A method of processing an interactive service at a receiver, the method comprising: receiving uncompressed audio content or uncompressed video content from an external decoding unit; extracting identifiers of frames from the received content and submitting requests having the identifiers to a server periodically; receiving a time base trigger from the server in response to one of the requests when an identifier corresponding to a new segment is detected; obtaining an application parameter table associated with the new segment by using information in the time base trigger; receiving an activation trigger from the server whenever an event is due to be activated, the activation trigger setting a time of a specific activation of a specific event; and providing the interactive service for the content by using the activation trigger, wherein the application parameter table includes a plurality of application elements including metadata of corresponding applications and app IDs uniquely identifying each of the corresponding applications, and characterized in that each of the application elements includes a plurality of event elements including metadata of corresponding events associated with an application and event IDs uniquely identifying each of the corresponding events within a scope of each of the application elements, and wherein the activation trigger includes a first value and a second value, the first value referencing one of the app IDs of an application element representing an application targeted by the specific event, and the second value referencing one of the event IDs of an event element representing the specific event within the referenced application element. receiving uncompressed audio content or uncompressed video content from an external decoding unit; extracting identifiers of frames from the received content and submitting requests having the identifiers to a server periodically; receiving a time base trigger from the server in response to one of the requests when an identifier corresponding to a new segment is detected; obtaining an application parameter table associated with the new segment by using information in the time base trigger; receiving an activation trigger from the server whenever an event is due to be activated, the activation trigger setting a time of a specific activation of a specific event; and providing the interactive service for the content by using the activation trigger, wherein the application parameter table includes a plurality of application elements including metadata of corresponding applications and app IDs uniquely identifying each of the corresponding applications, and characterized in that each of the application elements includes a plurality of event elements including metadata of corresponding events associated with an application and event IDs uniquely identifying each of the corresponding events within a scope of each of the application elements, and wherein the activation trigger includes a first value and a second value, the first value referencing one of the app IDs of an application element representing an application targeted by the specific event, and the second value referencing one of the event IDs of an event element representing the specific event within the referenced application element.