This request will be stored in the relevant facilitator's knowledge base. When a manufacturer announces a new product, it will have a catalog agent send a message with the announcement and any changes to the advertisement of the agent to the facilitator. The facilitator will then send appropriate notifications to those parties who have expressed interest in this news. Notice that the facilitator notification scheme is symmetric. Catalog agents express interest in being given product data queries.
User agents express interest in being given product data announcements.
The same notification scheme is used for both types of activities. Operators of virtual catalogs have several alternative models for paying for their operation. The operator may take and process orders and use the markup on the transaction. Alternatively, the operator may make money merely by providing information. The operator may charge manufacturers, either a fixed fee or per referral.