Volume Number: 13

Issue Number: 12

Column Tag: develop

LaserWriter 8.5.1: The Extended 'PAPA'

Resource

by Richard Blanchard, RBI Software Systems Inc., Ingrid Kelly, Apple Computer Inc.

and Chorng-Shyan Lin, RBI Software Systems Inc.

Overview

Starting with LaserWriter 8.5.1, in order to support different types of desktop

printers, the 'PAPA' -8192 resource has been extended from 103 to 1024 bytes long.

This TechNote discusses the additional bytes and in what way the LaserWriter 8.5.1

driver uses them.

Note: If your code relies on the size of the 'PAPA' resource, it may crash with

LaserWriter 8.5.1 unless you update it to support the extended 'PAPA' resource.

The 'PAPA' Resource

The new 'PAPA' looks just like an old style 'PAPA' at the front of the resource; that is,

the 'PAPA' resource begins with three packed Pascal strings representing the printer

name, the network type (usually LaserWriter), and the printer's zone. After these

strings comes the 4-byte network address.

The new extended 'PAPA' then adds desktop printer (DTP) data beginning at the 104th

byte in the resource. The data from bytes 104 to 1024 (1-based indices) is a series

of tagged blocks where each block contains a 4-byte tag, followed by a 2-byte length

value, and then the actual data. A series of these tagged blocks can reside in bytes 104

to 1024.

Tag Requirements

There are a few requirements for the tagged blocks that go into the extended 'PAPA.'

They are:

• The only required block in an extended 'PAPA' is the 'TAGS' tag which

gives the number of valid tag blocks in the extended resource. The 'TAGS' block

must be the first tag in the extended record and serves as a validity check.

• When the extended portion of the 'PAPA' contains multiple tag blocks, each

block is required to start on a word (16-bit) boundary. Thus, if a tag block

has an odd length, there should be a byte of padding before the start of the next

tag block.

• In order to limit the number of clients that need to understand the

extended 'PAPA' format, and to make it easier to change the format in the

future, the SettingsLib provides routines for creating and accessing the

extended 'PAPA.' Relying on the extended 'PAPA' format rather than using

SettingsLib is a bad idea. For more information on SettingsLib, please see

Apple's TechNote web site.

Tag Types

Tag: 'TAGS'

Value Size: sizeof(UInt16), 2 bytes

The value of the 'TAGS' block provides the number of valid tag blocks in the extended

print record including itself. The 'TAGS' block must be the first tag in the extended

print record; a valid extended print record must therefore begin with the byte

sequence: 0x5441 0x4753 0x0002.

Tag: 'TYPE'

Value Size: sizeof(OSType), 4 bytes

This tag is optional as its contents are redundant given the PAPA zone name string. If

this tag does exists, then its value must match, not literally but in meaning, the DTP

type implied by the zone string. Here are the zone string mappings to 'TYPE' values:

Zone Name 'Type' Definition

String tag value

=Hld 'Hold' Creates and holds spool files. The

spool files are never processed and

the

DTP is not connected to a real

printer.

=Fil* '=Fil' Creates PostScript or EPS files, is

not connected to a real printer.

=Cst* '=Cst' Creates a PostScript file and then

launches

an application to post-process the

file.

=LPR* '=LPR' Sends a PostScript job using the

LPR protocol.

=Ird* '=Ird' Sends a PostScript job over an irda,

infrared, channel.

Valid Zone string 'PAP' Uses the AppleTalk PAP protocol to

print

the job.

In the preceding mapping, the '*' in the zone name string is a wildcard which can be

replaced by zero or more characters of any value. The DTP Utility uses this part of the

zone name string to differentiate between DTP printers of the same type with the same

name located in different folders.

Beside the tag values 'Hold', '=Fil', '=Cst', '=LPR', '=Ird', and 'PAP ,' other tag values

may be added in the future for new DTP types.

Tag: 'TCP '

Value Size: variable size string

If the DTP printer type requires a TCP/IP network address, it is placed in the extended

PAPA using the 'TCP ' tag. The value of the tag block is the network address of the

printer either as a fully qualified network address, such as colorlaser.apple.com, or in

dot format, such as 204.188.109.151.

This tag is required for DTP printers of type '=LPR.' The length of the string is

determined from the block length.

Tag: 'Q'

Value Size: variable size string.

If a DTP can use a print queue name, as can LPR DTPs, then the print queue name is

placed in a tag value block of type 'Q .' The length of the string is determined from the

block length.

Summary of DTP type, zone names, and tags.

DTP Type PAPA Zone String Extended Data Tags

PAP Actual Zone Name 'TYPE' is 'PAP '

Hold " " " 'TYPE' is 'Hold'

Save to File =Fil* 'TYPE' is '=Fil'

Custom =Cst* 'TYPE' is '=Cst'

LPR =LPR* 'TYPE'is'=LPR'

'TCP'is printer's net

address

'Q'is optional and is the

name of

the print spooler.

InfraRed =Ird 'TYPE'is'=Ird'

Summary

This TechNote has documented the changes in the 'PAPA' resource in LaserWriter

8.5.1. Please beware if your application depends on the size of the 'PAPA' as it may no

longer work with LaserWriter 8.5.1.

Further Reference

• Apple's TechNote web site at

http://devworld.apple.com/dev/technotes.shtml.

Acknowledgements

Thanks to Leticia Alarc'n, John Blanchard and Paul Danbold

______________________________

Richard Blanchard has been programming LaserWriter 8 since its inception and

one day hopes to finish it. Working at RBI Software Systems, Inc. Richard, from day to

day, codes in C, C++, and Java and tries to draw a bead on the future of network

printing.

Ingrid Kelly works in Apple’s Developer Technical Support group. She was sad to see

the Blue Angels air show season end this year, but never fear, she is already counting

down the days until the start of next year’s air show season. 99...98...97...

Chorng-Shyan Lin is a Macintosh developer at RBI Software Systems, Inc. He can be

reached via email at lin@rbi.com.