3 - CommunicationSDL-RT is event driven, meaning communication is based on message exchanges. A message has a name and a parameter that is basically a pointer to some data. Messages go through channels that connect agents and end up in the processes implicit queues.
Channels have names and are represented by a one-way or two-ways arrows. A channel name is written next to the arrow without any specific delimiter. The list of messages going in a specific way are listed next to the arrow between brackets and separated by commas. Messages can be gathered in message lists, to indicate a message list in the list of messages going through a channel the message list is surrounded by parenthesis. Note the same message can be listed in both directions.
Let us consider an SDL-RT system made of two blocks: blockA and blockB.