Extending WildFly

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Information about Extending WildFly

Published on February 17, 2014

Author: JBUG_London

Source: slideshare.net


Presentation by Tomaz Cerar (Red Hat), delivered at the London JBoss User Group event on the 12th of February 2014.
Watch the video here: http://www.youtube.com/watch?v=eu9K5NLUKBI
Join London JBUG: http://www.c2b2.co.uk/jbug

Extending WildFly Tomaž Cerar, Red Hat

Agenda • • • • • What are extensions WildFly core Write simple extension Silly deployment detector Demo

What are extensions? • Entry point for extending WildFly • Can provide – new deployment types – new model – services – resources


WildFly core • Really small (< 15 mb) • Consists of – JBoss Modules – Modular Service Controller (MSC) – Domain management (CLI, rest) – Deployment manager – Logging

JBoss Modules • Modular class loader • Isolated class loader • Can be a set of many resources (jars)

Domain management • Manages configuration • Backbone for all extensions • Accessible via – Extensions – CLI – Admin console – DMR clients –…

MSC • • • • Truly concurrent service container Handles service dependencies Handles lifecycle “real” functionality should be in services

DMR • • • • Detyped Model Representation JSON like Internal format for all operations Internal model (ModelNode)

Domain model definition • Attributes • Resources • Resource tree – PathElement – Single target (key=value) – Multi target (key=*) • Resolvers & multi language support

Operation handlers • Defines operations on resources • Execution stage – MODEL – RUNTIME – VERIFY – DOMAIN – DONE • Can be chained

Resource handlers • Every resource needs add & remove • In MODEL phase – validate and set model • In RUNTIME phase – Add services – Add deployment processors

Deployment manager • Deployment repository • Defines deployment phases • Provides deployment processor infrastructure • Can be used via – Domain management – Deployment scanner

Deployment processor • Hooks into deployment lifecycle • Can modify deployment behavior • Can define new deployment type

Extension point • • • • • Loaded via Service Loader Can define many subsystems Packaged as JBoss Module Referenced in configuration Can provide any new functionality

Extension loading standalone.xml <extension module="org.wildfly.extension.sdd"/> ServiceLoader org.jboss.as.controller.Extension org.wildfly.extension.sdd.SDDExtension


Building blocks • • • • • Define Extension point Define Root Model Define Add handler Define XML parser Define XML marshaller

Extension class public class SDDExtension implements Extension { @Override public void initializeParsers(ExtensionParsingContext context) { } @Override public void initialize(ExtensionContext context) { } }

Service Loader entry • Point it to implementation class – org.wildfly.extension.sdd.SDDExtension

Define root model public class SDDRootResource extends PersistentResourceDefinition { static final SDDRootResource INSTANCE = new SDDRootResource(); private SDDRootResource() { super(SDDExtension.SUBSYSTEM_PATH, SDDExtension.getResolver(), new SDDSubsystemAdd(), ReloadRequiredRemoveStepHandler.INSTANCE); } @Override public void registerOperations(ManagementResourceRegistration resourceRegistration) { super.registerOperations(resourceRegistration); resourceRegistration.registerOperationHandler(GenericSubsystemDescribeHandler.DEFINITION, GenericSubsystemDescribeHandler.INSTANCE, false); } }

Define root add handler public class SDDSubsystemAdd extends AbstractBoottimeAddStepHandler { { @Override protected void populateModel(ModelNode operation, ModelNode model) throws OperationFailedException } model.setEmptyObject();

Define namespace enum Namespace { // must be first UNKNOWN(null), SDD_1_0("urn:wildfly:domain:sdd:1.0"); /** * The current namespace version. */ public static final Namespace CURRENT = SDD_1_0; private final String name; } Namespace(final String name) { this.name = name; }

