In this chapter you learned about the two forms of replication that are supported. First, we examined the basic replication between db4o ObjectContainers. This is a straightforward process that only requires UUIDs, versions, a conflict handler, and a replication object to get your objects replicated. The second form is provided by the dRS (db4o Replication System), which also lets you connect db4o to relational databases. You have seen a simple example that writes objects from a local db4o database to a relational database system using Hibernate.
The application areas for dRS are wide. The obvious scenario is that of mobile, disconnected, or partially connected devices that capture data in a db4o database, and then later replicate this data into their RDBMS in the office. There are many more possible scenarios: for example, dRS has been used by companies to transfer specific content between different RDBMSs. Give some thought to dRS and see what might it be able to do for you.
The next chapter rounds off Part II of this book by giving you a tour of some of the advanced features of db4o, from indexing to encryption and pluggable input/output.
KeywordsRelational Database Replication Process Remote Server Version Number Mapping File
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