Github user brosander commented on a diff in the pull request: https://github.com/apache/nifi/pull/525#discussion_r68795669 --- Diff: nifi-nar-bundles/nifi-windows-event-log-bundle/nifi-windows-event-log-processors/src/main/java/org/apache/nifi/processors/windows/event/log/ConsumeWindowsEventLog.java --- @@ -0,0 +1,282 @@ +/* + * 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.windows.event.log; + +import com.sun.jna.platform.win32.Kernel32; +import com.sun.jna.platform.win32.Kernel32Util; +import com.sun.jna.platform.win32.WinNT; +import org.apache.commons.io.Charsets; +import org.apache.nifi.annotation.behavior.InputRequirement; +import org.apache.nifi.annotation.behavior.TriggerSerially; +import org.apache.nifi.annotation.behavior.WritesAttribute; +import org.apache.nifi.annotation.behavior.WritesAttributes; +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.flowfile.FlowFile; +import org.apache.nifi.flowfile.attributes.CoreAttributes; +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.processor.util.StandardValidators; +import org.apache.nifi.processors.windows.event.log.jna.ErrorLookup; +import org.apache.nifi.processors.windows.event.log.jna.EventSubscribeXmlRenderingCallback; +import org.apache.nifi.processors.windows.event.log.jna.WEvtApi; + +import java.net.URI; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collection; +import java.util.Collections; +import java.util.HashSet; +import java.util.List; +import java.util.Set; +import java.util.concurrent.BlockingQueue; +import java.util.concurrent.LinkedBlockingQueue; + + +@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN) +@Tags({"ingest", "event", "windows"}) +@TriggerSerially +@CapabilityDescription("Registers a Windows Event Log Subscribe Callback to receive FlowFiles from Events on Windows. These can be filtered via channel and XPath.") +@WritesAttributes({ + @WritesAttribute(attribute = "mime.type", description = "Will set a MIME type value of application/xml.") +}) +public class ConsumeWindowsEventLog extends AbstractSessionFactoryProcessor { + public static final String DEFAULT_CHANNEL = "System"; + public static final String DEFAULT_XPATH = "*"; + public static final int DEFAULT_MAX_BUFFER = 1024 * 1024; + public static final int DEFAULT_MAX_QUEUE_SIZE = 1024; + + public static final PropertyDescriptor CHANNEL = new PropertyDescriptor.Builder() + .name("channel") + .displayName("Channel") + .required(true) + .defaultValue(DEFAULT_CHANNEL) + .description("The Windows Event Log Channel to listen to.") + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .build(); + + public static final PropertyDescriptor QUERY = new PropertyDescriptor.Builder() + .name("query") + .displayName("XPath Query") + .required(true) + .defaultValue(DEFAULT_XPATH) + .description("XPath Query to filter events. (See https://msdn.microsoft.com/en-us/library/windows/desktop/dd996910(v=vs.85).aspx for examples.)") + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .build(); + + public static final PropertyDescriptor MAX_BUFFER_SIZE = new PropertyDescriptor.Builder() + .name("maxBuffer") + .displayName("Maximum Buffer Size") + .required(true) + .defaultValue(Integer.toString(DEFAULT_MAX_BUFFER)) + .description("The individual Event Log XMLs are rendered to a buffer." + + " This specifies the maximum size in bytes that the buffer will be allowed to grow to. (Limiting the maximum size of an individual Event XML.)") + .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR) + .build(); + + public static final PropertyDescriptor MAX_EVENT_QUEUE_SIZE = new PropertyDescriptor.Builder() + .name("maxQueue") + .displayName("Maximum queue size") + .required(true) + .defaultValue(Integer.toString(DEFAULT_MAX_QUEUE_SIZE)) + .description("Maximum number of events to queue for transformation into FlowFiles.") + .addValidator(StandardValidators.POSITIVE_INTEGER_VALIDATOR) + .build(); + + public static final List<PropertyDescriptor> PROPERTY_DESCRIPTORS = Collections.unmodifiableList(Arrays.asList(CHANNEL, QUERY, MAX_BUFFER_SIZE, MAX_EVENT_QUEUE_SIZE)); + + public static final Relationship REL_SUCCESS = new Relationship.Builder() + .name("success") + .description("Relationship for successfully consumed events.") + .build(); + + public static final Set<Relationship> RELATIONSHIPS = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(REL_SUCCESS))); + public