Abstract: A facility for assessing availability of an item for purchase from a merchant using a model of the availability of the item is described. The facility receives asynchronous messages identifying changes in the merchant's inventory for the item that affects the availability of the item for purchase from the merchant. For each received asynchronous message, the facility updates the model to reflect the changes in the merchant's inventory identified in the message. The facility then evaluates the state of the model in order to assess availability of the item for purchase from the merchant.

Abstract: A facility for processing a request for information about a specified item is described. The facility receives the request from an originator. In response to receiving the request, the facility generates a response to the request that contains information about the specified item. The facility also determines a current level of availability of the specified item, and, based upon this determined level of availability, determines, for each of a number of ordering actions, whether the ordering action is currently available for the specified item. For each ordering action determined to be currently available for the specified item, the facility augments the generated response by adding a control for performing the ordering action. The facility sends the augmented response to the originator of the request.

Abstract: A facility for determining availability status for item groups each containing one or more items is described. For each item whose availability status changes, for each item group containing the item, the facility adds the item group to a list of item groups if the item group is not already present in the list. The facility periodically removes a plurality of item groups from the list. For each item group it removes from the list, the facility determines an availability status for the item group based upon availability statuses of items contained in the group.

Abstract: A facility for analyzing ordering trends for an item is described. Based upon an historical ordering activity for the item, the facility projects future ordering activity for the item. The facility compares the future ordering activity projected for the item to inventory in the item. Based upon this comparison, the facility determines when future ordering activity is expected to exhaust inventory in the item.

Abstract: A facility for assessing availability of an item for purchase from a merchant using a model of the availability of the item is described. The facility receives asynchronous messages identifying changes in the merchant's inventory for the item that affects the availability of the item for purchase from the merchant. For each received asynchronous message, the facility updates the model to reflect the changes in the merchant's inventory identified in the message. The facility then evaluates the state of the model in order to assess availability of the item for purchase from the merchant.

Abstract: A facility for managing ownership of units of an item is described. The facility defines a commingling zone. For units of the item that are outside the commingling zone, the facility attributes ownership among a plurality of owners individually to each of the units. For units of the item that are inside the commingling zone, the facility attributes ownership among the plurality of owners to particular numbers of the units without attributing ownership individually to each of the units. The facility includes a method for reconciling ownership of units in the event of any discovered innacuracies.

Abstract: A facility for managing ownership of units of an item is described. The facility defines a commingling zone. For units of the item that are outside the commingling zone, the facility attributes ownership among a plurality of owners individually to each of the units. For units of the item that are inside the commingling zone, the facility attributes ownership among the plurality of owners to particular numbers of the units without attributing ownership individually to each of the units. The facility includes a method for reconciling ownership of units in the event of any discovered inaccuracies.

Abstract: A facility for determining availability status for item groups each containing one or more items is described. For each item whose availability status changes, for each item group containing the item, the facility adds the item group to a list of item groups if the item group is not already present in the list. The facility periodically removes a plurality of item groups from the list. For each item group it removes from the list, the facility determines an availability status for the item group based upon availability statuses of items contained in the group.