JET is a framework which means all the features ties together that enables JUNOS to be more open and programmable.

There are four big components of JET
1. Python: Python 2.7.8 is supported on all JUNOS devices. By using Python users can develop and execute Python scripts on JUNOS.

2. JSON: JSON is popular data exchange program because of it’s simplicity, light weight and rich native support in several programming languages. Most of the python programmers use JSON as data exchange program. With this help now JUNOS operational show commands can display data in JSON format also along with XML format. JUNOS configuration can be provided directly in JSON format which can help programmer to write code in python and push configuration on box without having worry of XML.

3. Fast Programmatic Configuration Database: It is fast programmatic configuration database used by JUNOS and gives access to controller’s applications which are pushing fast state changes onto JUNOS. SDN applications can make the changes at very high rate with 1000 of configuration changes per second with no configuration validation. The onus of configuration validation will be taken care by the external SDN controllers and applications.