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In the EnvisionWare system, a library patron ”say, Sandra ”creates a document on a library's personal computer. She uses the Print command to submit the document for printing and then walks over to a release station to release the print job to the printer. A printing client on the personal computer and a release station client both communicate with a central server. The central server uses a database to store user and print job information. From Sandra's viewpoint, the system works as outlined in the following procedure. Incorporated into this activity flow are the message interactions that occur at designated points. The client sends the named message to the server and the server responds with the given message.
If an operation fails, FailMessage is returned as the response. The client can retry the operation or inform the user of the failure. Both the printing computer and the release station have a graphical user interface (GUI) associated with them. The GUI is a thin layer on top of the messaging system. |
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