Broadcasting Messages

Broadcasting is one of two modes of operation on SunNET. This mode is usually not accessible to non-wizards. I consider it the lower level of operation since all other communication depends upon it, but it has the advantage of being able.

The broadcasting verb.

There is one verb for transmitting a broadcast.

• $sunnet_utils:broadcast(STR destination, STR protocol, ANY message, [OBJ ack object, STR ack verb, [OBJ fail object, STR fail verb]])
  This verb takes either three, five, or seven arguments. The first is always the destination site for the packet. The special site GENERAL may be used to send a packet to all sites. The second is the protocol for the message. The third is the packet message which can be any legal MOO value. Be warned that some values may not translate if your MOO has special server hacks to implement non-standard values. Following those three required arguments, you can specify an ACK handler (or success handler) or a FAIL handler. The ACK handler is called when a packet is transmitted successfully while the FAIL handler is called when a packet does not appear to have gotten through. If you specify a fail handler you should specify and ACK handler. If you enter a #-1 for the object, either handler will be ignored. These handlers are also referred to as call-backs. This verb returns the packet id for the message you sent.

Call-Back verbs for broadcasts

For each broadcast, you can specify two verbs (See above). One verb is the ACK call-Back and the second is the FAIL call-back.

• The ACK Handler

  obj:callback(id, pathto, pathfrom, senttime)
  The id is the packet id originally returned by the $sunnet_utils:broadcast verb. settime is the timestamp of the packet. (You can use this by comparing it with time() to see how long it took for the remote site to respond.. It could possibly be used as a measurement of NetLag.) pathto and pathfrom will usually be mirrors of one another provided they are the fastest path from the local site to the remote site. The first is the path followed to the MOO while the second is the path from the MOO. If either is blank then the packet was sent as a GENERAL destination packet. This can be used with the association method listed below to clear the association.

• The FAIL Handler

  obj:callback(id, pathto, pathfrom, senttime)
  The id is the packet id originally returned by the $sunnet_utils:broadcast verb. settime is the timestamp of the packet. pathto and pathfrom are not applicable as the packet was not sent anywhere so they will always be empty lists. A sample use of the fail handler would be to resend important packets. Since the Id is returned on calling $sunnet_utils:broadcast, it would be fairly easy to associate the packet message with that id. Then when the fail handler is called, the program could wait a moment then resend the data.