1. A method comprising: delegating a task associated with an identified portion of a first data content object to a particular user; determining one or more events performed on content within the identified portion of the first data content object, the one or more events being performed by a first user using a data-content-object processing application; storing one or more event indications identifying the one or more events in a history buffer, at least one of the one or more event indications including metadata indicating first-user interaction with the content within the identified portion of the first data content object; retrieving a notification threshold condition associated with the particular user, the notification threshold condition defining criteria for determining which of the one or more event indications are relevant to the particular user and for determining based on the one or more event indications relevant to the particular user whether to send a notification to the particular user, at least one of the criteria requiring that the relevancy of at least one of the one or more events be determined based on an interaction with the identified portion of the first data content object by the particular user, wherein the interaction is that the particular user previously commented on the identified portion of the first data content object; using the criteria to determine which of the one or more event indications in the history buffer are relevant to the particular user where the relevant historical event indications are determined based on which event indications in the history buffer correspond to the identified portion of the first data object delegated to the particular user; using the criteria to determine whether the one or more event indications relevant to the particular user satisfies the notification threshold condition; and when the notification threshold condition is satisfied, generating the notification for the particular user.
1. A method comprising: delegating a task associated with an identified portion of a first data content object to a particular user; determining one or more events performed on content within the identified portion of the first data content object, the one or more events being performed by a first user using a data-content-object processing application; storing one or more event indications identifying the one or more events in a history buffer, at least one of the one or more event indications including metadata indicating first-user interaction with the content within the identified portion of the first data content object; retrieving a notification threshold condition associated with the particular user, the notification threshold condition defining criteria for determining which of the one or more event indications are relevant to the particular user and for determining based on the one or more event indications relevant to the particular user whether to send a notification to the particular user, at least one of the criteria requiring that the relevancy of at least one of the one or more events be determined based on an interaction with the identified portion of the first data content object by the particular user, wherein the interaction is that the particular user previously commented on the identified portion of the first data content object; using the criteria to determine which of the one or more event indications in the history buffer are relevant to the particular user where the relevant historical event indications are determined based on which event indications in the history buffer correspond to the identified portion of the first data object delegated to the particular user; using the criteria to determine whether the one or more event indications relevant to the particular user satisfies the notification threshold condition; and when the notification threshold condition is satisfied, generating the notification for the particular user. 6. The method of claim 1 , wherein at least one of the one or more events includes creating, removing, uploading, downloading or sharing the first data content.