static final String APPLICATION_XML = "application/xml"; + private final WEvtApi wEvtApi; + private final Kernel32 kernel32; + private final ErrorLookup errorLookup; + private final String name; + + private Throwable wEvtApiError = null; + private Throwable kernel32Error = null; + + private BlockingQueue<String> renderedXMLs; + private WEvtApi.EVT_SUBSCRIBE_CALLBACK evtSubscribeCallback; + private WinNT.HANDLE subscriptionHandle; + private ProcessSessionFactory sessionFactory; + private String provenanceUri; + + /** + * Framework constructor + */ + public ConsumeWindowsEventLog() { + this(null, null); + } + + /** + * Constructor that allows injection of JNA interfaces + * + * @param wEvtApi event api interface + * @param kernel32 kernel interface + */ + public ConsumeWindowsEventLog(WEvtApi wEvtApi, Kernel32 kernel32) { + this.wEvtApi = wEvtApi == null ? loadWEvtApi() : wEvtApi; + this.kernel32 = kernel32 == null ? loadKernel32() : kernel32; + this.errorLookup = new ErrorLookup(this.kernel32); + if (kernel32 != null) { + name = Kernel32Util.getComputerName(); + } else { + // Won't be able to use the processor anyway because native libraries didn't load + name = null; + } + } + + private WEvtApi loadWEvtApi() { + try { + return WEvtApi.INSTANCE; + } catch (Throwable e) { + wEvtApiError = e; + return null; + } + } + + private Kernel32 loadKernel32() { + try { + return Kernel32.INSTANCE; + } catch (Throwable e) { + kernel32Error = e; + return null; + } + } + + /** + * Register subscriber via native call + * + * @param context the process context + */ + @OnScheduled + public void onScheduled(ProcessContext context) throws Exception { + String channel = context.getProperty(CHANNEL).getValue(); + String query = context.getProperty(QUERY).getValue(); + + renderedXMLs = new LinkedBlockingQueue<>(context.getProperty(MAX_EVENT_QUEUE_SIZE).asInteger()); + provenanceUri = new URI("winlog", name, "/" + channel, query, null).toASCIIString(); + + evtSubscribeCallback = new EventSubscribeXmlRenderingCallback(getLogger(), s -> { + try { + renderedXMLs.put(s); + } catch (InterruptedException e) { + throw new IllegalStateException("Got interrupted while waiting to add to queue.", e); + } + }, context.getProperty(MAX_BUFFER_SIZE).asInteger(), wEvtApi, kernel32, errorLookup); + + subscriptionHandle = wEvtApi.EvtSubscribe(null, null, channel, query, null, null, + evtSubscribeCallback, WEvtApi.EvtSubscribeFlags.SUBSCRIBE_TO_FUTURE); + if (subscriptionHandle == null || subscriptionHandle.getPointer() == null) { + throw new Exception("Unable to subscribe with provided parameters, received the following error code: " + + errorLookup.getLastError()); + } + } + + /** + * Cleanup + */ + @OnStopped + public void stop() { + wEvtApi.EvtClose(subscriptionHandle); + subscriptionHandle = null; + evtSubscribeCallback = null; + if (!renderedXMLs.isEmpty()) { + if (sessionFactory != null) { + getLogger().info("Finishing processing leftover events"); + ProcessSession session = sessionFactory.createSession(); + processQueue(session); + } else { + throw new ProcessException("Stopping the processor but there is no ProcessSessionFactory stored and there are messages in the internal queue. Removing the processor now will " + + "clear the queue but will result in DATA LOSS. This is normally due to starting the processor, receiving events and stopping before the onTrigger happens. The messages " + + "in the internal queue cannot finish processing until until the processor is triggered to run."); + } + } + sessionFactory = null; + provenanceUri = null; + renderedXMLs = null; + } + + @Override + public void onTrigger(ProcessContext context, ProcessSessionFactory sessionFactory) throws ProcessException { + this.sessionFactory = sessionFactory; + processQueue(sessionFactory.createSession()); + } + + private void processQueue(ProcessSession session) { + String xml; + while ((xml = renderedXMLs.peek()) != null) { + FlowFile flowFile = session.create(); + byte[] xmlBytes = xml.getBytes(Charsets.UTF_8); --- End diff -- Here we have a java string (charset agnostic) which we are asking for bytes in UTF_8 to write to the flowfile. I was just trying to make the contents of the flowfile not depend on java implementation by explicitly getting bytes in UTF_8.
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