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db4o - Database for Complex Event Processing

Complex Event Processing (CEP) is a technology for low-latency filtering, correlating, aggregating, and computing on real- world event data.

These systems are usually complex enough to require a database for historical processing, namely:

  • Storing events for historical analysis
  • Storing the queries/rules for re-usability
  • Testing queries on past events enabling modeling
  • Storing configurations
  • Generating reports and views – aggregate / callbacks
  • Failing over and replay of events
  • Integrating and correlating multiple sources of events
  • Allowing users to query directly and mine the data

If you require guidance on how to use db4o in your event processing application please:


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A perfect match for your CEP application

A lightweight, robust and fast persistence engine like db4o is the perfect companion for CEP systems offering:

  • Native storage of complex objects. Objects are stored as they come through the pipeline (no conversion or mapping required) which makes the system as a whole more suitable for real time processing of events
  • Speed. Up to 200,000 objects per second
  • Support for callbacks which allow the database to also react to events occurring in the CEP system providing a flexible and adaptive mechanism for triggers
  • Embedded or C/S mode. You don't have to set up a database server if you don't need to. You can use db4o in a blazingly fast embedded mode or you can run db4o as a server and fetch/send data from clients
  • Replication enables your data to be distributed and kept in sync among different datasources (either with db4o instances or relational databases)
  • Schema evolution and refactoring. Flexible and implicit schema allows quick adaptation of the rules while maintaining the context of the past
  • Native queries interface provides for full power of programming languages for expressing rules and triggers, such as handling hierarchical array of features detectors
  • Support tools. A database browser and query builder like OME allows you to test the results to ease development


Proven technology for CEP use cases:

From SCADA to Trading and Risk Management systems db4o's versatility enabled innovators and system integrators to provide state-of-the-art object persistence for a fraction of the cost and time.


"Our order and quote management system combines an embedded object-based continuous event processor with an embedded object database [db4o]. This allows us to rapidly add new derivative products to our environment and keeps developers focused on writing code that adds direct business value. With our design, we have strived to eliminate "non-productive" development: keeping objects in sync with a relational datamodel adds no value to our business, so we rely on object database technology to make that problem go away. We have found this approach not only enables us to deliver incremental functionality faster, but also reduces our testing burden since there are fewer moving parts for us to maintain ourselves.

For us, the choice to use an object database has directly increased our ability to deliver business solutions in the shortest time possible."

                — Richard Ahrens (Director at Merrill Lynch) in ODBMS.ORG