A system, comprising an intermediate aggregation layer communicatively coupled between multiple instances of a messaging application, each such instance associated with an individual computer system, and multiple internet-based services, each associated with a unique application programming interface (API) and data layer, the aggregation layer providing a common schema for references to content objects with which the messaging applications are conversant and translations between the common schema and disparate schemas for references to content objects hosted in the data layers of the different internet-based services.