webapp/fmprod/src/main/java/org/apache/oodt/cas/product/jaxrs/servlets/CasProductJaxrsServlet.java

/*
 * 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.oodt.cas.product.jaxrs.servlets;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.concurrent.ConcurrentHashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;

import org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet;
import org.apache.oodt.cas.filemgr.structs.exceptions.ConnectionException;
import org.apache.oodt.cas.filemgr.system.FileManagerClient;
import org.apache.oodt.cas.filemgr.util.RpcCommunicationFactory;
import org.apache.oodt.cas.metadata.util.PathUtils;
import org.apache.oodt.cas.product.jaxrs.configurations.RdfConfiguration;
import org.apache.oodt.cas.product.jaxrs.configurations.RssConfiguration;

/**
 * Provides a single place to initialize items such as the file manager client,
 * working directory and configurations when the web application is started up.
 * @author rlaidlaw
 * @version $Revision$
 */
public class CasProductJaxrsServlet extends CXFNonSpringJaxrsServlet
{
  // Auto-generated ID for serialization.
  private static final long serialVersionUID = -1835790185000773396L;

  private static final Logger LOGGER = Logger.getLogger(CasProductJaxrsServlet
    .class.getName());

  private static final int CONFIG_PARAM_LENGTH = 3;
  private static final int CONFIG_PARAM_FORMAT = 1;
  private static final int CONFIG_PARAM_NAME = 2;


  @Override
  public void init(ServletConfig configuration) throws ServletException
  {
    super.init(configuration);
    ServletContext context = configuration.getServletContext();
    initializeClient(context);
    initializeWorkingDir(context);
    initializeConfigurations(context);
  }



  /**
   * Initializes the file manager client and stores it as a "client" context
   * attribute by retrieving a value for the file manager URL from the servlet
   * context.
   * @param context the servlet context
   * @throws ServletException if the servlet context parameter for the file
   * manager working directory path cannot be found
   */
  private void initializeClient(ServletContext context) throws ServletException
  {
    try
    {
      URL url;
      String urlParameter = context.getInitParameter("filemgr.url");
      if (urlParameter != null)
      {
        // Get the file manager URL from the context parameter.
        url = new URL(PathUtils.replaceEnvVariables(urlParameter));
      }
      else
      {
        // Try the default URL for the file manager.
        LOGGER.log(Level.WARNING, "Unable to find a servlet context parameter "
          + "for the file manager URL.");
        url = new URL("http://localhost:9000");
      }

      // Attempt to connect the client to the file manager and if successful
      // store the client as a context attribute for other objects to access.
      FileManagerClient client = RpcCommunicationFactory.createClient(url);
      context.setAttribute("client", client);
    }
    catch (MalformedURLException e)
    {
      String message = "Encountered a malformed URL for the file manager.";
      LOGGER.log(Level.SEVERE, message, e);
      throw new ServletException(message);
    }
    catch (ConnectionException e)
    {
      String message =
        "Client could not establish a connection to the file manager.";
      LOGGER.log(Level.SEVERE, message, e);
      throw new ServletException(message);
    }
  }



  /**
   * Initializes the file manager working directory path and stores it as a
   * "workingDir" context attribute by retrieving a value from the servlet
   * context.
   * @param context the servlet context
   * @throws ServletException if the servlet context parameter for the file
   * manager working directory path cannot be found
   */
  private void initializeWorkingDir(ServletContext context)
    throws ServletException
  {
    String workingDirPath = context.getInitParameter("filemgr.working.dir");
    if (workingDirPath != null)
    {
      // Validate the path.
      File workingDir = new File(PathUtils.replaceEnvVariables(workingDirPath));
      if (workingDir.exists() && workingDir.isDirectory())
      {
        context.setAttribute("workingDir", workingDir);
        LOGGER.log(Level.FINE, "The file manager's working directory has been "
          + "set up as " + workingDir.getAbsolutePath());
      }
      else
      {
        LOGGER.log(Level.SEVERE, "Unable to locate the working directory for "
          + "the file manager.");
      }
    }
    else
    {
      String message = "Unable to find a servlet context parameter for the file"
        + " manager working directory path.";
      LOGGER.log(Level.SEVERE, message);
      throw new ServletException(message);
    }
  }



  /**
   * Initializes the output configurations for various different formats and
   * stores them in "configurations" attributes by retrieving values from the
   * servlet context.
   * @param context the servlet context
   * @throws IOException if the specified file cannot be found or read
   */
  public void initializeConfigurations(ServletContext context)
  {
    Map<String, RdfConfiguration> rdfConfigurations =
      new ConcurrentHashMap<String, RdfConfiguration>();
    Map<String, RssConfiguration> rssConfigurations =
      new ConcurrentHashMap<String, RssConfiguration>();

    Enumeration<String> enumeration = context.getInitParameterNames();
    while (enumeration.hasMoreElements())
    {
      String parameterName = enumeration.nextElement();
      if(parameterName.startsWith("configuration"))
      {
        String[] values = parameterName.split("\\.");
        if (values.length == CONFIG_PARAM_LENGTH)
        {
          String format = values[CONFIG_PARAM_FORMAT];
          String name = values[CONFIG_PARAM_NAME];
          String value = PathUtils.replaceEnvVariables(
            context.getInitParameter(parameterName));

          try
          {
            if ("rdf".equals(format))
            {
              RdfConfiguration configuration = new RdfConfiguration();
              configuration.initialize(new File(value));
              rdfConfigurations.put(name, configuration);
            }
            else if ("rss".equals(format))
            {
              RssConfiguration configuration = new RssConfiguration();
              configuration.initialize(new File(value));
              rssConfigurations.put(name, configuration);
            }
          }
          catch (IOException e)
          {
            LOGGER.log(Level.WARNING, "The configuration '" + parameterName
              + "'could not be initialized (value: " + value + ").", e);
          }
        }
        else
        {
          LOGGER.log(Level.FINE,
            "Configuration context parameter could not be parsed.");
        }
      }
    }

    context.setAttribute("rdfConfigurations", rdfConfigurations);
    context.setAttribute("rssConfigurations", rssConfigurations);
  }
}