The concept of a file is important in the delivery of messages. Senders can scope a message to a file and the ToolTalk service will deliver it to all processes that have message patterns that reference the file without regard to the process's default session. To update message patterns with the current file path name, applications join the file.
You can also scope a message to a file within a session. The ToolTalk service will deliver the message to all processes that reference both the file and session in their message patterns.