1. A method comprising: determining one or more events performed on a first data content object of a file, the one or more events being performed by a first user on a first client device using a data-content-object processing application, the file being stored in a data store, the first data content object being a defined portion less than all of the file; storing one or more event indications about the one or more events in a history buffer, each of the one or more event indications including event metadata indicating the one or more events performed by the first user on the first data content object; retrieving a notification threshold condition associated with a second user, wherein the notification threshold condition is based on a notification frequency determined by the second user, the notification threshold condition defining first criteria for determining which of the one or more event indications are relevant to the second user and second criteria for determining based on at least one of the one or more event indications being relevant to the second user whether to generate and send a notification to the second user, the first criteria defining that a particular event indication is relevant to the second user based on, at least in part, whether the second user has collaboratively worked with another user that has commented on the first data content object of the file, the second criteria defining whether to generate and send the notification to the second user based on, at least in part, second user preferences configurable by the second user and defining threshold quality of change to the first data content object before the generating and sending of the notification; using the first criteria to determine which of the one or more event indications are relevant to the second user; using the second criteria to determine whether the at least one of the one or more event indications being relevant to the second user satisfies the threshold quality of change to the first data content object; and if the second criteria is satisfied, generating and sending the notification for the second user.
1. A method comprising: determining one or more events performed on a first data content object of a file, the one or more events being performed by a first user on a first client device using a data-content-object processing application, the file being stored in a data store, the first data content object being a defined portion less than all of the file; storing one or more event indications about the one or more events in a history buffer, each of the one or more event indications including event metadata indicating the one or more events performed by the first user on the first data content object; retrieving a notification threshold condition associated with a second user, wherein the notification threshold condition is based on a notification frequency determined by the second user, the notification threshold condition defining first criteria for determining which of the one or more event indications are relevant to the second user and second criteria for determining based on at least one of the one or more event indications being relevant to the second user whether to generate and send a notification to the second user, the first criteria defining that a particular event indication is relevant to the second user based on, at least in part, whether the second user has collaboratively worked with another user that has commented on the first data content object of the file, the second criteria defining whether to generate and send the notification to the second user based on, at least in part, second user preferences configurable by the second user and defining threshold quality of change to the first data content object before the generating and sending of the notification; using the first criteria to determine which of the one or more event indications are relevant to the second user; using the second criteria to determine whether the at least one of the one or more event indications being relevant to the second user satisfies the threshold quality of change to the first data content object; and if the second criteria is satisfied, generating and sending the notification for the second user. 5. The method of claim 1 , wherein at least one of the one or more events includes reading, creating, modifying, removing, inserting, or moving content of the first data content object.