Symmetric distributed applications

Symmetric Peer-to-Peer Applications

“…We propose a middleware to program symmetric peer-to-peer applications in which interacting peers conform to identical behavior without a centralized coordination server. The middleware API shares similar limitations with centralized alternatives [1,2], being restricted to deterministic and stateless calls. Our main contribution is a time machine that supports rollbacks based on memory snapshots and deterministic simulation.…”

“…GALS [1] shares the same goals with Croquet, but with some tradeoffs, mostly favoring clients with slow connections. As detailed in Figure 2, instead of advancing ticks in sync with the server, clients have their own independent local clocks.…”

“…On the other hand, events take longer to apply and clients may experience occasional freezes. The syncing protocol also requires extra bookkeeping to deal with clock drifts and client disconnections [1]. As indicated in Figure 1, GALS also relies on a centralized network (a), but in which nodes advance time independently (b), and in which event broadcasts and outcomes still depend on the central server to be online (c).…”

“…Real-time networked applications allow multiple users to interact remotely and yet share the same experience. Examples of these symmetric distributed applications [1] are collaborative documents, watch parties, and multi-player games. In order to reproduce the exact behavior in multiple devices, the application must be able to synchronize time and execution across the network.…”

“…A common approach towards symmetric applications is to introduce a middleware to orchestrate events and time in the network [1,2]. This way, applications developers can rely on middleware primitives to trigger events, which are intercepted and synchronized in a global shared timeline across the network.…”