Server : Client :: Dealer : Customer
One of the most important structures for networked computing is the relationship between server and client. A server provides computing resources at the request of other parties, called clients. These other parties send their requests to the server in the form of a data transmission called a request. The server acts on the request in some way by applying its computing resources (processor cycles, electricity, water) and returns the results to the client in the form of another data transmission. The distinguishing feature of a server is availability, namely the fact that the server is listening and responsive at the time that the client makes its request. The unavailable server is not a server.
One of the most important structures for market exchange is the relationship between dealer and customer. A dealer provides balance sheet resources at the request of other parties, called customers. These other parties send their requests to the dealer in the form of a data transmission called an order. The dealer acts on the order in some way using its balance sheet (by buying from customers who wish to sell or selling to customers who wish to buy) and returns the results to the client in the form of a settlement procedure. The distinguishing feature of a dealer is liquidity, namely the fact that the dealer has posted transaction prices and is willing to transact at the time the customer places its order. The illiquid dealer is not a dealer.