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From mosermw <...@git.apache.org>
Subject [GitHub] nifi pull request: NIFI-1808 Creating general MQTT processors
Date Fri, 13 May 2016 17:56:14 GMT
Github user mosermw commented on a diff in the pull request:

    https://github.com/apache/nifi/pull/392#discussion_r63224728
  
    --- Diff: nifi-nar-bundles/nifi-mqtt-bundle/nifi-mqtt-processors/src/main/java/org/apache/nifi/processors/mqtt/PublishMQTT.java
---
    @@ -0,0 +1,288 @@
    +/*
    + * 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.components.PropertyValue;
    +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.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.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.ssl.SSLContextService;
    +import org.apache.nifi.stream.io.StreamUtils;
    +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.Arrays;
    +import java.util.Collections;
    +import java.util.HashSet;
    +import java.util.List;
    +import java.util.Properties;
    +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({SubscribeMQTT.class})
    +public class PublishMQTT extends AbstractMQTTProcessor {
    +
    +    private String broker;
    +    private MemoryPersistence persistence = new MemoryPersistence();
    +    private MqttClient mqttClient;
    +    private final Object mqttClientLock = new Object();
    +
    +    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'.")
    +            .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 PropertyDescriptor PROP_TIMEOUT = new PropertyDescriptor.Builder()
    +            .name("QoS Timeout")
    +            .description("How many milliseconds to wait for the broker to acknowledge
delivery of a message before routing the message back to the source queue for retry. Only
applicable " +
    +                    "when QoS is 1 or 2")
    +            .required(true)
    +            .addValidator(StandardValidators.NON_NEGATIVE_INTEGER_VALIDATOR)
    +            .build();
    +
    +    private List<PropertyDescriptor> descriptors;
    +
    +    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 Set<Relationship> relationships;
    +    private ProcessorLog logger;
    +    private MqttConnectOptions connOpts;
    +
    +    @Override
    +    protected void init(final ProcessorInitializationContext context) {
    +        logger = getLogger();
    +        final List<PropertyDescriptor> descriptors = getAbstractPropertyDescriptors();
    +        descriptors.add(PROP_TOPIC);
    +        descriptors.add(PROP_QOS);
    +        descriptors.add(PROP_RETAIN);
    +        descriptors.add(PROP_TIMEOUT);
    +        this.descriptors = Collections.unmodifiableList(descriptors);
    +
    +        final Set<Relationship> relationships = new HashSet<Relationship>();
    +        relationships.add(REL_SUCCESS);
    +        relationships.add(REL_FAILURE);
    +        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 {
    +            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());
    +            }
    +
    +            synchronized (mqttClientLock) {
    +                mqttClient = new MqttClient(broker, clientID, persistence);
    +
    +                mqttClient.setCallback(new PublishMQTTCallback());
    +                getLogger().info("Connecting to broker: " + broker);
    +                mqttClient.connect(connOpts);
    +            }
    +        } catch(MqttException me) {
    +            logger.error("Failed to initialize the connection to the  "+me.getMessage());
    +        }
    +    }
    +
    +    @OnStopped
    +    public void onStop(final ProcessContext context) {
    +        try {
    +            synchronized (mqttClientLock) {
    +                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;
    +        }
    --- End diff --
    
    I realize I'm really late to this discussion, but flowfile can be null on an INPUT_REQUIRED
processor is when it's configured with >1 Concurrent Tasks.  If 1 flowfile arrives in an
input queue, then the framework can sometimes assign more than 1 thread to run this processor's
onTrigger().  The first thread will get the flowfile and the second thread will get a null
flowfile and should just return.  The framework won't schedule this processor again until
another flowfile arrives on an input queue.


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