Begin message signals the Sybase RAP code that a new message is being started.
Each network buffer has one network buffer header to indicate the sequential packet number being sent. Buffering is necessary to ensure multicast ordering and to allow possible resend requests.
The Publisher API encodes each value sent to it via SetField() directly into the wire-ready format buffer. Each successive value of a message is directly appended to make one string to be sent over the network. Since messages may contain as few as 60 characters, multiple messages can be inserted into a single network packet buffer. MTU size is used to determine the packet size.
The following diagram illustrates the role of glue code using the feed handler SetField API to send data to the Publisher. The Publisher API then sends the code out on the network.
