The problem occurs when the IPP-to-LPD mapper receives a Cancel-Job.
The operation contains the job-uri only, but the LPD remove-jobs
command requires a printer-name as the target and the job-number as
a parameter. The mapping of the job-uri to a job-number is a separate
difficult issue.
Because the job-uri is opaque, the mapper cannot determine
the corresponding printer from it. I see two possible solutions:
o add a mandatory job description attribute called "printer-uri" which
references the printer containing the job.
o make all commands have the printer-uri as the target with
the job-uri as a parameter for operations that currently go to a job.
This eliminates the need to map from a job to a printer because
all operations include the printer-uri from which jobs can be obtained.