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diff --git a/protocols/ace/TMCast/README b/protocols/ace/TMCast/README deleted file mode 100644 index 43e35c52388..00000000000 --- a/protocols/ace/TMCast/README +++ /dev/null @@ -1,58 +0,0 @@ - - -Architecture - -TMCast (stands for Transaction MultiCast) is an implementation of a -transactional multicast protocol. In essence, the idea is to represent -each message delivery to members of a multicast group as a transaction - -an atomic, consistent and isolated action. A multicast transaction can -be viewed as an atomic transition of the group members to a new state. -If we define [Mo] as a set of operational (non-faulty) members of the -group, [Mf] as a set of faulty members of the group, [Ma] as a set of -members that view transition [Tn] as aborted and [Mc] as a set of members -that view transition [Tn] as committed, then this atomic transition [Tn] -should satisfy one of the following equations: - -Mo(Tn-1) = Ma(T) U Mf(T) -Mo(Tn-1) = Mc(T) U Mf(T) - -Or, in other words, after transaction T has been committed (aborted), -all operational (before transaction T) members are either in the -committed (aborted) or failed state. - -Thus, for each member of the group, outcome of the transaction can -be commit, abort or a member failure. It is important for a member -to exhibit a failfast (error latency is less than transaction cycle) -behavior. Or, in other words, if a member transitioned into a wrong -state, it is guaranteed to fail instead of delivering a wrong result. - -In order to achieve such an error detection in a decentralized -environment, certain limitations were imposed. One of the most -user-visible limitation is the fact that the lifetime of the group -with only one member is very short. This is because there is not way -for a member to distinguish "no members yet" case from "my link to the -group is down". In such a situation, the member assumes the latter case. -There is also a military saying that puts it quite nicely: two is one, -one is nothing. - - -State of Implementation - -The current implementation is in a prototypical stage. The following -parts are not implemented or still under development: - -* Handling of network partitioning (TODO) - -* Redundant network support (TODO) - -* Member failure detection (partial implementation) - - -Examples - -There is a simple example available in examples/TMCast/Member with -the corresponding README. - - --- -Boris Kolpackov <boris@dre.vanderbilt.edu> |