Github user trixpan commented on a diff in the pull request: https://github.com/apache/nifi/pull/710#discussion_r71973968 --- Diff: nifi-nar-bundles/nifi-email-bundle/nifi-email-processors/src/main/java/org/apache/nifi/processors/email/AbstractEmailProcessor.java --- @@ -0,0 +1,391 @@ +/* + * 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.email; + +import java.io.IOException; +import java.io.OutputStream; +import java.io.UnsupportedEncodingException; +import java.net.URLEncoder; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.HashSet; +import java.util.List; +import java.util.Map.Entry; +import java.util.Properties; +import java.util.Set; +import java.util.concurrent.ArrayBlockingQueue; +import java.util.concurrent.BlockingQueue; +import java.util.concurrent.TimeUnit; + +import javax.mail.Address; +import javax.mail.Message; +import javax.mail.MessagingException; + +import org.apache.nifi.annotation.lifecycle.OnStopped; +import org.apache.nifi.components.PropertyDescriptor; +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.Relationship; +import org.apache.nifi.processor.exception.ProcessException; +import org.apache.nifi.processor.io.OutputStreamCallback; +import org.apache.nifi.processor.util.StandardValidators; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.springframework.beans.factory.support.StaticListableBeanFactory; +import org.springframework.integration.mail.AbstractMailReceiver; +import org.springframework.util.Assert; +import org.springframework.util.StreamUtils; + +/** + * Base processor for implementing processors to consume messages from Email + * servers using Spring Integration libraries. + * + * @param <T> + * the type of {@link AbstractMailReceiver}. + */ +abstract class AbstractEmailProcessor<T extends AbstractMailReceiver> extends AbstractProcessor { + + public static final PropertyDescriptor HOST = new PropertyDescriptor.Builder() + .name("Host Name") + .description("Network address of Email server (e.g., pop.gmail.com, imap.gmail.com . . .)") + .required(true) + .expressionLanguageSupported(true) + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .build(); + public static final PropertyDescriptor PORT = new PropertyDescriptor.Builder() + .name("Port") + .description("Numeric value identifying Port of Email server (e.g., 993)") + .required(true) + .expressionLanguageSupported(true) + .addValidator(StandardValidators.PORT_VALIDATOR) + .build(); + public static final PropertyDescriptor USER = new PropertyDescriptor.Builder() + .name("User Name") + .description("User Name used for authentication and authorization with Email server.") + .required(true) + .expressionLanguageSupported(true) + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .build(); + public static final PropertyDescriptor PASSWORD = new PropertyDescriptor.Builder() + .name("Password") + .description("Password used for authentication and authorization with Email server.") + .required(true) + .expressionLanguageSupported(true) + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .sensitive(true) + .build(); + public static final PropertyDescriptor FOLDER = new PropertyDescriptor.Builder() + .name("Folder") + .description("Email folder to retrieve messages from (e.g., INBOX)") + .required(true) + .expressionLanguageSupported(true) + .defaultValue("INBOX") + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .build(); + public static final PropertyDescriptor FETCH_SIZE = new PropertyDescriptor.Builder() + .name("Fetch Size") + .description("Specify the maximum number of Messages to fetch per call to Email Server.") + .required(true) + .expressionLanguageSupported(true) + .defaultValue("10") + .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR) + .build(); + public static final PropertyDescriptor SHOULD_DELETE_MESSAGES = new PropertyDescriptor.Builder() + .name("Delete Messages") + .description("Specify whether mail messages should be deleted after retrieval.") + .required(true) + .allowableValues("true", "false") + .defaultValue("false") + .addValidator(StandardValidators.BOOLEAN_VALIDATOR) + .build(); + + static final Relationship REL_SUCCESS = new Relationship.Builder() + .name("success") + .description("All messages that are the are successfully received from Email server and converted to FlowFiles are routed to this relationship") + .build(); + + static List<PropertyDescriptor> SHARED_DESCRIPTORS = new ArrayList<>(); + + static Set<Relationship> SHARED_RELATIONSHIPS = new HashSet<>(); + + /* + * Will ensure that list of PropertyDescriptors is build only once, since + * all other lifecycle methods are invoked multiple times. + */ + static { + SHARED_DESCRIPTORS.add(HOST); + SHARED_DESCRIPTORS.add(PORT); + SHARED_DESCRIPTORS.add(USER); + SHARED_DESCRIPTORS.add(PASSWORD); + SHARED_DESCRIPTORS.add(FOLDER); + SHARED_DESCRIPTORS.add(FETCH_SIZE); + SHARED_DESCRIPTORS.add(SHOULD_DELETE_MESSAGES); + + SHARED_RELATIONSHIPS.add(REL_SUCCESS); + } + + protected final Logger logger = LoggerFactory.getLogger(this.getClass()); + + protected volatile T messageReceiver; + + private volatile BlockingQueue<Message> messageQueue; + + private volatile String displayUrl; + + private volatile ProcessSession processSession; + + @OnStopped + public