The five W's of the paradigm: What Why hoW When Who
Why is flexibility important ?
In the domain of industrial communication systems, flexibility is considered a way to:
- Reduce costs associated to set-up, configuration changes and maintenance
- Improve the resource efficiency usage
- Resources can be allocated in a "as needed basis" fashion
- No over-provision is required
- Online QoS management is possible
- Manage system complexity
- No need to predefine an exhaustive (but necessarily limited) set of modes
- Support to open/dynamic environments
- Increasing number of inherently dynamic applications, in which nodes join and departure at runtime
What is flexibility ?
Flexibility means the "ability to make changes or to deal with a situation that is changing" (Macmillan dictionary)
For industrial communication networks flexibility translates to:
- Add and/or remove message streams
- Modify attributes on existing message streams
- E.g. change the period or deadline
- Support different traffic types ( Time-Triggered, Event-Triggered) with different criticality levels (Real-Time, Non Real-Time)
- Support the plug/unplug of nodes from the network
All of this online and without disrupting communications!
How to support flexibility while guaranteeing real-time requirements ?
Centralized architecture to coordinate the network, composed of :
- A System Requirements Database (SRDB)
- An online scheduler that operates on the SRDB
- A set of primitives to update the SRDB
- An online admission control that rejects non-feasible changes
- An (optional) online QoS manager and a mechanism to broadcast the schedule through the network
Who and When ?
The Flexible Time-Triggered protocol family has been essentially developed at the University of Aveiro, by the Electronic Systems Laboratory team,
Main contributors :