Github user olegz commented on a diff in the pull request: https://github.com/apache/nifi/pull/271#discussion_r56106557 --- Diff: nifi-nar-bundles/nifi-spring-bundle/nifi-spring-processors/src/main/java/org/apache/nifi/spring/SpringContextProcessor.java --- @@ -0,0 +1,382 @@ +/* + * 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.spring; + +import java.io.File; +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Set; +import java.util.concurrent.TimeUnit; + +import org.apache.nifi.annotation.behavior.TriggerWhenEmpty; +import org.apache.nifi.annotation.documentation.CapabilityDescription; +import org.apache.nifi.annotation.documentation.Tags; +import org.apache.nifi.annotation.lifecycle.OnScheduled; +import org.apache.nifi.annotation.lifecycle.OnStopped; +import org.apache.nifi.components.PropertyDescriptor; +import org.apache.nifi.components.ValidationContext; +import org.apache.nifi.components.ValidationResult; +import org.apache.nifi.components.Validator; +import org.apache.nifi.flowfile.FlowFile; +import org.apache.nifi.processor.AbstractProcessor; +import org.apache.nifi.processor.ProcessContext; +import org.apache.nifi.processor.ProcessSession; +import org.apache.nifi.processor.Processor; +import org.apache.nifi.processor.Relationship; +import org.apache.nifi.processor.exception.ProcessException; +import org.apache.nifi.processor.io.InputStreamCallback; +import org.apache.nifi.processor.io.OutputStreamCallback; +import org.apache.nifi.processor.util.StandardValidators; +import org.apache.nifi.spring.SpringDataExchanger.SpringResponse; +import org.apache.nifi.stream.io.StreamUtils; +import org.apache.nifi.util.FormatUtils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.springframework.messaging.Message; +import org.springframework.messaging.MessageChannel; +import org.springframework.messaging.PollableChannel; + +/** + * Implementation of {@link Processor} capable of sending and receiving data + * from application defined in Spring Application context. It does so via + * predefined in/out {@link MessageChannel}s (see spring-messaging module of + * Spring). Once such channels are defined user is free to implement the rest of + * the application any way they wish (e.g., custom code and/or using frameworks + * such as Spring Integration or Camel). + * <p> + * The requirement and expectations for channel types are: + * <ul> + * <li>Input channel must be of type {@link MessageChannel} and named "fromNiFi" + * (see {@link SpringNiFiConstants#FROM_NIFI})</li> + * <li>Output channel must be of type {@link PollableChannel} and named "toNiFi" + * (see {@link SpringNiFiConstants#TO_NIFI})</li> + * </ul> + * </p> + * Below is the example of sample configuration: + * + * <pre> + * <?xml version="1.0" encoding="UTF-8"?> + * <beans xmlns="http://www.springframework.org/schema/beans" + * xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + * xmlns:int="http://www.springframework.org/schema/integration" + * xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd + * http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration-4.2.xsd"> + * + * <int:channel id="fromNiFi"/> + * + * . . . . . + * + * <int:channel id="toNiFi"> + * <int:queue/> + * </int:channel> + * + * </beans> + * </pre> + * <p> + * Defining {@link MessageChannel} is optional. That's why this processor + * supports 3 modes of interaction with Spring Application Context: + * <ul> + * <li>Headless â no channels are defined therefore nothing is sent to or + * received from such Application Contexts (i.e., some monitoring app).</li> + * <li>One way (NiFi -> Spring or Spring -> NiFi) - depends on existence + * of one of "fromNiFi" or "toNiFi" channel in the Spring Application Context. + * </li> + * <li>Bi-directional (NiFi -> Spring -> Nifi or Spring -> NiFi -> + * Spring) - depends on existence of both "fromNiFi" and "toNiFi" channels in + * the Spring Application Context</li> + * </ul> + * + * </p> + * <p> + * To create an instance of the ApplicationConetxt this processor requires user + * to provide configuration file path and the path to the resources that needs + * to be added to the classpath of ApplicationContext. This essentially allows + * user to package their Spring Application any way they want as long as + * everything it requires is available on the classpath. + * </p> + * <p> + * Data exchange between Spring and NiFi relies on simple mechanism which is + * exposed via {@link SpringDataExchanger}; {@link FlowFile}s's content is + * converted to primitive representation that can be easily wrapped in Spring + * {@link Message}. The requirement imposed by this Processor is to send/receive + * {@link Message} with <i>payload</i> of type <i>byte[]</i> and headers of type + * <i>Map<String, Object></i>. This is primarily for simplicity and type + * safety. Converters and Transformers could be used by either side to change + * representation of the content that is being exchanged between NiFi and + * Spring. + */ +@TriggerWhenEmpty +@Tags({ "Spring", "Message", "Get", "Put", "Integration" }) +@CapabilityDescription("A Processor that supports sending and receiving data from application defined in " + + "Spring Application Context via predefined in/out MessageChannels.") +public class SpringContextProcessor extends AbstractProcessor { + private