METHOD OF HANDLING POSSIBLE "OUT-OF-ORDER" TRAPS FROM A PRINTER THAT IS SENDING BOTH PRINTER AND JOB TRAPS
Original Publication Date: 2000-Jun-01
Included in the Prior Art Database: 2003-Jun-19
Described is a method for handling SNMP traps (asynchronous notifications) that arrive out of order from a printer that is sending both printer and job traps. The problem is that SNMP (Simple Network Management Protocol) traps can arrive out of order--that is, a trap sent before another can actually arrive at the destination after it. In some cases, the second trap should be ignored (e.g. if the trap is reporting "page 3 printed" after the trap for "page 4 printed" has already been received and handled), but in other cases, the second trap needs to be handled (e.g. if the trap is reporting "cold start", it needs to be handled since the printer configuration might have changed due to the cold start). Below is an algorithm for determining which such out-of-order traps must be handled. This algorithm is based on a certain set of types of traps, but is easily extensible to other types as well. First, the timestamp of the last received trap of each type is kept track of. Then whenever it makes sense, handling of a "later" trap must take care of the handling of any implied earlier trap. For example, if a trap is received that is part of copy 4, but no trap saying that copy 3 was complete was received, the copy 4 trap handling must also do any required processing for the completion of copy 3--in this way, if the "copy 3 complete" trap comes in later, it can be discarded. Note also that traps that arrive with the same timestamp might also be out of order. This situation must be taken into account in the processing. In this embodiment, the following are the types of traps sent by the printer: printer traps (jam, out of paper, and so on), Cold Start, and job traps (Job Start(enumerated value 1), Sheet Complete(2), Copy Complete(3), Job Complete(4), Job Canceled(5), Job Aborted(6)).