sql92filter.java

java开源的企业总线.xmlBlaster

/*------------------------------------------------------------------------------
 Name:      Sql92Filter.java
 Project:   xmlBlaster.org
 Copyright: xmlBlaster.org, see xmlBlaster-LICENSE file
 Comment:   Support check of message content with regular expressions.
 ------------------------------------------------------------------------------*/
package org.xmlBlaster.engine.mime.sql92;

import java.util.logging.Logger;
import org.xmlBlaster.util.lexical.Sql92Selector;
import org.xmlBlaster.util.plugin.I_Plugin;
import org.xmlBlaster.util.plugin.PluginInfo;
import org.xmlBlaster.util.XmlBlasterException;
import org.xmlBlaster.util.def.ErrorCode;
import org.xmlBlaster.authentication.SessionInfo;
import org.xmlBlaster.util.def.Constants;
import org.xmlBlaster.util.MsgUnit;
import org.xmlBlaster.engine.mime.I_AccessFilter;
import org.xmlBlaster.engine.mime.Query;
import org.xmlBlaster.engine.ServerScope;

/**
 * This sql92 plugin allows to filter the client properties of the qos
 * expressions of the kind specified in SQL92 for the 'WHERE' selections. It is
 * also conform to the specification of JMS Message Selectors (version 1.1).
 * <p />
 * Please register this plugin in xmlBlaster.properties:
 * 
 * <pre>
 * MimeAccessPlugin[Sql92Filter][1.0] = org.xmlBlaster.engine.mime.sql92.Sql92Filter
 * </pre>
 * 
 * Plugins must implement the I_Plugin interface to be loadable by the
 * PluginManager and must implement the I_AccessFilter interface to be usable as
 * a filter.
 * <p />
 * 
 * @author <a href="mailto:[e-mail]">Michele Laghi</a>
 * @see <a href="http://java.sun.com/products/jms/docs.html" target="others">The
 *      JMS specification</a>
 */
public class Sql92Filter implements I_Plugin, I_AccessFilter {
   private final String ME = "Sql92Filter";

   private ServerScope glob;

   private static Logger log = Logger.getLogger(Sql92Filter.class.getName());

   private PluginInfo pluginInfo;

   private boolean cacheQuery = false;

   /**
    * This is called after instantiation of the plugin
    * 
    * @param glob
    *           The Global handle of this xmlBlaster server instance.
    */
   public void initialize(ServerScope glob) {
      this.glob = glob;

      log.info("Filter is initialized, we check all mime types");
   }

   /**
    * This method is called by the PluginManager (enforced by I_Plugin).
    * 
    * @see org.xmlBlaster.util.plugin.I_Plugin#init(org.xmlBlaster.util.Global,org.xmlBlaster.util.plugin.PluginInfo)
    */
   public void init(org.xmlBlaster.util.Global glob,
         org.xmlBlaster.util.plugin.PluginInfo pluginInfo) {
      this.pluginInfo = pluginInfo;
      try {
         this.cacheQuery = glob.get("cacheQuery", this.cacheQuery, null, this.pluginInfo);
      }
      catch (XmlBlasterException e) {
         log.warning(e.getMessage());
      }
      log.info("Initialized plugin " + getType() + " with cacheQuery=" + this.cacheQuery);
   }

   /**
    * Return plugin type for Plugin loader
    * 
    * @return "Sql92Filter"
    */
   public String getType() {
      return (this.pluginInfo == null) ? "Sql92Filter" : this.pluginInfo
            .getType();
   }

   /**
    * Return plugin version for Plugin loader
    * 
    * @return "1.0"
    */
   public String getVersion() {
      return (this.pluginInfo == null) ? "1.0" : this.pluginInfo.getVersion();
   }

   /**
    * Get a human readable name of this filter implementation
    * 
    * @return "Sql92Filter"
    */
   public String getName() {
      return getType(); // "Sql92Filter";
   }

   /**
    * Get the content MIME type for which this plugin applies
    * 
    * @return "*" This plugin handles all mime types
    */
   public String[] getMimeTypes() {
      String[] mimeTypes = { "*" };
      return mimeTypes;
   }

   /**
    * Get the content MIME version number for which this plugin applies
    * 
    * @return "1.0" (this is the default version number)
    */
   public String[] getMimeExtended() {
      String[] mimeExtended = { Constants.DEFAULT_CONTENT_MIME_EXTENDED }; // "1.0"
      return mimeExtended;
   }

   /**
    * Check if the filter rule matches for this message.
    * 
    * @param publisher
    *           The subject object describing the publisher
    * @param receiver
    *           The subject object describing the receiver
    * @param msgUnit
    *           The message to check
    * @param query
    *           The Query instance holding the regular expression from your
    *           filter.<br />
    * @return true The filter regex expression matches the message content.
    * @exception see
    *               I_AccessFilter#match()
    */
   public boolean match(SessionInfo receiver, MsgUnit msgUnit, Query query)
         throws XmlBlasterException {
      if (msgUnit == null) {
         Thread.dumpStack();
         throw new XmlBlasterException(glob,
               ErrorCode.INTERNAL_ILLEGALARGUMENT, ME,
               "Illegal argument in regex match() call");
      }

      Sql92Selector selector;
      if (this.cacheQuery) {
         if (query.getPreparedQuery() == null) {
            selector = new Sql92Selector(this.glob);
            query.setPreparedQuery(selector); // for better performance we
                                                // remember the regex expression
         } else
            selector = (Sql92Selector) query.getPreparedQuery();
      } else {
         selector = new Sql92Selector(this.glob);
      }

      return selector.select(query.getQuery(), msgUnit.getQosData()
            .getClientProperties());
   }

   public void shutdown() {
   }

}