Extensions are SPARKL applications that provide the core functionalities of the SPARKLĀ® 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.
phidget Optional extension The Phidget extension allows you to map Phidgets sensors, motors and interfaces to fields.

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