Examples
One well-known example of a system based on optimistic replication is the CVS version control system, or any other version control system which uses the copy-modify-merge paradigm. CVS covers each of the five elements:
- Operation submission: Users edit local versions of files.
- Propagation: Users manually pull updates from a central server, or push changes out once the user feels they are ready.
- Scheduling: Operations are scheduled in the order that they are received by the central server.
- Conflict resolution: When a user pushes to or pulls from the central repository, any conflicts will be flagged for that user to fix manually.
- Commitment: Once the central server accepts the changes which a user pushes, they are permanently committed.
A special case of replication is synchronization, where there are only two replicas. For example, personal digital assistants (PDAs) allow users to edit data either on the PDA or a computer, and then to merge these two datasets together. Note, however, that replication is a broader problem than synchronization, since there may be more than two replicas.
Other examples include:
- Usenet, and other systems which use the Thomas Write Rule (See Rfc677)
- Multi-master database replication
- The Coda distributed filesystem
- Operational Transformation, a theoretical framework for group editing
- Peer-to-peer wikis
- The Bayou distributed database
- IceCube
Read more about this topic: Optimistic Replication
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