[GitHub] [nifi] ijokarumawak commented on a change in pull request #3344: NIFI-6092 Create ListenSlack and FetchSlack processors

[GitBox <gi...@apache.org>]

ijokarumawak commented on a change in pull request #3344: NIFI-6092 Create ListenSlack and FetchSlack processors
URL: https://github.com/apache/nifi/pull/3344#discussion_r265403103
 
 

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 File path: nifi-nar-bundles/nifi-slack-bundle/nifi-slack-processors/src/main/java/org/apache/nifi/processors/slack/ListenSlack.java
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+/*
+ * 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.slack;
+
+import java.io.StringReader;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
+
+import javax.json.Json;
+import javax.json.JsonException;
+import javax.json.JsonReader;
+
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+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.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.annotation.lifecycle.OnShutdown;
+import org.apache.nifi.annotation.lifecycle.OnUnscheduled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.Validator;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.AbstractSessionFactoryProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.ProcessSessionFactory;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processors.slack.controllers.SlackConnectionService;
+
+@Tags({"slack", "listen", "json", "events"})
+@CapabilityDescription("Listens on the provided slack connection controller service and " +
+  "forwards the messages in JSON text format.")
+@SeeAlso({SlackConnectionService.class, FetchSlack.class})
+@InputRequirement(Requirement.INPUT_FORBIDDEN)
+public class ListenSlack extends AbstractSessionFactoryProcessor {
+
+  private volatile ProcessSessionFactory processSessionFactory;
+
+  private volatile SlackConnectionService slackConnectionService;
+
+  private volatile List<String> matchingTypes;
+
+  private volatile boolean matchAny;
+
+  static final PropertyDescriptor SLACK_CONNECTION_SERVICE = new PropertyDescriptor.Builder()
+    .name("slack-connection-service")
+    .displayName("Slack Connection ControllerService")
+    .description("A ControllerService that provides a connection to slack service.")
+    .required(true)
+    .identifiesControllerService(SlackConnectionService.class)
+    .build();
+
+  static final PropertyDescriptor MESSAGE_TYPES = new PropertyDescriptor
+    .Builder()
+    .name("message-types")
+    .displayName("Message types")
+    .description("Message types to listen to. It will filter messages with the given types or " +
+      "listen to every type if empty. It is a coma separated list like: message,file_shared")
+    .required(false)
+    .addValidator(Validator.VALID)
+    .build();
+
+  static final Relationship MATCHED_MESSAGES_RELATIONSHIP = new Relationship.Builder()
+    .name("matched")
+    .description("Incoming messages that matches the given types")
+    .build();
+
+  static final Relationship UNMATCHED_MESSAGES_RELATIONSHIP = new Relationship.Builder()
+    .name("unmatched")
+    .description("Incoming messages that does not match the given types")
+    .autoTerminateDefault(true)
+    .build();
+
+  private static final String JSON_OBJECT_TYPE_KEY = "type";
+
+  private static final List<PropertyDescriptor> DESCRIPTORS = Collections.unmodifiableList(Arrays.asList(
+    SLACK_CONNECTION_SERVICE, MESSAGE_TYPES));
+
+  private static final Set<Relationship> RELATIONSHIPS = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
+    MATCHED_MESSAGES_RELATIONSHIP, UNMATCHED_MESSAGES_RELATIONSHIP)));
+
+  @Override
+  public Set<Relationship> getRelationships() {
+    return RELATIONSHIPS;
+  }
+
+  @Override
+  public final List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+    return DESCRIPTORS;
+  }
+
+  @OnScheduled
+  public void onScheduled(final ProcessContext context) {
+    String messageTypes = context.getProperty(MESSAGE_TYPES).getValue();
+    messageTypes = messageTypes == null ? "" : messageTypes;
+    matchAny = messageTypes.isEmpty();
+    matchingTypes = Arrays.asList(messageTypes.split(","));
+  }
+
+  @OnUnscheduled
+  @OnShutdown
+  public void onUnscheduled() {
+    if (isProcessorRegisteredToService()) {
+      deregister();
+    }
+  }
+
+  private void deregister() {
+    slackConnectionService.deregisterProcessor(this);
+  }
+
+  @Override
+  public void onTrigger(ProcessContext context, ProcessSessionFactory sessionFactory) throws ProcessException {
+    if (processSessionFactory == null) {
+      processSessionFactory = sessionFactory;
+    }
+    if (!isProcessorRegisteredToService()) {
+      registerProcessorToService(context);
+    }
+    context.yield();
+  }
+
+  private boolean isProcessorRegisteredToService() {
+    return slackConnectionService != null
+      && slackConnectionService.isProcessorRegistered(this);
+  }
+
+  private void registerProcessorToService(ProcessContext context) {
+      try {
+        slackConnectionService = context.getProperty(SLACK_CONNECTION_SERVICE)
+          .asControllerService(SlackConnectionService.class);
+        slackConnectionService.registerProcessor(this, getMessageHandler(processSessionFactory));
+      } catch (Exception e) {
+        getLogger().error("Error while creating slack client", e);
+        slackConnectionService.deregisterProcessor(this);
+        context.yield();
+      }
+  }
+
+  private Consumer<String> getMessageHandler(ProcessSessionFactory sessionFactory) {
+    return message -> {
+      ProcessSession session = sessionFactory.createSession();
+      try {
+        FlowFile flowFile = session.create();
+        session.write(flowFile, outputStream -> outputStream.write(message.getBytes()));
+        session.getProvenanceReporter().receive(flowFile, "slack");
+
+        if (matches(message)) {
+          session.transfer(flowFile, MATCHED_MESSAGES_RELATIONSHIP);
 
 Review comment:
   Usually, Listen/Consume processors only have 'success' relationship. I suggest following that convention. Only create a FlowFile when the message matches. Then transfer it to 'success' relationship.
   
   Even if we have matched/unmatched relationship, I imagine most use-cases auto terminate 'unmatched'.

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