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https://issues.apache.org/jira/browse/NIFI-1808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15291546#comment-15291546
]
ASF GitHub Bot commented on NIFI-1808:
--------------------------------------
Github user JPercivall commented on a diff in the pull request:
https://github.com/apache/nifi/pull/392#discussion_r63918463
--- Diff:
nifi-nar-bundles/nifi-mqtt-bundle/nifi-mqtt-processors/src/main/java/org/apache/nifi/processors/mqtt/PublishMQTT.java
---
@@ -0,0 +1,237 @@
+/*
+ * 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.annotation.behavior.SupportsBatching;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.expression.AttributeExpression;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+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.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.InputStreamCallback;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processors.mqtt.common.AbstractMQTTProcessor;
+import org.apache.nifi.stream.io.StreamUtils;
+import org.eclipse.paho.client.mqttv3.MqttCallback;
+import org.eclipse.paho.client.mqttv3.MqttException;
+import org.eclipse.paho.client.mqttv3.MqttMessage;
+import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.io.InputStream;
+import java.io.IOException;
+
+@SupportsBatching
+@InputRequirement(Requirement.INPUT_REQUIRED)
+@Tags({"publish", "MQTT", "IOT"})
+@CapabilityDescription("Publishes a message to an MQTT topic")
+@SeeAlso({ConsumeMQTT.class})
+public class PublishMQTT extends AbstractMQTTProcessor {
+
+ public static final PropertyDescriptor PROP_TOPIC = new
PropertyDescriptor.Builder()
+ .name("Topic")
+ .description("The topic to publish the message to.")
+ .expressionLanguageSupported(true)
+ .required(true)
+
.addValidator(StandardValidators.createAttributeExpressionLanguageValidator(AttributeExpression.ResultType.STRING,
true))
+ .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 send the message
with. Accepts three values '0', '1' and '2'; '0' for 'at most once', '1' for
'at least once', '2' for 'exactly once'. " +
+ "Expression language is allowed in order to support
publishing messages with different QoS but the end value of the property must
be either '0', '1' or '2'. ")
+ .required(true)
+ .expressionLanguageSupported(true)
+ .addValidator(QOS_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor PROP_RETAIN = new
PropertyDescriptor.Builder()
+ .name("Retain Message")
+ .description("Whether or not the retain flag should be set on
the MQTT message.")
+ .required(true)
+ .expressionLanguageSupported(true)
+ .addValidator(RETAIN_VALIDATOR)
+ .build();
+
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder()
+ .name("success")
+ .description("FlowFiles that are sent successfully to the
destination are transferred to this relationship.")
+ .build();
+ public static final Relationship REL_FAILURE = new
Relationship.Builder()
+ .name("failure")
+ .description("FlowFiles that failed to send to the destination
are transferred to this relationship.")
+ .build();
+
+ private static final List<PropertyDescriptor> descriptors;
+ private static final Set<Relationship> relationships;
+
+ static {
+ final List<PropertyDescriptor> innerDescriptorsList =
getAbstractPropertyDescriptors();
+ innerDescriptorsList.add(PROP_TOPIC);
+ innerDescriptorsList.add(PROP_QOS);
+ innerDescriptorsList.add(PROP_RETAIN);
+ descriptors = Collections.unmodifiableList(innerDescriptorsList);
+
+ final Set<Relationship> innerRelationshipsSet = new HashSet<>();
+ innerRelationshipsSet.add(REL_SUCCESS);
+ innerRelationshipsSet.add(REL_FAILURE);
+ relationships = Collections.unmodifiableSet(innerRelationshipsSet);
+ }
+
+ @Override
+ protected void init(final ProcessorInitializationContext context) {
+ logger = getLogger();
+ }
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ return relationships;
+ }
+
+ @Override
+ public final List<PropertyDescriptor>
getSupportedPropertyDescriptors() {
+ return descriptors;
+ }
+
+ @OnScheduled
+ public void onScheduled(final ProcessContext context) {
+ buildClient(context);
+ }
+
+ @OnStopped
+ public void onStop(final ProcessContext context) {
+ try {
+ synchronized (mqttClientConnectLock) {
+ if (mqttClient != null && mqttClient.isConnected()) {
+ mqttClient.disconnect();
+ 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 {
+ FlowFile flowfile = session.get();
+ if (flowfile == null) {
+ return;
+ }
+
+ if(mqttClient == null || !mqttClient.isConnected()){
+ logger.info("Was disconnected from client or was never
connected, attempting to connect.");
+ synchronized (mqttClientConnectLock){
--- End diff --
I agree that the synch block here should be removed since the reconnect
already does it.
I disagree that synchronization is only needed in the OnTrigger. The
OnUnScheduled method will by definition have the potential to run while an
OnTrigger is running so it will need the synchronization. Also there is no real
detriment to doing synchronization in the other methods and will help cover the
instances where unusual concurrency situations happen.
> 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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