script

An embedded tremor script is created with a special syntax that deviates from the operator creation. For a full reference see the section on tremor-query embedded-scripts.

The tremor script runtime allows to modify events or their metadata. To learn more about Tremor Script please see the related section.

The script operator allows to modify the events metadata (via $), and the script local state which persists across single events. state can be initialized with a state section in the scrtipt definition.

in addition to the script section, that is executed when an event arrives on the in port, the script operator allows to define multiple other sections with script from <port> that get executed when an event arrives on <port> all sections share the same state allowing to decuple control and dataflow.

Inputs:

• in - the main script section
• script from <port> is executed when data arrives at the port <port>

Outputs:

• out (default output used with emit)
• error - channel for runtime errors
• <anything else> used when emit event => "<anything else>"

Examples:

# definition
define script rt
script
  emit
end;

define script add
state
    state = 1
script from cfg
    # update the summand to a new value
    let state = event;
    drop
script
    emit event + state
end;

select event from in into add;
select event from cfg into add/cfg;
select event from add into out;