7 Adding Container Capabilities

Example 7-1 Example Implementation of Container

This example shows a Java programming language class that implements the Container interface and is capable of extending the functionality of GlassFish Server.

package com.example.containers;
contains
@Service(name="com.example.containers.MyContainer")
public class MyContainer implements Container {
    public String getName() {
        return "MyContainer";
    }

    public Class<? extends org.glassfish.api.deployment.Deployer> getDeployer() {
        return MyDeployer.class;
    }
}

Example 7-2 Example Implementation of Deployer

package com.example.containers;

@Service
public class MyDeployer {

    public MetaData getMetaData() {
        return new MetaData(...);
    }

    public <V> v loadMetaData(Class<V> type, DeploymentContext dc) {
        ...
    }

    public boolean prepare(DeploymentContext dc) {
        // performs any actions needed to allow the application to run, 
        // such as generating artifacts
        ...
    }

    public MyApplication load(MyContainer container, DeploymentContext dc) {
        // creates a new instance of an application
        MyApplication myApp = new MyApplication (...);
        ...
        // returns the application instance
        return myApp;
    }

    public void unload(MyApplication myApp, DeploymentContext dc) {
        // stops and removes the application 
        ...
    }

    public void clean (DeploymentContext dc) {
        // cleans up any artifacts generated during prepare()
        ...
    }
}

Example 7-3 Annotation to Denote a Container's Component

This example shows the code for defining a component of the Greeter container.

package org.glassfish.examples.extension.greeter;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

/**
 * Simple annotation to denote Greeter's component
 */
@Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
public @interface Greeter {

    /**
     * Name to uniquely identify different greeters
     *
     * @return a good greeter name
     */
    public String name();
}

Example 7-4 Application Container Class

This example shows the Java language class GreeterAppContainer, which implements the ApplicationContainer interface.

package org.glassfish.examples.extension.greeter;

import org.glassfish.api.deployment.ApplicationContainer;
import org.glassfish.api.deployment.ApplicationContext;
import org.glassfish.api.deployment.archive.ReadableArchive;

import java.util.List;
import java.util.ArrayList;

public class GreeterAppContainer implements ApplicationContainer {

    final GreeterContainer ctr;
    final List<Class> componentClasses = new ArrayList<Class>();
    
    public GreeterAppContainer(GreeterContainer ctr) {
        this.ctr = ctr;
    }

    void addComponent(Class componentClass) {
        componentClasses.add(componentClass);
    }

    public Object getDescriptor() {
        return null;
    }
                       
    public boolean start(ApplicationContext startupContext) throws Exception {
        for (Class componentClass : componentClasses) {
            try {
                Object component = componentClass.newInstance();
                Greeter greeter = (Greeter) 
                     componentClass.getAnnotation(Greeter.class);
                ctr.habitat.addComponent(greeter.name(), component);
            } catch(Exception e) {
                throw new RuntimeException(e);
            }
        }
        return true;
    }

    public boolean stop(ApplicationContext stopContext) {
        for (Class componentClass : componentClasses) {
            ctr.habitat.removeAllByType(componentClass);
        }
        return true;
    }

    public boolean suspend() {
        return false;
    }

    public boolean resume() throws Exception {
        return false;
    }

    public ClassLoader getClassLoader() {
        return null;
    }
}

Example 7-5 Container Class

This example shows the Java language class GreeterContainer, which implements the Container interface.

package org.glassfish.examples.extension.greeter;

import org.glassfish.api.container.Container;
import org.glassfish.api.deployment.Deployer;
import org.jvnet.hk2.annotations.Service;
import org.jvnet.hk2.annotations.Inject;
import org.jvnet.hk2.component.Habitat;

@Service(name="org.glassfish.examples.extension.GreeterContainer")
public class GreeterContainer implements Container {

    @Inject
    Habitat habitat;

    public Class<? extends Deployer> getDeployer() {
        return GreeterDeployer.class;
    }

    public String getName() {
        return "greeter";
    }
}

Example 7-6 Deployer Class

This example shows the Java language class GreeterDeployer, which implements the Deployer interface.

package org.glassfish.examples.extension.greeter;

import org.glassfish.api.deployment.Deployer;
import org.glassfish.api.deployment.MetaData;
import org.glassfish.api.deployment.DeploymentContext;
import org.glassfish.api.deployment.ApplicationContainer;
import org.glassfish.api.deployment.archive.ReadableArchive;
import org.glassfish.api.container.Container;
import org.jvnet.hk2.annotations.Service;

import java.util.Enumeration;

