!=
!= Samba Printing Internals
!= 
!= Author : Gerald Carter <jerry@samba.org>
!=
!===================================================================

The purpose of this document is to provide some insight into
Samba's printing functionality and also to describe the semantics
of certain features of Windows client printing.

Print Queue TDB's
------------------

* matching lanman jobids, spoolss jobids, & lpd jobids
* why ?
* caching time


ChangeID & Client Caching of Printer Information
------------------------------------------------

[To be filled in later]


Windows NT/2K Printer Change Notify
-----------------------------------

When working with Windows NT+ clients, it is possible for a
print server to use RPC to send asynchronous change notification
events to clients for certain printer and print job attributes.
This can be useful when the client needs to know that a new
job has been added to the queue for a given printer or that the
driver for a printer has been changed.  Note that this is done 
entirely orthogonal to cache updates based on a new ChangeID for 
a printer object.

The basic set of RPC's used to implement change notification are

  * RemoteFindFirstPrinterChangeNotifyEx ( RFFPCN )
  * RemoteFindNextPrinterChangeNotifyEx ( RFNPCN )
  * FindClosePrinterChangeNotify( FCPCN )
  * ReplyOpenPrinter
  * ReplyClosePrinter
  * RouteRefreshPrinterChangeNotify ( RRPCN )

One additional RPC is available to a server, but is never used by the
Windows spooler service:

  * RouteReplyPrinter()

The opnum for all of these RPC's are defined in include/rpc_spoolss.h

Windows NT print servers use a bizarre method of sending print
notification event to clients.  The process of registering a new change
notification handle is as follows.  The 'C' is for client and the
'S' is for server.  All error conditions have been eliminated.

C:	Obtain handle to printer or to the printer
	server via the standard OpenPrinterEx() call.
S:	Respond with a valid handle to object

C:	Send a RFFPCN request with the previously obtained 
	handle and either (a)



* Back Channel
* Methods of sending an event
* Id numbers (print server handles, jobids, & printer handles )
* event types ( jobs & printer attributes )
* aggegating notifications