A social network system (or other type of hosting system) is described herein which allows different types of applications to interact with the common resources of the system via respective application-specific channels. Through an application-specific channel, a user may obtain a filtered set of content items (e.g., posts) and notifications that pertain to a particular application with which the user is currently interacting. But the user may also obtain items and notifications that do not necessarily have an affiliation with the particular application. The social network system may maintain a single identity for each user across all application channels hosted by the system.