Use Rule designer to create a webservice Rule, and add Palette items to perform the task(s) you would like to Rule to perform. It will require authentication by default. This can be changed by going to the Edit function, but this is not advisable. Then go to User Preferences, and in the API tab click on Generate API Key. Copy the value of API Key and suffix this to http://[URL]/rule/json/[rule_name]?api_key=