meta
The meta
library provides information about the running ruleset. The following are available (notice that these are values, not functions):
meta:eci - the event channel identifier on which the current event was raised
meta:host - the public DNS name of the machine running the engine, including port number. Does not include the trailing "/". ex. http://localhost:8080 You may configure this value when starting your pico engine. See the developer tips page to see why and how.
meta:inEvent - Boolean value
true
if the engine is evaluating an event for this pico,false
otherwisemeta:inQuery - Boolean value
true
if the engine is evaluating a query for this pico,false
otherwisemeta:picoId - the ID of the currently running pico
meta:rid - the ruleset ID of the currently running ruleset
meta:ruleName - the name of the rule currently being evaluated
meta:rulesetURI - the URL from which the currently running ruleset was registered/installed
meta:txnId - the transaction ID for the current evaluation. This is mostly useful for debugging or as a correlation identifier
meta:rulesetConfig - the configuration Map given when the ruleset was installed in the pico
Wrangler and Meta
Some of the data in the meta block is also available through Wrangler:
wrangler:rulesetMeta(meta:rid){"author"}
- the author from the meta section of the current ruleset
wrangler:rulesetMeta(
meta:rid){"description"} - the description
from the meta section of the current ruleset
wrangler:rulesetMeta(
meta:rid){"name"} - the name
from the meta section of the current ruleset
Not Supported
The following are not yet available:
meta:callingRID() - returns the RID of the calling ruleset if running in a module, or the current ruleset ID otherwise.
meta:callingVersion() - returns the version of the calling ruleset if running in a module, or the current ruleset version otherwise.
meta:errorCount() - returns the number of errors for current rule execution. Reset to 0 for each new rule execution.
meta:inModule() - returns a Boolean value indicating whether the current code is running in a module.
meta:moduleRID() - returns the RID of the module if running in a module, or the current ruleset ID otherwise.
meta:moduleVersion() - returns the version of the module if running in a module, or the current ruleset version otherwise.
meta:version() - returns the version of the currently running ruleset.
Note, in the case of meta:moduleRID()
, meta:moduleVersion()
, and meta:inModule()
, care has been taken to preserve static behavior. So, for example, if you do the following, you should get the result you expect based on static function semantics:
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ruleset my_module {
...
global {
myRid = function() { meta:rid }
}
}
ruleset use_my_module {
meta {
use module my_module
}
global {
x = my_module:myRid();
// x = my_module, not use_my_module
}
}