repositorystartupservlet.java

jsr170接口的java实现。是个apache的开源项目。

/*
 * 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.jackrabbit.j2ee;

import org.apache.jackrabbit.api.JackrabbitRepository;
import org.apache.jackrabbit.core.RepositoryImpl;
import org.apache.jackrabbit.core.config.RepositoryConfig;
import org.apache.jackrabbit.rmi.server.ServerAdapterFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xml.sax.InputSource;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.UnknownHostException;
import java.rmi.AlreadyBoundException;
import java.rmi.Naming;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.RMIServerSocketFactory;
import java.util.Properties;

import javax.jcr.Repository;
import javax.jcr.RepositoryException;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * The RepositoryStartupServlet starts a jackrabbit repository and registers it
 * to the JNDI environment and optional to the RMI registry.
 * <p id="registerAlgo">
 * <b>Registration with RMI</b>
 * <p/>
 * Upon successfull creation of the repository in the {@link #init()} method,
 * the repository is registered with an RMI registry if the web application is
 * so configured. To register with RMI, the following web application
 * <code>init-params</code> are considered: <code>rmi-port</code> designating
 * the port on which the RMI registry is listening, <code>rmi-host</code>
 * designating the interface on the local host on which the RMI registry is
 * active, <code>repository-name</code> designating the name to which the
 * repository is to be bound in the registry, and <code>rmi-uri</code>
 * designating an RMI URI complete with host, optional port and name to which
 * the object is bound.
 * <p/>
 * If the <code>rmi-uri</code> parameter is configured with a non-empty value,
 * the <code>rmi-port</code> and <code>rmi-host</code> parameters are ignored.
 * The <code>repository-name</code> parameter is only considered if a non-empty
 * <code>rmi-uri</code> parameter is configured if the latter does not contain
 * a name to which to bind the repository.
 * <p/>
 * This is the algorithm used to find out the host, port and name for RMI
 * registration:
 * <ol>
 * <li>If neither a <code>rmi-uri</code> nor a <code>rmi-host</code> nor a
 * <code>rmi-port</code> parameter is configured, the repository is not
 * registered with any RMI registry.
 * <li>If a non-empty <code>rmi-uri</code> parameter is configured extract the
 * host name (or IP address), port number and name to bind to from the
 * URI. If the URI is not valid, host defaults to <code>0.0.0.0</code>
 * meaning all interfaces on the local host, port defaults to the RMI
 * default port (<code>1099</code>) and the name defaults to the value
 * of the <code>repository-name</code> parameter.
 * <li>If a non-empty <code>rmi-uri</code> is not configured, the host is taken
 * from the <code>rmi-host</code> parameter, the port from the
 * <code>rmi-port</code> parameter and the name to bind the repository to
 * from the <code>repository-name</code> parameter. If the
 * <code>rmi-host</code> parameter is empty or not configured, the host
 * defaults to <code>0.0.0.0</code> meaning all interfaces on the local
 * host. If the <code>rmi-port</code> parameter is empty, not configured,
 * zero or a negative value, the default port for the RMI registry
 * (<code>1099</code>) is used.
 * </ol>
 * <p/>
 * After finding the host and port of the registry, the RMI registry itself
 * is acquired. It is assumed, that host and port primarily designate an RMI
 * registry, which should be active on the local host but has not been started
 * yet. In this case, the <code>LocateRegistry.createRegistry</code> method is
 * called to create a registry on the local host listening on the host and port
 * configured. If creation fails, the <code>LocateRegistry.getRegistry</code>
 * method is called to get a remote instance of the registry. Note, that
 * <code>getRegistry</code> does not create an actual registry on the given
 * host/port nor does it check, whether an RMI registry is active.
 * <p/>
 * When the registry has been retrieved, either by creation or by just creating
 * a remote instance, the repository is bound to the configured name in the
 * registry.
 * <p/>
 * Possible causes for registration failures include:
 * <ul>
 * <li>The web application is not configured to register with an RMI registry at
 * all.
 * <li>The registry is expected to be running on a remote host but does not.
 * <li>The registry is expected to be running on the local host but cannot be
 * accessed. Reasons include another application which does not act as an
 * RMI registry is running on the configured port and thus blocks creation
 * of a new RMI registry.
 * <li>An object may already be bound to the same name as is configured to be
 * used for the repository.
 * </ul>
 * <p/>
 * <b>Note:</b> if a <code>bootstrap-config</code> init parameter is specified the
 * servlet tries to read the respective resource, either as context resource or
 * as file. The properties specified in this file override the init params
 * specified in the <code>web.xml</code>.
 * <p/>
 * <p/>
 * <b>Setup Wizard Functionality</b><br>
 * When using the first time, the configuraition can miss the relevant
 * repository parameters in the web.xml. if so, it must contain a
 * <code>bootstrap-config</code> parameter that referrs to a propertiy file.
 * This file must exsit for proper working. If not, the repository is not
 * started.<br>
 * If the servlet is not configured correctly and accessed via http, it will
 * provide a simple wizard for the first time configuration. It propmpts for
 * a new (or existing) repository home and will copy the templates of the
 * repository.xml and bootstrap.properties to the respective location.
 */
public class RepositoryStartupServlet extends HttpServlet {

    /**
     * the default logger
     */
    private static final Logger log = LoggerFactory.getLogger(RepositoryStartupServlet.class);

    /**
     * the context attribute name foe 'this' instance.
     */
    private final static String CTX_PARAM_THIS = "repository.startup.servet";