@Service
public class GreeterDeployer
    implements Deployer<GreeterContainer, GreeterAppContainer> {

    public MetaData getMetaData() {
        return null;
    }

    public <V> V loadMetaData(Class<V> type, DeploymentContext context) {
        return null;
    }

    public boolean prepare(DeploymentContext context) {
        return false;
    }

    public GreeterAppContainer load(
        GreeterContainer container, DeploymentContext context) {

        GreeterAppContainer appCtr = new GreeterAppContainer(container);
        ClassLoader cl = context.getClassLoader();

        ReadableArchive ra = context.getOriginalSource();
        Enumeration<String> entries = ra.entries();
        while (entries.hasMoreElements()) {
            String entry = entries.nextElement();
            if (entry.endsWith(".class")) {
                String className = entryToClass(entry);
                try {
                    Class componentClass = cl.loadClass(className);
                    // ensure it is one of our component
                    if (componentClass.isAnnotationPresent(Greeter.class)) {
                        appCtr.addComponent(componentClass);
                    }
                } catch(Exception e) {
                    throw new RuntimeException(e);
                }

            }
        }
        return appCtr;
    }

    public void unload(GreeterAppContainer appContainer, DeploymentContext context) {

    }

    public void clean(DeploymentContext context) {

    }

    private String entryToClass(String entry) {
        String str = entry.substring("WEB-INF/classes/".length(), entry.length()-6);
        return str.replaceAll("/", ".");
    }
}

Example 7-7 Sniffer Class

This example shows the Java language class GreeterSniffer, which implements the Sniffer interface.

package org.glassfish.examples.extension.greeter;

import org.glassfish.api.container.Sniffer;
import org.glassfish.api.deployment.archive.ReadableArchive;
import org.glassfish.api.admin.config.ConfigParser;
import org.glassfish.examples.extension.greeter.config.GreeterContainerConfig;
import org.jvnet.hk2.annotations.Service;
import org.jvnet.hk2.annotations.Inject;
import org.jvnet.hk2.component.Habitat;
import com.sun.enterprise.module.Module;

import java.util.logging.Logger;
import java.util.Map;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Array;
import java.net.URL;

/**
 * @author Jerome Dochez
 */
@Service(name="greeter")
public class GreeterSniffer implements Sniffer {

    @Inject(optional=true)
    GreeterContainerConfig config=null;

    @Inject
    ConfigParser configParser;

    @Inject
    Habitat habitat;

    public boolean handles(ReadableArchive source, ClassLoader loader) {
        return false;
    }

    public String[] getURLPatterns() {
        return new String[0];
    }

    public Class<? extends Annotation>[] getAnnotationTypes() {
        Class<? extends Annotation>[] a = (Class<? extends Annotation>[]) Array.newInstance(Class.class, 1);
        a[0] = Greeter.class;
        return a;
    }

    public String getModuleType() {
        return "greeter";
    }

    public Module[] setup(String containerHome, Logger logger) throws IOException {
        if (config==null) {
            URL url = this.getClass().getClassLoader().getResource("init.xml");
            if (url!=null) {
                configParser.parseContainerConfig(
                    habitat, url, GreeterContainerConfig.class);
            }
        }
        return null;
    }

    public void tearDown() {

    }

    public String[] getContainersNames() {
        String[] c = { GreeterContainer.class.getName() };
        return c;
    }

    public boolean isUserVisible() {
        return true;
    }

    public Map<String, String> getDeploymentConfigurations
        (ReadableArchive source) throws IOException {
        return null;
    }

    public String[] getIncompatibleSnifferTypes() {
        return new String[0];
    }
}

Example 7-8 Container Client Class

import components.SimpleGreeter;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.annotation.WebServlet; 
import javax.servlet.*;
import javax.servlet.http.*;
import javax.annotation.Resource;


@WebServlet(urlPatterns={"/hello"})
public class HelloWorld extends HttpServlet {

    @Resource(name="Simple")
    SimpleGreeter greeter;
  
    public void doGet(HttpServletRequest req, HttpServletResponse res)
            throws IOException, ServletException {

        
        PrintWriter pw = res.getWriter();
        try {
            pw.println("Injected service is " + greeter);
            if (greeter!=null) {
                pw.println("SimpleService says " + greeter.saySomething());
                pw.println("<br>");
            }
                } catch(Exception e) {
                e.printStackTrace();
        }
    }
}

Example 7-9 Component for Container Client

package components;

import org.glassfish.examples.extension.greeter.Greeter;

@Greeter(name="simple")
public class SimpleGreeter {

    public String saySomething() {
        return "Bonjour";
    }
}

Example 7-10 Deployment Descriptor for Container Client

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
  xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/ Line break added for readability
xml/ns/javaee/web-app_2_5.xsd">
</web-app>