Distributed Graph Transformation With Application to Visual Design of Distributed Systems

A graph-based algorithm for consistency maintenance in incremental and interactive integration tools

“…The formalism of distributed graph transformations [38] is used to model view points and their interrelations, especially consistency checks and repair actions. To the best of our knowledge, this approach works incrementally but does not support detection of conflicting rules and user interaction.…”

Modelling and Analysis of Distributed Simulation Protocols with Distributed Graph Transformation

“…[1] LocalVirtualTime.time = 0 // Simulation time for component [2] EventQueue.first = Initial Event // Event queue is initially empty [3] for all i in InputPort: i.clock = 0 // Set clocks for each port to 0 [4] ExecutionPointer.STEP() // Do one step, inserting internal events in queue [5] while LocalVirtualTime.timeHorizon < LocalVirtualTime.finalTime: // loop until simulation final time [6] for all i in InputPort: await not_empty(i) // wait for an event in the input port [7] for all i in InputPort: i.clock=max_timeStamp(i) // i.clock is the bigger timeStamp of any event in i [8] LocalVirtualTime.timeHorizon=min(i.clock for i in InputPort) // The process time horizon is the smaller clock of all ports [9] min_channel_id = i such that its clock is the smallest [10] if (Event.Queue.first.scheduledTime <= LocalVirtualTime.timeHorizon) [11] or (InputPort [min_channel_id].first.scheduledTime <= [12] LocalVirtualTime.timeHorizon): [13] if (Event.Queue.first.scheduledTime < [14] InputPort [min_channel_id].first.scheduledTime): [15] event = removeFirst(Event.Queue) [16] else In conservative protocols, LPs have a time horizon, which is the maximum simulation time it is safe to reach. Beyond this point causality errors may occur with incoming events.…”

“…While the basics of graph transformation are regular graphs, in DGT [16] distributed graphs are transformed by means of distributed rules. A distributed graph has two levels of abstraction.…”

“…These consist of a network rule and a set of local rules, one for each node in the network rule left hand side (LHS) [16]. Thus, a distributed typed attributed rulep = (Ll ←−Kr −→R) consists of two injective Dist(AGr) TG -morphismsl andr such that ∀i ∈ K V1 (i.e.…”

“…Transformations expressed as graph grammars become formal, declarative, high-level and graphical models, subject themselves to analysis. Distributed graph transformation [16] (DGT) was developed with the aim to naturally express computations in systems made of interacting parts. In this way, a distributed graph has two levels: a network and a local level.…”