Distributed Query Language

piping

list * | filter @unit='kwh' | subscribe $value

• every query method is based on the result of left pipe
• the first method will always be based on the root node of the broker

methods

list

• syntax: list {path}
• input: array of node
• output: array of node
• distributed: yes

{path}:

• * means match any nodes
• ? means match one node

exmaples

 list /a/b/c
 list /?/a?/?b/c
 list /a/b/c*

subscribe

• syntax: subscribe {expression1}, {expression2}, {expression3} .....
• input: array of node
• output: array of records (with path and the record id)
• distributed: yes

Examples

 subscribe $path
 subscribe $value
 subscribe child.value

filter

• syntax: filter {condition}
• input: array of nodes or array of records
• output: same type as input
• distributed: yes

examples

 filter $unit="F"
 filter @icon!=null

invoke

invoke actions

set

set config/attribute/value

remove

remove config/attribute

window

waiting for changes and doing rollup