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https://issues.apache.org/jira/browse/NIFI-1808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15287315#comment-15287315
]
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_r63584682
--- Diff:
nifi-nar-bundles/nifi-mqtt-bundle/nifi-mqtt-processors/src/main/java/org/apache/nifi/processors/mqtt/PublishMQTT.java
---
@@ -0,0 +1,239 @@
+/*
+ * 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(QoSValidator)
+ .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(RetainValidator)
+ .build();
+
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder()
+ .name("success")
+ .description("FlowFiles that are sent successfully to the
destination are sent out this relationship.")
+ .build();
+ public static final Relationship REL_FAILURE = new
Relationship.Builder()
+ .name("failure")
+ .description("FlowFiles that failed to send to the destination
are sent out 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){
+ try {
+ reconnect();
+ } catch (MqttException e) {
+ context.yield();
+ session.transfer(flowfile, REL_FAILURE);
+ logger.error("MQTT client is disconnected and
re-connecting failed. Transferring FlowFile to fail and yielding", e);
+ return;
+ }
+ }
+ }
+
+ // get the MQTT topic
+ String topic =
context.getProperty(PROP_TOPIC).evaluateAttributeExpressions(flowfile).getValue();
+
+ if (topic == null || topic.isEmpty()) {
+ logger.warn("Evaluation of the topic property returned null or
evaluated to be empty, routing to failure");
+ session.transfer(flowfile, REL_FAILURE);
+ return;
+ }
+
+ // do the read
+ final byte[] messageContent = new byte[(int) flowfile.getSize()];
+ session.read(flowfile, new InputStreamCallback() {
+ @Override
+ public void process(final InputStream in) throws IOException {
+ StreamUtils.fillBuffer(in, messageContent, true);
+ }
+ });
+
+ int qos =
context.getProperty(PROP_QOS).evaluateAttributeExpressions(flowfile).asInteger();
+ final MqttMessage mqttMessage = new MqttMessage(messageContent);
+ mqttMessage.setQos(qos);
+ mqttMessage.setPayload(messageContent);
+
mqttMessage.setRetained(context.getProperty(PROP_RETAIN).evaluateAttributeExpressions(flowfile).asBoolean());
--- End diff --
The evaluation will always return a property value (even if it evaluates to
a blank string)[1]. Then when it is evaluated as a boolean [2] it does a null
check and passes it to Boolean.parseBoolean() which does another null check and
returns false if the value is not equal to "true".
[1]
https://github.com/apache/nifi/blob/f378ee902127bd29b168c9bb15e991abe4eab0fa/nifi-commons/nifi-expression-language/src/main/java/org/apache/nifi/attribute/expression/language/StandardPropertyValue.java#L137
[2]
https://github.com/apache/nifi/blob/f378ee902127bd29b168c9bb15e991abe4eab0fa/nifi-commons/nifi-expression-language/src/main/java/org/apache/nifi/attribute/expression/language/StandardPropertyValue.java#L73
> 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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