19. A system comprising: a communicator module configured to receive a connection request from a seller application that is customizable by configuration information that includes a hierarchal product category structure for generating a listing for a product for sale using, the seller application executing on a client machine; an upgrade control module; and a processor configured by the upgrade control module to determine that the seller application has not been customized by a current version of the configuration information, the upgrade control module configuring the processor to: transmit the a current version of the configuration information the seller application; receive, from the seller application, a product listing request and a configuration confirmation, the configuration confirmation indicating the seller application on the client machine has been configured using the current version of the configuration information to include the hierarchal product category structure; and generate a product listing using the product listing request.
19. A system comprising: a communicator module configured to receive a connection request from a seller application that is customizable by configuration information that includes a hierarchal product category structure for generating a listing for a product for sale using, the seller application executing on a client machine; an upgrade control module; and a processor configured by the upgrade control module to determine that the seller application has not been customized by a current version of the configuration information, the upgrade control module configuring the processor to: transmit the a current version of the configuration information the seller application; receive, from the seller application, a product listing request and a configuration confirmation, the configuration confirmation indicating the seller application on the client machine has been configured using the current version of the configuration information to include the hierarchal product category structure; and generate a product listing using the product listing request. 22. The system of claim 19 , wherein: the upgrade control module configures the processor to transmit the configuration information that includes the hierarchal product category structure, the configuration information configured to enable a user of the seller application to classify a listing created by the user for publication by a network-based facility.