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4.1 Client/Service Organization > 4.1.4 Trusted Intermediaries - Pg. 163

4.1 Client/Service Organization 163 4.1.3 Multiple Clients and Services In the examples so far, we have seen one client and one service, but the client/service model is much more flexible: One service can work for multiple clients. A printer service might work for many clients so that the cost of maintaining the printer can be shared. A file service might store files for many clients so that the information in the files can be shared. One client can use several services, as in the sewage pump controller (see Figure 4.5), which uses both a pump service and a sensor service. A single module can take on the roles of both client and service. A printer ser- vice might temporarily store documents on a file service until the printer is ready to print. In this case, the print service functions as a service for printing requests, but it is also a client of the file service. 4.1.4 trusted Intermediaries A single service that has multiple clients brings up another technique for enforcing