final Logger logger = LoggerFactory.getLogger(SpringContextProcessor.class); + + public static final PropertyDescriptor CTX_CONFIG_NAME = new PropertyDescriptor.Builder() + .name("Application Context config path") + .description("The path to the Spring Application Context configuration file relative to the classpath") + .required(true) + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .build(); + public static final PropertyDescriptor CTX_LIB_PATH = new PropertyDescriptor.Builder() + .name("Application Context class path") + .description("Path to the directory with resources (i.e., JARs, configuration files etc.) required to be on " + + "the classpath of the ApplicationContext.") + .addValidator(new ClientLibValidator()) + .required(true) + .build(); + public static final PropertyDescriptor SEND_TIMEOUT = new PropertyDescriptor.Builder() + .name("Send Timeout") + .description("Timeout for sending data to Spring Application Context. Defaults to 0.") + .required(false) + .addValidator(StandardValidators.TIME_PERIOD_VALIDATOR) + .build(); + public static final PropertyDescriptor RECEIVE_TIMEOUT = new PropertyDescriptor.Builder() + .name("Receive Timeout") + .description("Timeout for receiving date from Spring context. Defaults to 0.") + .required(false) + .addValidator(StandardValidators.TIME_PERIOD_VALIDATOR) + .build(); + + // ==== + + public static final Relationship REL_SUCCESS = new Relationship.Builder().name("success") + .description( + "All FlowFiles that are successfully received from Spring Application Context are routed to this relationship") + .build(); + public static final Relationship REL_FAILURE = new Relationship.Builder().name("failure") + .description( + "All FlowFiles that cannot be sent to Spring Application Context are routed to this relationship") + .build(); + + private final static Set<Relationship> relationships; + + private final static List<PropertyDescriptor> propertyDescriptors; + + // ======= + + private volatile String applicationContextConfigFileName; + + private volatile String applicationContextLibPath; + + private volatile long sendTimeout; + + private volatile long receiveTimeout; + + private volatile SpringDataExchanger exchanger; + + static { + List<PropertyDescriptor> _propertyDescriptors = new ArrayList<>(); + _propertyDescriptors.add(CTX_CONFIG_NAME); + _propertyDescriptors.add(CTX_LIB_PATH); + _propertyDescriptors.add(SEND_TIMEOUT); + _propertyDescriptors.add(RECEIVE_TIMEOUT); + propertyDescriptors = Collections.unmodifiableList(_propertyDescriptors); + + Set<Relationship> _relationships = new HashSet<>(); + _relationships.add(REL_SUCCESS); + _relationships.add(REL_FAILURE); + relationships = Collections.unmodifiableSet(_relationships); + } + + /** + * + */ + @Override + public Set<Relationship> getRelationships() { + return relationships; + } + + /** + * + */ + @OnScheduled + public void initializeSpringContext(ProcessContext processContext) { + this.applicationContextConfigFileName = processContext.getProperty(CTX_CONFIG_NAME).getValue(); + this.applicationContextLibPath = processContext.getProperty(CTX_LIB_PATH).getValue(); + + String stStr = processContext.getProperty(SEND_TIMEOUT).getValue(); + this.sendTimeout = stStr == null ? 0 : FormatUtils.getTimeDuration(stStr, TimeUnit.MILLISECONDS); + + String rtStr = processContext.getProperty(RECEIVE_TIMEOUT).getValue(); + this.receiveTimeout = rtStr == null ? 0 : FormatUtils.getTimeDuration(rtStr, TimeUnit.MILLISECONDS); + + try { + if (logger.isDebugEnabled()) { + logger.debug( + "Initializing Spring Application Context defined in " + this.applicationContextConfigFileName); + } + this.exchanger = SpringContextFactory.createSpringContextDelegate(this.applicationContextLibPath, + this.applicationContextConfigFileName); + } catch (Exception e) { + throw new IllegalStateException("Failed while initializing Spring Application Context", e); + } + if (logger.isInfoEnabled()) { + logger.info("Successfully initialized Spring Application Context defined in " + + this.applicationContextConfigFileName); + } + } + + /** + * Will close the 'exchanger' which in turn will close both Spring + * Application Context and the ClassLoader that loaded it allowing new + * instance of Spring Application Context to be created upon the next start + * (which may have an updated classpath and functionality) without + * restarting NiFi. + */ + @OnStopped + public void closeSpringContext(ProcessContext processContext) { + if (this.exchanger != null) { + try { + if (logger.isDebugEnabled()) { + logger.debug( + "Closing Spring Application Context defined in " + this.applicationContextConfigFileName); + } + this.exchanger.close(); + if (logger.isInfoEnabled()) { + logger.info("Successfully closed Spring Application Context defined in " + + this.applicationContextConfigFileName); + } + } catch (IOException e) { + getLogger().warn("Failed while closing Spring Application Context", e); + } + } + } + + /** + * + */ + @Override + public void onTrigger(ProcessContext context, ProcessSession processSession) throws ProcessException { + FlowFile flowFileToProcess = processSession.get(); + if (flowFileToProcess != null) { + this.sendToSpring(flowFileToProcess, context, processSession); --- End diff -- Good point
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