Tuplespace middleware for Petri net-based workflow execution

FaCETa: Backward and Forward Recovery for Execution of Transactional Composite WS

“…Figure 3 roughly depicts the overall architecture. By distributing the responsibility of executing a TCWS across several Engine Threads, the logical model of our Executer allows distributed execution of a TCWS and is independent of its implementation, i.e., this model can be implemented in a distributed memory environment supported by message passing (see Figure 4(a)) or in a shared memory platform, e.g., supported by a distributed shared memory [22] or tuplespace [19] systems (see Figure 4(b)). The idea is to place the Executer in different physical nodes (e.g., a high available and reliable cluster computing) from those where actual WSs are placed.…”

“…In the first one, nodes interact directly based on a peer-to-peer application architecture and collaborate, in order to execute a CWS with every node executing a part of it [2,5,16,18,28]. In the second one, they use a shared space for coordination [4,12,19].…”

“…Another series of works rely on a shared space to exchange information between nodes of a decentralized architecture, more specifically called a tuple space [12,19]. The notion of a tuplespace is a piece of memory shared by all interacting parties.…”

“…Thus, the templates a component uses to consume tuples, together with the tuples it produces, represent its coordination logic. In [19] approach to replace a centralized BPEL engine by a set of distributed, loosely coupled, cooperating nodes, is presented. This approach presents a coordination mechanism where the data is managed using a tuplespace and the control is driven by asynchronous messages exchanged between nodes.…”

“…This message exchange pattern for the control is derived from a Petri Net model of the workflow. In [19], the workflow definition is transformed into a set of activities, that are distributed by passing tokens in the Petri Net. In [12] an alternative approach is presented, based on the chemical analogy.…”