
+ private MemoryPersistence persistence = new MemoryPersistence();
+
+ LinkedBlockingQueue<MQTTQueueMessage> mqttQueue = new
LinkedBlockingQueue<>();
+
+ public static final Relationship REL_MESSAGE = new
Relationship.Builder()
+ .name("Message")
+ .description("The MQTT message output")
+ .build();
+
+ private List<PropertyDescriptor> descriptors;
+
+ private Set<Relationship> relationships;
+
+ @Override
+ protected void init(final ProcessorInitializationContext context) {
+ logger = getLogger();
+ final List<PropertyDescriptor> descriptors =
getAbstractPropertyDescriptors();
+ descriptors.add(PROP_TOPIC_FILTER);
+ descriptors.add(PROP_QOS);
+ descriptors.add(PROP_MAX_QUEUE_SIZE);
+
+ this.descriptors = Collections.unmodifiableList(descriptors);
+
+ final Set<Relationship> relationships = new
HashSet<Relationship>();
+ relationships.add(REL_MESSAGE);
+ this.relationships = Collections.unmodifiableSet(relationships);
+ }
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ return this.relationships;
+ }
+
+ @Override
+ public final List<PropertyDescriptor>
getSupportedPropertyDescriptors() {
+ return descriptors;
+ }
+
+ @OnScheduled
+ public void onScheduled(final ProcessContext context) {
+ try {
+ maxQueueSize =
context.getProperty(PROP_MAX_QUEUE_SIZE).asLong();
+
+ broker = context.getProperty(PROP_BROKER_URI).getValue();
+ String clientID =
context.getProperty(PROP_CLIENTID).getValue();
+
+ connOpts = new MqttConnectOptions();
+ connOpts.setCleanSession(true);
+
+ PropertyValue sslProp =
context.getProperty(PROP_SSL_CONTEXT_SERVICE);
+ if (sslProp.isSet()) {
+ Properties sslProps =
transformSSLContextService((SSLContextService) sslProp.asControllerService());
+ connOpts.setSSLProperties(sslProps);
+ }
+
+ PropertyValue lastWillTopicProp =
context.getProperty(PROP_LAST_WILL_TOPIC);
+ if (lastWillTopicProp.isSet()){
+ PropertyValue lastWillMessage =
context.getProperty(PROP_LAST_WILL_TOPIC);
+ PropertyValue lastWillRetain =
context.getProperty(PROP_LAST_WILL_TOPIC);
+ connOpts.setWill(lastWillTopicProp.getValue(),
lastWillMessage.getValue().getBytes(), LAST_WILL_QOS, lastWillRetain.isSet() ?
lastWillRetain.asBoolean() : false);
+ }
+
+ PropertyValue usernameProp =
context.getProperty(PROP_USERNAME);
+ if(usernameProp.isSet()) {
+ connOpts.setUserName(usernameProp.getValue());
+
connOpts.setPassword(context.getProperty(PROP_PASSWORD).getValue().toCharArray());
+ }
+
+ String topicFilter =
context.getProperty(PROP_TOPIC_FILTER).getValue();
+ synchronized (mqttClientLock) {
+ mqttClient = new MqttClient(broker, clientID, persistence);
+
+ mqttClient.setCallback(new SubscribeMQTTCallback());
+ getLogger().info("Connecting to broker: " + broker);
+ mqttClient.connect(connOpts);
+ mqttClient.subscribe(topicFilter,
context.getProperty(PROP_QOS).asInteger());
+ }
+ autoReconnectExecutor = new ScheduledThreadPoolExecutor(1);
+ } catch(MqttException me) {
+ getLogger().error("msg "+me.getMessage());
+ }
+ }
+
+ @OnUnscheduled
+ public void onUnscheduled(final ProcessContext context) {
+ try {
+ synchronized (mqttClientLock) {
+ if(mqttClient != null && mqttClient.isConnected()) {
+ mqttClient.disconnect(DISCONNECT_TIMEOUT);
+ }
+ }
+ synchronized (autoReconnectLock) {
+ if(autoReconnectScheduledFuture != null &&
!autoReconnectScheduledFuture.isCancelled()) {
+ logger.debug("Stopping the scheduled future
auto-reconnecter");
+ autoReconnectScheduledFuture.cancel(true);
+ }
+ if (autoReconnectExecutor != null) {
+ logger.debug("Shutting down the auto-reconnect
executor service");
+ autoReconnectExecutor.shutdown();
+ }
+ }
+ logger.info("Disconnected the MQTT client.");
+ } catch(MqttException me) {
+ logger.error("Failed when disconnecting the MQTT client.", me);
+ }
+ }
+
+ @Override
+ public void onTrigger(final ProcessContext context, final
ProcessSession session) throws ProcessException {
+
+ if (mqttQueue.isEmpty()) {
+ return;
--- End diff --
Also, as commented before, should we yield here?
> Create General MQTT Processors
> ------------------------------
>
> Key: NIFI-1808
> URL: https://issues.apache.org/jira/browse/NIFI-1808
> Project: Apache NiFi
> Issue Type: Improvement
> Reporter: Joseph Percivall
> Assignee: Joseph Percivall
>
> MQTT[1] is a great "Internet of Things" (IoT) connectivity protocol that
> implementing processors for would allow NiFi to continue expanding into the
> IoT domain. A prime opportunity would be to use in conjunction with Apache
> NiFi - MiNiFi.
> [1] http://mqtt.org/
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