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Diffstat (limited to 'docs/docbook/devdoc/printing.sgml')
| -rw-r--r-- | docs/docbook/devdoc/printing.sgml | 89 |
1 files changed, 80 insertions, 9 deletions
diff --git a/docs/docbook/devdoc/printing.sgml b/docs/docbook/devdoc/printing.sgml index 3cce7ab99c..1d4085bb88 100644 --- a/docs/docbook/devdoc/printing.sgml +++ b/docs/docbook/devdoc/printing.sgml @@ -60,14 +60,85 @@ 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) +C: Send a RFFPCN request with the previously obtained + handle with either (a) set of flags for change events + to monitor, or (b) a PRINTER_NOTIFY_OPTIONS structure + containing the event information to monitor. The windows + spooler has only been observed to use (b). +S: The opens a new TCP session to the client (thus requiring + all print clients to be CIFS servers as well) and sends + a ReplyOpenPrinter() request to the client. +C: The client responds with a printer handle that can be used to + send event notification messages. +S: The server replies success to the RFFPCN request. + +C: The windows spooler follows the RFFPCN with a RFNPCN + request to fetch the current values of all monitored + attributes. +S: The server replies with an array SPOOL_NOTIFY_INFO_DATA + structures (contained in a SPOOL_NOTIFY_INFO structure). + +C: If the change notification handle is ever released by the + client via a PCPCN request, the server sends a ReplyClosePrinter() + request back to the client first. However a request of this + nature from the client is often an indication that the previous + notification event was not marshalled correctly by the server + or a piece of data was wrong. +S: The server closes the internal change notification handle + (POLICY_HND) and does not send any further change notification + events to the client for that printer or job. + +The current list of notification events supported by Samba can be +found by examining the internal tables in srv_spoolss_nt.c + + * printer_notify_table[] + * job_notify_table[] + +When an event occurs that could be monitored, smbd sends a messages +to itself about the change. The list of events to be transmitted +are queued by the smbd process sending the message to prevent and +overload of TDB usage and the internal message is sent during smbd's +idle loop (refer to printing/notify.c and the functions +send_spoolss_notify2_msg() and print_notify_send_messages() ). + + +The decision of whether or not the change is to be sent to connected +clients is made by the routine which actually sends the notification. +( refer to srv_spoolss_nt.c:recieve_notify2_message() ). + +Because it possible to recieve a listing of multiple changes for +multiple printers the notification events must be split into +categories by the printer name. This makes it possible to group +multiple change events to be sent in a single RPC according to the +printer handle obtained via a ReplyOpenPrinter(). + +The actual change notification is performed using the RRPCN request +RPC. This packet contains + + * the printer handle registered with the client's spooler on + which the change occurred + * The change_low value which was sent as part of the last + RFNPCN request from the client + * The SPOOL_NOTIFY_INFO container with the event information + - the version and flags field are predefined and should not + be changed + - The count field is the number of entries in the + SPOOL_NOTIFY_INFO_DATA array + o The type defines whether or not this event is for a printer + or a print job + o The field is the flag identifying the event + o the notify_data union contains the new valuie of the attribute + o The enc_type defines the size of the structure for marshalling + and unmarshalling + o (a) the id must be 0 for a printer event on a printer handle. + (b) the id must be the job id for an event on a printer job + (c) the id must be the matching number of the printer index used + in the response packet to the RFNPCN when using a print server + handle for notification. Samba currently uses the snum of + the printer for this which can break if the list of services + has been modified since the notification handle was registered. + o The size is either (a) the string length in UNICODE for strings, + (b) the size in bytes of the security descriptor, or (c) 0 for + data values. - -* Back Channel -* Methods of sending an event -* Id numbers (print server handles, jobids, & printer handles ) -* event types ( jobs & printer attributes ) -* aggegating notifications - |