|
This glossary uses the situation of people in a business meeting
as a metaphor for terms in the area of time-triggered systems:
Babbling Idiot
Meeting member who does not stop speaking nonsense
Bus Guardian
Meeting timer who allows people to speak within their predefined
time frame
Byzantine Failure
Is a failure where some meeting members receive a message different
from other messages
Cluster
All meeting participants taken together
Cluster Cycle
In TTP one full communication round where every meeting member speaks
once is called a TDMA round. After a predefined number of TDMA rounds
the same messages are repeated. This is called a cluster cycle.
Consistency
In the meeting all people know about the information each of the
other participants have. They all plan their actions on the basis
of the information available to all.
Fault Tolerance
Any component in a system can fail. TTP is designed to tolerate
any failure.
Frame
One communication sequence of one of the meeting participants consisting
of one or several messages
Jitter
Difference between the maximum and minimum duration of an action
Message Descriptor List (MEDL)
Meeting timer or agenda covering the detailed timing of the meeting.
The MEDL does not give any restrictions regarding the content or
semantics of the messages.
Membership
List of correct (sane) meeting participants. In the meeting every
participant starts his communication with a list of the other participants
who he thinks receive and send meaningful information. By checking
the list he receives from the other participants he can make sure
if his information was received successfully.
Node
Meeting participant
Slightly Off Specification (SOS) fault
One node sends a signal that is at the edge of what the receiver
understands as "1" or "0". For example, in a
5V system the limit might be specified at 4.5V. If a signal is exactly
4.5V, some receivers might understand "1" and others "0".
Time division multiple access (TDMA)
round
One round of communication in which every member has had a chance
to speak
|
