Subject: IPP> Re: MOD - ISSUE: How to determine the document-uri schemes supported?

From: Tom Hastings <[email-masked]>
Date: Fri, 12 Sep 1997 11:00:32 PDT

At 09:26 09/11/97 PDT, Jay Martin wrote:
>Considering we have just declared a "Functionality Freeze", is this
>something we really need to do?

I think it is more of a "plugging a hole" than new fuctionality
and its only a Printer description attribute.  See below to see if 
you agree.

>
>Can you cite some examples/scenarios in which *not* having this
>new attribute would make life very difficult (or impossible) to
>implement?

As I understand the spec and agreements, we've agreed that validation
of a document-uri cannot be part of a Validate operation, since the
Validate operation is identical to a Print-Job operation which cannot 
have a document-uri attribute.  So there is no way for a client to know 
what scheme to try for a Print-URI or Send-URI scheme, except to try it,
in the Print-URI or Send-URI operation.

Then we have also been debating whether a Printer has to validate the
document-uri or not on the Print-URI or Send-URI operation.  We've agreed
that the standard will NOT require the Printer to validate the URI.
So the user may NOT even get an error back on the Print-URI or the Send-URI
operation that the scheme is not supported (though maybe we should
add such an error and at least recommend that a Printer at least validate
that the URI scheme is supported, if it doesn't validate the entire
URI.)

Finally, I suspect that it will be an end-user, rather than a program,
that will be supplying URIs in Print-URI and Send-URI operations.  The
end-user knows about document xxx and wants to submit it by reference
to Printer yyy, so that the end-user should be able to find out which 
schemes are supported.

We already have a notification-schemes-supported, so that
"document-uri-schemes-supported" is very similar.

On the other hand, those more familiar with HTTP servers can tell us
whether most HTTP servers support most URI schemes that an end-user might
need, such as HTTP:, FTP:, and HTTPS:

Alternatively, we could recommend a list of URI schemes for a Printer
to support.  Or would that get out of date?  And require a lot discussion
and debate?

So adding a "document-uri-schemes-supported" Printer attribute seemed
an easy solution.  The complete proposed spec is given below.

Tom

>
>	...jay
>
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>
>
>Tom Hastings wrote:
>> 
>> In the vein of "plugging holes":
>> 
>> ISSUE:  How can a client determine which uri schemes the Printer supports
>> for use in the "document-uri" attribute in the Print-URI and Send-URI
>> operations?
>> 
>> How about adding a printer description attribute:
>> 
>> document-uri-schemes-supported (1setOf uriScheme)
>> 
>> This attribte specifies the URI schemes that the Printer supports for use in
>> the "document-uri" attribute in the Print-URI and Send-URI operations.
>> If the Printer does not support either of these operations, the
>> "document-uri-schemes-supported" attribute SHALL not be supported.
>
>