Extensions

Extensions are SPARKL applications that provide the core functionalities of the SPARKL® Sequencing Engine. These applications can be used by referencing them in the markup of services. It is also possible to extend the core functionalities by adding optional extensions.

Table 1. Service provisioning with SPARKL extensions
Attribute value	Core or optional	Description
`sequencer`	Core extension	Services provisioned using the Sequencer extension can process transactions.
`expr`	Core extension	The Expressions extension supports the use of Erlang expressions in SPARKL.
`subr`	Core extension	The Subroutine extension supports subroutine transactions called by a caller operation. Note: The subroutine specification is defined on the caller and callee operations on the `svc_subr` service.
`REST`	Core extension	The REST extension lets users integrate external service implementations written in JavaScript or Python.

Extensions can be viewed, started and stopped in the Node Elements view of the Developer Console.