Determining update availability via set intersection over a sub-optimal pathway

A method for determining an update is available for an item installed at a client computer, the method comprising:

• determining a unique identifier for the item;
• assembling a first data structure by applying a many-to-one mapping function to the unique identifier for the item, wherein the first data structure inconclusively indicates that the update is available for the item;
• sending the first data structure in a first transmission;
• from the first data structure, determining the update may be available for the item installed at the client computer;
• responsive to determining the update may be available for the item installed at the client computer, in a second transmission, sending a second data structure comprising confirmation data for the item installed at the client computer, wherein the second data structure conclusively indicates that the update is available for the item;
• and
• via the confirmation data for the item installed at the client computer, confirming the update is available for the item installed at the client computer.

A method for determining software update availability for a client computer by sending software update availability information over a communications pathway, the method comprising:

• with a hashing function, hashing unique identifiers of available software updates to non-unique identifiers to generate a data structure inconclusively indicating the availability of at least one software update;
• sending the data structure over the communications pathway during a first transmission;
• after the first transmission, comparing the data structure to a list of upgrade candidates for the client computer to determine an update may be available for an upgrade candidate in the list, wherein the update is identified by a non-unique identifier associated with the update via the hash function;
• responsive to affirmatively determining an update may be available, during a second transmission over the communications pathway, sending a list of entries for a plurality of software updates associated with the non-unique identifier via the hash function;
• and
• consulting the entries to conclusively determine if a software update is available for the upgrade candidate.