Xenon is both a set of software components and a service oriented design pattern. The runtime is implemented in Java and acts as the host for the lightweight, asynchronous services. The programming model is language agnostic (does not rely on Java specific constructs) so implementations in other languages are encouraged.

Each service has less than 500 bytes of overhead and can be paused/resumed, making Xenon able to host millions of service instances even on a memory constrained environment.

Service authors annotate their services with various service options, acting as requirements on the runtime, and the framework implements the appropriate algorithms to enforce them. The runtime exposes each service with a URI and provides utility services per instance, for stats, reflection, subscriptions and configuration. A built-in load balancer routes client requests between nodes, according to service options and plug-able node selection algorithms. Xenon supports multiple, independent node groups, maintaining node group state using a scalable gossip scheme.

A powerful index service, invoked as part of the I/O pipeline for persisted services, provides a multi version document store with a rich query language.

High availability and scale-out is enabled through the use of a consensus and replication algorithm and is also integrated in the I/O processing.

The lightweight runtime enables the creation of highly available and scalable applications in the form of cooperating light weight services. The operation model for a cluster of Xenon nodes is the same for both on premise, and service deployments.

The photon controller project makes heavy use of Xenon to build a scalable and highly available Infrastructure-as-a-Service fabric, composed of stateful services, responsible for configuration (desired state), work flows (finite state machine tasks), grooming and scheduling logic. Xenon is also used by several teams building new products, services and features, within VMware.

For detailed information please refer to the wiki. Tutorials for each Xenon service patterns will be made available in the coming months. Various samples are under the dcp-samples directory.

A detailed list of pre-requisite tools can be found in the developer guide.

Once you have installed all the pre-requisites from the root of the repository execute the following command:

  mvn clean test

The above command will compile the code, run checkstyle and run unit-tests.

The team uses Eclipse or IntelliJ. Formatting style settings for both these editors can be found in the contrib folder.