Peter,
First, an "impression" is the image (possibly many print-stream pages in
different configurations) imposed onto a single side of a media sheet.
The "job-impressions-supported" (rangeOfInteger(0:MAX)) is a Printer
Description attribute which indicates the minimum and maximum number of
impressions (sides of a sheet) for a job that a Printer will accept in a Job
Creation operation. So if the client supplies the number of impressions in
the Job Creation operation, the Printer MUST validate that the supplied
value is in range. Presumably, a vendor would populate the Printer's
job-impressions-supported attribute, either with 'no-value' or with 0:MAX.
Then an administrator could limit the size of jobs to some smaller number,
say 100 impressions. Also an administrator might want to limit small jobs
on a high end printer, and so could set the lower limit to some number
greater than 0.
Here are the definitions of "job-impressions" operation attribute,
"job-impressions" Job Description attribute and the
"job-impressions-supported" Printer Description attribute:
"job-impressions" (integer(0:MAX)):
The client OPTIONALLY supplies this attribute. The Printer object
OPTIONALLY supports this attribute and the "job-impressions-supported"
attribute (see section 4.4.34). The client supplied "job-impressions"
operation attribute identifies the total size in number of impressions of
the document(s) being submitted (see section 4.3.17.2 for the complete
semantics).
See last paragraph under "job-k-octets".
4.3.17.2 job-impressions (integer(0:MAX))
This attribute specifies the total size in number of impressions of the
document(s) being submitted (see the definition of impression in section
12.2.5).
As with "job-k-octets", this value MUST NOT include the multiplicative
factors contributed by the number of copies specified by the "copies"
attribute, independent of whether the device can process multiple copies
without making multiple passes over the job or document data and independent
of whether the output is collated or not. Thus the value is independent of
the implementation and reflects the size of the document(s) measured in
impressions independent of the number of copies.
As with "job-k-octets", this value MUST also not include the multiplicative
factor due to a copies instruction embedded in the document data. If the
document data actually includes replications of the document data, this
value will include such replication. In other words, this value is always
the number of impressions in the source document data, rather than a measure
of the number of impressions to be produced by the job.
4.4.34 job-impressions-supported (rangeOfInteger(0:MAX))
This Printer attribute specifies the upper and lower bounds for the number
of impressions per job. The supported values are used to validate the client
supplied "job-impressions" operation attributes in create requests. The
corresponding job description attribute "job-impressions" is defined in
section 4.3.17.2.
Does that help?
Tom Hastings
-----Original Message-----
From: Peter Du [mailto:PeterDu at pek.destiny.com.cn]
Sent: Friday, July 06, 2001 02:51
To: 'Hastings, Tom N'
Subject: how to understand "impression"
Tom,
I am interested in IPP. it is a good "new body", there are have two
attributes in rfc2911.txt. "job-impression-supported" and
"compression-supported". I know compression tell us which way client use
when he create two operation ------send-document and print-job-----. but I
cannot know how to understand "job-impression-supported". can you help me?
thanks.
Best regard
Peter Du