Chapter 7. The Replicator
The Replicator provides the transactional replication from one grid to another, based on CloudTran transactions.
Replication goes from the "local" Grid to a "remote" Grid.
The replicator is specifically for "system of record in the grid" applications that are concerned with preserving transactional consistency at a remote grid.
The key characteristics of the replicator are:
- If the system of record is the database, it makes more sense to use a database-driven replication approach, like GoldenGate.
- If you are not concerned about transactionality, using the standard Coherence replication is more appropriate.
The replicator is an optional feature: it must be switched on to become active.
This chapter explains how the CloudTran Replicator functions and how to configure the various aspects of the Replicator.
- "Replicate-behind". In other words, the replicator does not wait for an acknowledgement from the remote grid that a transaction has committed,
before committing at the local grid. This avoids long transactional delays (of 100ms or more).
- Replicator-specific transaction log, which *is* committed before the local transaction is committed.
This adds a very small delay (less than the time for one network message on average, if SSD drives are used).
- No single point of failure - dual drives can be used, and the replicator is provided as a service that fails over.
- Active-Passive and Active-Active configurations supported.
Previous values are sent along with changed values so double-update conflicts can be detected.
7.1 Replicator Overview
7.2 Local Store