public TrapFactorySupport() 
{
      this.snmpVBFactory = new SnmpVarBindFactory();
}

Create TrapFactorySupport *

 public SnmpPduTrap generateV1Trap(Notification n) throws MappingFailedException 
{
      if (log.isTraceEnabled())
         log.trace("generateV1Trap");
      // Locate mapping for incomming event
      int index = -1;
      try
      {
         index = findMappingIndex(n);
      }
      catch (IndexOutOfBoundsException e)
      {
         throw new MappingFailedException("No mapping found for notification type: '" + 
                    n.getType() + "'");
      }
      Mapping m = (Mapping)this.notificationMapList.get(index);
      // Create trap
      SnmpPduTrap trapPdu = new SnmpPduTrap();
      trapPdu.setTimeStamp(this.clock.uptime());
      // Organise the 'variable' payload 
      trapPdu.setGeneric(m.getGeneric());
      trapPdu.setSpecific(m.getSpecific());
      trapPdu.setEnterprise(m.getEnterprise());
      // Append the specified varbinds. Get varbinds from mapping and for
      // each one of the former use the wrapper to get the corresponding
      // values
      // Get the coresponding wrapper to get access to notification payload
      NotificationWrapper wrapper =
         (NotificationWrapper)this.notificationWrapperCache.get(index);
      if(wrapper != null)
      {
         // Prime the wrapper with the notification contents
         wrapper.prime(n);
         // Iterate through mapping specified varbinds and organise values
         // for each
         List vbList = m.getVarBindList().getVarBindList();
         for (int i = 0; i <  vbList.size(); i++)
         {
            VarBind vb = (VarBind)vbList.get(i);
            // Append the var bind. Interrogate read vb for OID and 
            // variable tag. The later is used as the key passed to the 
            // wrapper in order for it to locate the required value. That 
            // value and the aforementioned OID are used to generate the 
            // variable binding
            trapPdu.addVarBind(
               this.snmpVBFactory.make(vb.getOid(), wrapper.get(vb.getTag())));
         }
      }
      else
      {
         throw new MappingFailedException(
            "Varbind mapping failure: null wrapper defined for " +
            " notification type '" + m.getNotificationType() + "'" );
      }
      return trapPdu;
}

Traslates a Notification to an SNMP V1 trap. *

 public SnmpPduPacket generateV2Trap(Notification n) throws MappingFailedException 
{
      if (log.isTraceEnabled())
         log.trace("generateV2Trap");
      // Locate mapping for incomming event
      int index = -1;
      try
      {
         index = findMappingIndex(n);
      }
      catch (IndexOutOfBoundsException e)
      {
         throw new MappingFailedException(
            "No mapping found for notification type: '" + n.getType() + "'");
      }
      Mapping m = (Mapping)this.notificationMapList.get(index);
      // Create trap
      SnmpPduRequest trapPdu = new SnmpPduRequest(SnmpPduPacket.V2TRAP);
      // Append the specified varbinds. Get varbinds from mapping and for
      // each one of the former use the wrapper to get data from the 
      // notification
      // Get the coresponding wrapper
      NotificationWrapper wrapper =
         (NotificationWrapper)this.notificationWrapperCache.get(index);
      if (wrapper != null)
      {
         // Prime the wrapper with the notification contents
         wrapper.prime(n);
         List vbList = m.getVarBindList().getVarBindList();
         for (int i = 0; i <  vbList.size(); i++)
         {
            VarBind vb = (VarBind)vbList.get(i);
            // Append the var bind. Interrogate read vb for OID and 
            // variable tag. The later is used as the key passed to the 
            // wrapper in order for it to locate the required value. That 
            // value and the aforementioned OID are used to generate the 
            // variable binding
            trapPdu.addVarBind(
               this.snmpVBFactory.make(vb.getOid(), wrapper.get(vb.getTag())));
         }
      }
      else
      {
         log.warn("Varbind mapping failure: null wrapper defined for " +
                  " notification type '" + m.getNotificationType() + "'" );
      }
      return trapPdu;
}

Traslates a Notification to an SNMP V2 trap. TODO: how do you get timestamp, generic, and specific stuff in the trap

 public  void set(String notificationMapResName,
    Clock clock,
    Counter count) 
{
      this.notificationMapResName = notificationMapResName;
      this.clock = clock;
      this.trapCount = count;
}

Sets the name of the file containing the notification/trap mappings, the uptime clock and the trap counter

 public  void start() throws Exception 
{
      log.debug("Reading resource: '" + notificationMapResName + "'");
      ObjectModelFactory omf = new NotificationBinding();
      InputStream is = null;
      try
      {
         // locate notifications.xml
         is = this.getClass().getResourceAsStream(notificationMapResName);
         // create unmarshaller
         Unmarshaller unmarshaller = UnmarshallerFactory.newInstance().newUnmarshaller();
         // let JBossXB do it's magic using the MappingObjectModelFactory
         this.notificationMapList = (ArrayList)unmarshaller.unmarshal(is, omf, null);         
      }
      catch (Exception e)
      {
         log.error("Accessing resource '" + notificationMapResName + "'");
         throw e;
      }
      finally
      {
         if (is != null)
         {
            // close the XML stream
            is.close();            
         }
      }
      log.debug("Found " + notificationMapList.size() + " notification mappings");   
      // Initialise the cache with the compiled regular expressions denoting 
      // notification type specifications
      this.mappingRegExpCache = 
         new ArrayList(notificationMapList.size());
      // Initialise the cache with the instantiated notification wrappers
      this.notificationWrapperCache =
         new ArrayList(notificationMapList.size());
      for (Iterator i = notificationMapList.iterator(); i.hasNext(); )
      {
         Mapping mapping = (Mapping)i.next();
         // Compile and add the regular expression
         String notificationType = mapping.getNotificationType();
         try
         {
            Pattern re = Pattern.compile(notificationType);
            this.mappingRegExpCache.add(re);
         }
         catch (PatternSyntaxException e)
         {
            // Fill the slot to keep index count correct
            this.mappingRegExpCache.add(null);
            log.warn("Error compiling notification mapping for type: " + notificationType, e); 
         }
         // Instantiate and add the wrapper
         // Read wrapper class name 
         String wrapperClassName = mapping.getVarBindList().getWrapperClass();
         log.debug("notification wrapper class: " + wrapperClassName);
         try
         {
            NotificationWrapper wrapper =
               (NotificationWrapper)Class.forName(wrapperClassName, true, this.getClass().getClassLoader()).newInstance();
            // Initialise it
            wrapper.set(this.clock, this.trapCount);
            // Add the wrapper to the cache
            this.notificationWrapperCache.add(wrapper);
         }
         catch (Exception e)
         {
            // Fill the slot to keep index count correct
            this.notificationWrapperCache.add(null);
            log.warn("Error compiling notification mapping for type: " + notificationType, e);  
         }
      }
      log.debug("Trap factory going active");
}

Populates the regular expression and wrapper instance collections. Note that a failure (e.g. to compile a regular expression or to instantiate a wrapper) generates an error message. Furthermore, the offending expression or class are skipped and the corresponding collection entry is null. It is the user's responsibility to track the reported errors in the logs and act accordingly (i.e. correct them and restart). If not the corresponding mappings are effectively void and will NOT have effect.