void stop(ProcessContext processContext) { + this.flushRemainingMessages(processContext); + try { + this.messageReceiver.destroy(); + this.messageReceiver = null; + } catch (Exception e) { + this.logger.warn("Failure while closing processor", e); + } + } + + /** + * + */ + @Override + public Set<Relationship> getRelationships() { + return SHARED_RELATIONSHIPS; + } + + /** + * + */ + @Override + public void onTrigger(ProcessContext context, ProcessSession processSession) throws ProcessException { + this.initializefNecessary(context, processSession); + + Message emailMessage = this.receiveMessage(); + if (emailMessage != null) { + this.disposeMessage(emailMessage, context, processSession); + } + } + + /** + * + */ + @Override + protected PropertyDescriptor getSupportedDynamicPropertyDescriptor(final String propertyDescriptorName) { + return new PropertyDescriptor.Builder() + .description("Specifies the value for '" + propertyDescriptorName + "' Java Mail property.") + .name(propertyDescriptorName).addValidator(StandardValidators.NON_EMPTY_VALIDATOR).dynamic(true) + .build(); + } + + /** + * Delegates to sub-classes to build the target receiver as + * {@link AbstractMailReceiver} + * + * @param context + * instance of {@link ProcessContext} + * @return new instance of {@link AbstractMailReceiver} + */ + protected abstract T buildMessageReceiver(ProcessContext context); + + /** + * Return the target receivere's mail protocol (e.g., imap, pop etc.) + */ + protected abstract String getProtocol(ProcessContext processContext); + + /** + * Builds the url used to connect to the email server. + */ + String buildUrl(ProcessContext processContext) { + String host = processContext.getProperty(HOST).evaluateAttributeExpressions().getValue(); + String port = processContext.getProperty(PORT).evaluateAttributeExpressions().getValue(); + String user = processContext.getProperty(USER).evaluateAttributeExpressions().getValue(); + String password = processContext.getProperty(PASSWORD).evaluateAttributeExpressions().getValue(); + String folder = processContext.getProperty(FOLDER).evaluateAttributeExpressions().getValue(); + + StringBuilder urlBuilder = new StringBuilder(); + try { + urlBuilder.append(URLEncoder.encode(user, "UTF-8")); + } catch (UnsupportedEncodingException e) { + throw new ProcessException(e); + } + urlBuilder.append(":"); + try { + urlBuilder.append(URLEncoder.encode(password, "UTF-8")); + } catch (UnsupportedEncodingException e) { + throw new ProcessException(e); + } + urlBuilder.append("@"); + urlBuilder.append(host); + urlBuilder.append(":"); + urlBuilder.append(port); + urlBuilder.append("/"); + urlBuilder.append(folder); + + String protocol = this.getProtocol(processContext); + String finalUrl = protocol + "://" + urlBuilder.toString(); + + // build display-safe URL + int passwordStartIndex = urlBuilder.indexOf(":") + 1; + int passwordEndIndex = urlBuilder.indexOf("@"); + urlBuilder.replace(passwordStartIndex, passwordEndIndex, "[password]"); + this.displayUrl = protocol + "://" + urlBuilder.toString(); + if (this.logger.isInfoEnabled()) { + this.logger.info("Connecting to Email server at the following URL: " + this.displayUrl); + } + + return finalUrl; + } + + /** + * Builds and initializes the target message receiver if necessary (if it's + * null). Upon execution of this operation the receiver is fully functional + * and is ready to receive messages. + */ + private synchronized void initializefNecessary(ProcessContext context, ProcessSession processSession) { + if (this.messageReceiver == null) { + this.processSession = processSession; + this.messageReceiver = this.buildMessageReceiver(context); + + boolean shouldDelete = context.getProperty(SHOULD_DELETE_MESSAGES).asBoolean(); + int fetchSize = context.getProperty(FETCH_SIZE).evaluateAttributeExpressions().asInteger(); + + this.messageReceiver.setShouldDeleteMessages(shouldDelete); --- End diff -- Are you referring to the POP3 command `"DELE xxxxx"` ? If so, do not assume Trash as POP3 is notorious for lacking support of folders. Messages marked with DELE may be deleted by the server side after disconnect. Spring seems to transparently handle that [here](https://github.com/spring-projects/spring-integration/blob/master/spring-integration-mail/src/main/java/org/springframework/integration/mail/AbstractMailReceiver.java#L409): ``` private void postProcessFilteredMessages(Message[] filteredMessages) throws MessagingException { setMessageFlags(filteredMessages); if (shouldDeleteMessages()) { deleteMessages(filteredMessages); } if (this.headerMapper == null) { // Copy messages to cause an eager fetch for (int i = 0; i < filteredMessages.length; i++) { MimeMessage mimeMessage = new IntegrationMimeMessage((MimeMessage) filteredMessages[i]); filteredMessages[i] = mimeMessage; } } } ``` I am happy to test tomorrow morning but if Spring follows the traditional POP3 model it will perform a RETR followed by a DELE. That could mean the returned message exists solely within the NiFi instance retrieving it. If by any chance the processor disposeMessage method hits an issue, the message would be lost. I will double check it tomorrow morning (AEST)
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