Oracle has released the core of their Coherence in-memory data grid (IMDG) product as free and open source software.
Named Coherence Community Edition, it has been released under the Open Source Initiative’s Universal Permissive License, Version 1.0, and is hosted on GitHub.
In its simplest form, an IMDG can be thought of as a Java Map that extends across multiple virtual machines and may optionally be persisted to disk. This simple mental model allows developers to quickly on-ramp to the technology, although the complexities of general distributed computing cannot be completely ignored (especially for advanced use cases).
The open source Coherence release provides a very familiar set of core IMDG features, including:
- Parallel querying and aggregation
- Fault-tolerant automatic sharding
- Caching, querying, aggregation, transactions, in-place processing
- Persistence
- Eventing, messaging, and streaming
Similar to competing offerings in the IMDG space, Oracle has chosen a freemium model, with certain enterprise features being restricted to their Enterprise or Grid editions which are only available to paying customers.
Oracle clearly intends to bring Coherence back into the consciousness of Java / JVM developers working in microservice architectures. As part of this repositioning, they promise an extensive range of integrations with their other technology offerings, including Helidon, GraalVM, Oracle Database and Database Cloud.
To showcase the simplifications that they believe an in-memory data grid, such as Coherence, can bring to modern architectures, Oracle is including a microservices demo app, named Helidon Sock Shop.
Coherence was originally developed by Cameron Purdy and others at Tangosol, which was acquired by Oracle in 2007.
Developers can get a lot more information about the release at the Coherence Community website.