Taking Action

There are just a few fundamental actions. The rest are built from these as user-defined actions.

The following are the most commonly used basic actions are available in KRL:

send_directive(<expr>). This returns a directive with the name given by the expression <expr>. (Don't confuse action names, send_directive in this case, and directive names given as the required parameter to the action.) Optional parameters provided to send_directive are passed through to the options structure of the directive as name-value pairs. This action is the primary means of creating directive documents for endpoints. For example, the following action produces the directive document below it:

send_directive("say", {"something":"Hello World"})


{"directives":
 [{"options":{"something":"Hello World"},
   "name":"say",
   "meta":{
     "rule_name":"hello_world",
     "txn_id":"8FF45D92-7EDB-11DF-B34A-4BA9F4723EB4",
     "rid":"a16x66"
   }
  }
 ]
}

See the send_directive() documentation for more details.

http:post(<expr>). This action makes an HTTP POST to the URL given by <expr>. Any parameters in the optional qs map are added as name-value pairs in the query string of the URL. This action is useful for interacting with external Web services. For example, the following action makes an HTTP POST to the given URL, form-encoding q and sending it as the body of the POST:

http:post("http://google.com/search", qs = {"q":"hello"})

See the HTTP module documentation for more information.

event:send(<expr>). This action sends an event to another pico. The event channel of the other pico is specified in a map with the name "cid" (channel ID). The action also takes a domain and type for the event to send. You can specify event attributes using the optional with clause:

event:send({"cid": owner}, "fuse", event:type())
     with attrs = event:attrs();

For details about how this works, see the documentation for the event library.