According to some implementations of the present disclosure, a method that is executed by a processing system is described. The method includes receiving an ad request, determining a context category structure based on the ad request, and identifying one or more app-specific rules based on the category defined in the context category. The method further includes, for each app-specific rule: determining whether the identified entities in the context category structure are received by the template defined in the app-specific rule; generating a function identifier based on the set of identified entities and the template when the identified entities are received by the template defined in the app-specific rule; and determining a score for each of the generated function identifiers. The method includes selecting one or more of the generated function IDs based on the respective scores of the function IDs and generating an advertisement object corresponding to the function ID.