Define XML model <subsystem xmlns="urn:wildfly:domain:sdd:1.0"/>

Define parser class SDDSubsystemParser implements XMLStreamConstants, XMLElementReader<List<ModelNode>> { static final PersistentResourceXMLDescription xmlDescription = builder(SDDRootResource.INSTANCE).build(); @Override public void readElement(XMLExtendedStreamReader reader, List<ModelNode> list) throws XMLStreamException { xmlDescription.parse(reader, PathAddress.EMPTY_ADDRESS, list); } }

Define marshaller public void writeContent(XMLExtendedStreamWriter writer, SubsystemMarshallingContext context) throws XMLStreamException { } context.startSubsystemElement(Namespace.CURRENT.getUriString(), false); writer.writeEndElement();

Making it all work @Override public void initializeParsers(ExtensionParsingContext context) { context.setSubsystemXmlMapping(SUBSYSTEM_NAME, Namespace.SDD_1_0.getUriString(), SDDSubsystemParser.INSTANCE); } @Override public void initialize(ExtensionContext context) { final SubsystemRegistration subsystem = context.registerSubsystem(SUBSYSTEM_NAME, 1, 0, 0); final ManagementResourceRegistration registration = subsystem.registerSubsystemModel(SDDRootResource.INSTANCE); } subsystem.registerXMLElementWriter(SDDSubsystemParser.INSTANCE);

Module definition <module xmlns="urn:jboss:module:1.1" name="org.wildfly.extension.sdd"> <resources> <resource-root path="wildfly-sdd-1.0.0.Alpha1-SNAPSHOT.jar"/> </resources> <dependencies> <module name="javax.annotation.api"/> <module name="javax.api"/> <module name="org.jboss.jandex"/> <module name="org.jboss.staxmapper"/> <module name="org.jboss.as.controller"/> <module name="org.jboss.as.server"/> <module name="org.jboss.modules"/> <module name="org.jboss.msc"/> <module name="org.jboss.vfs"/> <module name="org.jboss.logging"/> </dependencies> </module>

Module layout

What does it do? Nothing!

How to test it? • Test harness enables you to test – xml parser – model consistency – MSC services – Compatibility (transformers) – Localization resources –…

public class SDDSubsystemTestCase extends AbstractSubsystemBaseTest { public SDDSubsystemTestCase() { super(SDDExtension.SUBSYSTEM_NAME, new SDDExtension()); } } @Override protected String getSubsystemXml() throws IOException { return readResource("sdd-1.0.xml"); }


Let’s have subsystem that will detect common problems in deployments.

Silly deployment detector • Idea come from forums • Should be able to detect – Redundant JARs – Blacklisted jars – Bundling provided classes/packages – Common xml misconfigurations –…

Black listed jar detector • You configure blacklisted jar names • Subsystem warns you if they are found

What we need • Domain model • XML parser to handle new model • Deployment processor

Model definition class JarBlackListResourceDefinition extends SimpleResourceDefinition { static final JarBlackListResourceDefinition INSTANCE = new JarBlackListResourceDefinition(); private static final StringListAttributeDefinition JAR_NAMES = new StringListAttributeDefinition.Builder("jar-names") .setAllowNull(false) .setXmlName("jars") .build(); private JarBlackListResourceDefinition() { super(SDDExtension.JAR_BLACKLIST_PATH, SDDExtension.getResolver(), new JarBlackListAdd(), ReloadRequiredRemoveStepHandler.INSTANCE); } @Override public void registerAttributes(ManagementResourceRegistration resourceRegistration) { resourceRegistration.registerReadWriteAttribute(JAR_NAMES, null, new ReloadRequiredWriteAttributeHandler(JAR_NAMES)); }

XML <subsystem xmlns="urn:wildfly:domain:sdd:1.0"> <blacklist jars="mail-*.jar,activation*.jar,javassist-*.jar,jgroups-*.jar,jboss-logging-*.jar"/> </subsystem>

Deployment processor • Needs to check all jars in deployment • Compare them with blacklist


• https://github.com/ctomc/wildfly-sdd • https://github.com/wildfly/wildfly • http://www.wildfly.org/


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