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When submitting a
print job to a printer, the client provides the attributes
describing the characteristics of the print data, such as the
document name, and how the print data should be printed, such as
double-sided, five copies. If a print job consists of multiple
pieces of print data, different pieces might have different
processing instructions, such as 8 x 11 inch media for the first
document, and 11 x 17 inch media for another document.
Once the printer
starts processing the print job, additional information about the
job becomes available, which might include: the job state (such as
completed or queued) and the number of pages printed so far. These
pieces of information are also attributes. Attributes can also
describe the printer itself, such as: the printer name, the printer
location, and the number of jobs queued.
The Java Print
Service API defines these different kinds of attribute roles with
five subinterfaces of Attribute:
-
PrintRequestAttribute is used by an application to represents a
setting applied to an entire print job and to specify how the
entire print job should be printed.
- DocAttribute is
used by an application to specify a characteristic of a single
document and the print job settings to be applied to the
document.
- PrintJobAttribute
is used by a print service to report how a job is being printed.
These values will usually be identical the requested attribute
values. However, if the printer does not support the value of a
print request attribute then the corresponding print job attribute
contains a different value that is supported by the printer
-
PrintServiceAttribute is used by a print service to report the
status of the print service.
-
SupportedValuesAttribute is used by a print service o indicate the
range of values supported for a request attribute. For example, a
printer might support only a certain range of copies. When a print
service is queried for the supported range of copies, it returns
this information in a CopiesSupported object, which implements
SupportedValuesAttribute.
Many attributes can be
members of more than one role. For example, the Media attribute
belongs to the doc, print job, and print request roles because the
Media attribute can describe the paper size, the paper tray, or
paper type. In fact, most doc attributes are also request
attributes, and all request attributes are also job attributes.
The next section
describes how to collect attributes together into attribute sets,
which also have roles.
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