Each subscriber has two components: the open subscriber and a data stream handler. The open subscriber handles interface issues and queues messages for the data stream handler, and the data stream handler routes the messages to their final destination.
Each data stream listens for packets on one UDP broadcast channel. When a packet arrives on a channel, the subscriber checks and records the packet sequence number to determine whether any packets are missing. If a packet is missing, the subscriber asks the publisher to resend the missing packet on the publisher resend channel.
RAP includes two data stream handlers: the RAPCache data stream handler and the RAPStore data stream handler. The RAPCache data stream handler loads messages into Adaptive Server. The Store data stream handler loads messages into Sybase IQ. The demo subscriber component includes a demo data stream handler that you can configure to write messages to a file, or discard messages.