  This paper addresses the online monitoring of distributed component-based
systems with multi-party interactions against user-provided properties
expressed in linear-temporal logic and referring to global states. We consider
intrinsically independent components whose interactions are partitioned on
distributed controllers. In this context, the problem that arises is that a
global state of the system is not available to the monitor. Instead, we attach
local controllers to schedulers to retrieve the concurrent local traces. Local
traces are sent to a global observer which reconstructs the set of global
traces that are compatible with the local ones, in a concurrency-preserving
fashion. In this context, the reconstruction of the global traces is done
on-the-fly using a lattice of partial states encoding the global traces
compatible with the locally-observed traces. We implemented our monitoring
approach in a prototype tool called RVDIST. RVDIST executes in parallel with
the distributed model and takes as input the events generated from each
scheduler and outputs the evaluated computation lattice. Our experiments show
that, thanks to the optimisation applied in the online monitoring algorithm, i)
the size of the constructed computation lattice is insensitive to the the
number of received events, (ii) the lattice size is kept reasonable and (iii)
the overhead of the monitoring process is cheap.
