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

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"/>

ServiceLoaderorg.jboss.as.controller.Extension

org.wildfly.extension.sdd.SDDExtension

WRITE SIMPLE EXTENSION

Building blocks

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

Extension class

public class SDDExtension implements Extension {@Overridepublic void initializeParsers(ExtensionParsingContext context) {

}

@Overridepublic void initialize(ExtensionContext context) {

}}

Service Loader entry

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

Define root modelpublic class SDDRootResource extends PersistentResourceDefinition {

static final SDDRootResource INSTANCE = new SDDRootResource();

private SDDRootResource() {super(SDDExtension.SUBSYSTEM_PATH,

SDDExtension.getResolver(),new SDDSubsystemAdd(),ReloadRequiredRemoveStepHandler.INSTANCE);

}

@Overridepublic void registerOperations(ManagementResourceRegistration resourceRegistration) {

super.registerOperations(resourceRegistration); resourceRegistration.registerOperationHandler(GenericSubsystemDescribeHandler.DEFINITION, GenericSubsystemDescribeHandler.INSTANCE, false);

}}

Define root add handler

public class SDDSubsystemAdd extends AbstractBoottimeAddStepHandler {

@Overrideprotected void populateModel(ModelNode operation, ModelNode model) throws OperationFailedException

{model.setEmptyObject();

}

Define namespace

enum Namespace {

// must be firstUNKNOWN(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 parserclass SDDSubsystemParser implements XMLStreamConstants, XMLElementReader<List<ModelNode>> {

static final PersistentResourceXMLDescription xmlDescription = builder(SDDRootResource.INSTANCE).build();

@Overridepublic 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);}

@Overridepublic 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());

}

@Overrideprotected String getSubsystemXml() throws IOException {

return readResource("sdd-1.0.xml");}

}

SILLY DEPLOYMENT DETECTOR

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 definitionclass 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);

}

@Overridepublic 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

Demo

• https://github.com/ctomc/wildfly-sdd

• https://github.com/wildfly/wildfly

• http://www.wildfly.org/

Questions?