Product: OpenFusion Notification Service

Version: ALL

Description:

How to create a channel with a specific ID?

Resolution:

The Notification Service specification does not provide a method to create a channel with a predefined number.

The create_channel() method is the only method used to create an event channel and it automatically assigns a numeric identifier to the channel.

For example:

  factory = EventChannelFactoryHelper.narrow(obj);

  try
  {
    channel = factory.get_event_channel(3);
  }
  catch (ChannelNotFound ex)
  {
    // Create a channel with no QoS or admin properties.
    Property[] qosProp = new Property[0];
    Property[] admProp = new Property[0];
    org.omg.CORBA.IntHolder id = new org.omg.CORBA.IntHolder ();

    try
    {
      channel = factory.create_channel (qosProp, admProp, id);
    }
    catch (UnsupportedQoS exc)
    { }
    catch (UnsupportedAdmin exc)
    { }
  }

This code tries to get channel number 3. The first time the code is run channel 3 does not exist so the ChannelNotFound exception is thrown.

The create_channel() method will create channel 0 as this is the first available number for it to use.

The next time the code is run channel 3 still does not exist so the create_channel() method will create channel number 1.

This will continue until channel 3 is created. As soon as channel 3 exists then every time you run the code the get_event_channel() method will find channel 3 and the exception will not be thrown.