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https://issues.apache.org/jira/browse/METRON-777?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16124295#comment-16124295
]
ASF GitHub Bot commented on METRON-777:
---------------------------------------
Github user mattf-horton commented on a diff in the pull request:
https://github.com/apache/metron/pull/530#discussion_r132801955
--- Diff:
bundles-lib/src/main/java/org/apache/metron/bundles/VFSBundleClassLoader.java
---
@@ -0,0 +1,515 @@
+/*
+ * 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.metron.bundles;
+
+import java.io.IOException;
+import java.net.URL;
+import java.security.CodeSource;
+import java.security.Permission;
+import java.security.PermissionCollection;
+import java.security.Permissions;
+import java.security.SecureClassLoader;
+import java.security.cert.Certificate;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.Iterator;
+import java.util.List;
+import java.util.jar.Attributes;
+import java.util.jar.Attributes.Name;
+import org.apache.commons.vfs2.FileObject;
+import org.apache.commons.vfs2.FileSystemException;
+import org.apache.commons.vfs2.FileSystemManager;
+import org.apache.commons.vfs2.NameScope;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * <p>
+ * A <tt>ClassLoader</tt> for loading BUNDLES (plugin archives). BUNDLEs
are designed to
+ * allow isolating bundles of code (comprising one-or-more
+ * plugin classes and their
+ * dependencies) from other such bundles; this allows for dependencies and
+ * processors that require conflicting, incompatible versions of the same
+ * dependency to run in a single instance of a given process.</p>
+ *
+ * <p>
+ * <tt>BundleClassLoader</tt> follows the delegation model described in
+ * {@link ClassLoader#findClass(java.lang.String)
ClassLoader.findClass(...)};
+ * classes are first loaded from the parent <tt>ClassLoader</tt>, and only
if
+ * they cannot be found there does the <tt>BundleClassLoader</tt> provide a
+ * definition. Specifically, this means that resources are loaded from the
application's
+ * <tt>conf</tt>
+ * and <tt>lib</tt> directories first, and if they cannot be found there,
are
+ * loaded from the BUNDLE.</p>
+ *
+ * <p>
+ * The packaging of a BUNDLE is such that it is a ZIP file with the
following
+ * directory structure:
+ *
+ * <pre>
+ * +META-INF/
+ * +-- bundled-dependencies/
+ * +-- <JAR files>
+ * +-- MANIFEST.MF
+ * </pre>
+ * </p>
+ *
+ * <p>
+ * The MANIFEST.MF file contains the same information as a typical JAR
file but
+ * also includes two additional bundle properties: {@code Bundle-Id} and
+ * {@code Bundle-Dependency-Id}.
+ * </p>
+ *
+ * <p>
+ * The {@code Bundle-Id} provides a unique identifier for this BUNDLE.
+ * </p>
+ *
+ * <p>
+ * The {@code Bundle-Dependency-Id} is optional. If provided, it indicates
that
+ * this BUNDLE should inherit all of the dependencies of the BUNDLE with
the provided
+ * ID. Often times, the BUNDLE that is depended upon is referred to as the
Parent.
+ * This is because its ClassLoader will be the parent ClassLoader of the
+ * dependent BUNDLE.
+ * </p>
+ *
+ * <p>
+ * If a BUNDLE is built using the Bundles Maven Plugin, the {@code
Bundle-Id} property
+ * will be set to the artifactId of the BUNDLE. The {@code
Bundle-Dependency-Id} will
+ * be set to the artifactId of the BUNDLE that is depended upon. For
example, if
+ * BUNDLE A is defined as such:
+ *
+ * <pre>
+ * ...
+ * <artifactId>bundle-a</artifactId>
+ * <packaging>bundle</packaging>
+ * ...
+ * <dependencies>
+ * <dependency>
+ * <groupId>group</groupId>
+ * <artifactId>bundle-z</artifactId>
+ * <b><type>bundle</type></b>
+ * </dependency>
+ * </dependencies>
+ * </pre>
+ * </p>
+ *
+ *
+ * <p>
+ * Then the MANIFEST.MF file that is created for Bundle A will have the
following
+ * properties set:
+ * <ul>
+ * <li>{@code {Foo}-Id: bundle-a}</li>
+ * <li>{@code {Foo}-Dependency-Id: bundle-z}</li>
+ * </ul>
+ * Where is configurable by BundleProperty META_ID_PREFIX [ default Bundle
]
+ * </p>
+ *
+ * <p>
+ * Note, above, that the {@code type} of the dependency is set to {@code
foo}.
+ * </p>
+ *
+ * <p>
+ * If the Bundle has more than one dependency of {@code type} {@code Foo},
then the
+ * Maven Bundle plugin will fail to build the Bundle.
+ * </p>
+ *
+ * This classloader is Metron Bundle aware, in that it understands that
the passed in root
+ * FileObjects may be Bundles,
+ * This class is adapted from Apache Commons VFS
+ * VFSClassLoader class v.2.1
+ * And the Apache Nifi NarClassLoader v. 1.2
+ *
+ * @see FileSystemManager#createFileSystem
+ */
+public class VFSBundleClassLoader extends SecureClassLoader {
--- End diff --
Nice job on the below.
> Create a plugin system for Metron based on 'NAR'
> ------------------------------------------------
>
> Key: METRON-777
> URL: https://issues.apache.org/jira/browse/METRON-777
> Project: Metron
> Issue Type: New Feature
> Reporter: Otto Fowler
> Assignee: Otto Fowler
>
> The success of the Metron project will be greatly dependent on community
> participation, and with that the ability to adapt and extend Metron without
> having to maintain a fork of the project.
> As organizations and individuals look to extend the Metron system with custom
> parsers, enrichments, and stellar functions that may be proprietary in
> nature, the ability to develop and deploy these extensions outside the Metron
> code base is critically important.
> To that end, and after community discussion and proposal we create or
> formalize the 'plugin' development story in Metron.
> The proposal is to adapt the Apache Nifi NAR system for use in Metron. This
> will provide the system with:
> * archetype(s) for developer projects and independent development
> * defined packaging and metadata for 'plugin' products
> * loading and instantiation with classloader isolation capabilities
> * removing the necessity for shading plugin jars
> These capabilities will also enable other features, such as plugin lifecycle,
> plugin configuration+redeployment, and other things.
> The plugin archetypes and their installation will be a followon
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