BO3-2: Some IPP Clients issues a zero length HTTP Post. The Client assumed
that this would force a challenge if security is enabled on the Printer.
The Client would have a problem if a subsequent print operation were
Proposed Resolution: The Client should use the IPP operation
"validate-job" to check if a job will be accepted. This operation will
cause the Printer to issue a challenge and check the print request before
sending the data. The IPP Client should also be able to handle a challenge
when issuing an IPP operation since there is no guarantee the connection has
not been torn down.
Furthermore, a Printer should accept an empty HTTP post and
issue a challenge based on the URL of the post.
Action Item: Bob Herriot: Some clients determined if a
Printer requires authentication by sending an
empty HTTP request. Some Printers treated this as an error.
was for clients to send a ValidateJob operation and by
inference to allow
Printers to reject empty HTTP requests.
I raised the issue about whether a Printer should perform
challenge based solely on the URL or whether it could react
an empty request than to a Validate-Job request.
I asked an HTTP expert and received the following
1) An HTTP server can have any policy.
This means that our decision is allowable.
2) It is best for a client if it can associate the URL
the authentication space.
This means that our decision could be better. That is,
require an IPP Printer to decide whether to issue an
challenge by examining the URL and nothing else, e.g.
receiving a request for a particular URL, gives the
challenge to an empty request as to a Validate-Job
This solution allows a client to use Validate-Job to request
a challenge as
we decided to allow. It also allows a client to use the
The important difference between our decision and what I am
that the Printer must perform an authentication challenge
consistently for a
URL regardless of the contents of the message body. This
rule make IPP
behavior consistent with good HTTP policy.
Xerox Architecture Center
Voice: (716) 265-8755
FAX: (716) 265-8792
US Mail: Peter Zehler
800 Phillips Rd.
Webster NY, 14580-9701
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