    /**
     * initial param name for the bootstrap config location
     */
    public final static String INIT_PARAM_BOOTSTRAP_CONFIG = "bootstrap-config";

    /**
     * the registered repository
     */
    private Repository repository;

    /**
     * the jndi context; created based on configuration
     */
    private InitialContext jndiContext;

    /**
     * Keeps a strong reference to the server side RMI repository instance to
     * prevent the RMI distributed Garbage Collector from collecting the
     * instance making the repository unaccessible though it should still be.
     * This field is only set to a non-<code>null</code> value, if registration
     * of the repository to an RMI registry succeeded in the
     * {@link #registerRMI()} method.
     *
     * @see #registerRMI()
     * @see #unregisterRMI()
     */
    private Remote rmiRepository;

    /**
     * the file to the bootstrap config
     */
    private File bootstrapConfigFile;

    /**
     * The bootstrap configuration
     */
    private BootstrapConfig config;

    /**
     * Initializes the servlet.<br>
     * Please note that only one repository startup servlet may exist per
     * webapp. it registers itself as context attribute and acts as singleton.
     *
     * @throws ServletException if a same servlet is already registered or of
     * another initialization error occurs.
     */
    public void init() throws ServletException {
        super.init();
        // check if servlet is defined twice
        if (getServletContext().getAttribute(CTX_PARAM_THIS) !=  null) {
            throw new ServletException("Only one repository startup servlet allowed per web-app.");
        }
        getServletContext().setAttribute(CTX_PARAM_THIS, this);
        startup();
    }

    /**
     * Returns an instance of this servlet. Please note, that only 1
     * repository startup servlet can exist per webapp.
     *
     * @param context the servlet context
     * @return this servlet
     */
    public static RepositoryStartupServlet getInstance(ServletContext context) {
        return (RepositoryStartupServlet) context.getAttribute(CTX_PARAM_THIS);
    }

    /**
     * Configures and starts the repository. It registers it then to the
     * RMI registry and bind is to the JNDI context if so configured.
     * @throws ServletException if an error occurs.
     */
    public void startup() throws ServletException {
        if (repository != null) {
            log.error("Startup: Repository already running.");
            throw new ServletException("Repository already running.");
        }
        log.info("RepositoryStartupServlet initializing...");
        try {
            configure();
            initRepository();
            registerRMI();
            registerJNDI();
            log.info("RepositoryStartupServlet initialized.");
        } catch (ServletException e) {
            // shutdown repository
            shutdownRepository();
            log.error("RepositoryStartupServlet initializing failed: " + e, e);
        }
    }

    /**
     * Does a shutdown of the repository and deregisters it from the RMI
     * registry and unbinds if from the JNDI context if so configured.
     */
    public void shutdown() {
        if (repository == null) {
            log.info("Shutdown: Repository already stopped.");
        } else {
            log.info("RepositoryStartupServlet shutting down...");
            shutdownRepository();
            unregisterRMI();
            unregisterJNDI();
            log.info("RepositoryStartupServlet shut down.");
        }
    }

    /**
     * Restarts the repository.
     * @throws ServletException if an error occurs.
     * @see #shutdown()
     * @see #startup()
     */
    public void restart() throws ServletException {
        if (repository != null) {
            shutdown();
        }
        startup();
    }

    /**
     * destroy the servlet
     */
    public void destroy() {
        super.destroy();
        shutdown();
    }

    /**
     * Returns the started repository or <code>null</code> if not started
     * yet.
     * @return the JCR repository
     */
    public Repository getRepository() {
        return repository;
    }

    /**
     * Reads the configuration and initializes the {@link #config} field if
     * successful.
     * @throws ServletException if an error occurs.
     */
    private void configure() throws ServletException {
        // check if there is a loadable bootstrap config
        Properties bootstrapProps = new Properties();
        String bstrp = getServletConfig().getInitParameter(INIT_PARAM_BOOTSTRAP_CONFIG);
        if (bstrp != null) {
            // check if it's a web-resource
            InputStream in = getServletContext().getResourceAsStream(bstrp);
            if (in == null) {
                // check if it's a file
                bootstrapConfigFile = new File(bstrp);
                if (bootstrapConfigFile.canRead()) {
                    try {
                        in = new FileInputStream(bootstrapConfigFile);
                    } catch (FileNotFoundException e) {
                        log.error("Error while opening bootstrap properties: {}", e.toString());
                        throw new ServletException("Error while opening bootstrap properties: " + e.toString());
                    }
                }
            }
            if (in != null) {
                try {
                    bootstrapProps.load(in);
                } catch (IOException e) {
                    log.error("Error while loading bootstrap properties: {}", e.toString());
                    throw new ServletException("Error while loading bootstrap properties: " + e.toString());
                } finally {
                    try {
                        in.close();
                    } catch (IOException e) {
                        // ignore
                    }
                }
            }
        }

        // read bootstrap config
        config = new BootstrapConfig();
        config.init(getServletConfig());
        config.init(bootstrapProps);
        config.validate();
        if (!config.isValid()
                || config.getRepositoryHome() == null
                || config.getRepositoryConfig() == null) {
            if (bstrp == null) {
                log.error("Repository startup configuration is not valid.");
                throw new ServletException("Repository startup configuration is not valid.");
            } else {
                log.error("Repository startup configuration is not valid but a bootstrap config is specified.");
                log.error("Either create the {} file or", bstrp);
                log.error("use the '/config/index.jsp' for easy configuration.");
                throw new ServletException("Repository startup configuration is not valid.");
            }
        }
        config.logInfos();
    }