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diff --git a/XpConfig/README b/XpConfig/README new file mode 100644 index 000000000..d7447815d --- /dev/null +++ b/XpConfig/README @@ -0,0 +1,318 @@ + + -------------------------------------- + The X Print Service - The Basics + -------------------------------------- + +Index + - 1.0 X Print Service Overview + + - 2.0 How the X Print Service Works + + - 3.0 Using the X Print Service + - 3.1 X Print Server Configuration + - 3.2 Starting the X Print Service + - 3.3 Configuring the environment + - 3.4 General End-User Sequence + + +1.0 X Print Service Overview +============================= + +The "X Print Service" technology allows X rendering to devices such as +printers and fax. Most of the service is available in the X11 +technology stack as Xp, with the remainder in the CDE technology stack +as DtPrint. Modifications have also been made to the Motif technology +stack to support Xp and DtPrint. + +The Xp portion consists of: + * Xp Extension for the X-Server (included in the X-Server Xprt) + * Xp Extension API for the client side (libXp) + * PCL ddx driver that converts core X to native PCL + * Postscript ddx driver that converts core X to native Postscript + * Raster ddx driver that generates xwd rasters which can be + converted to PCL or Postscript rasters + +The DtPrint portion consists of: + * A collection of print GUIs (libDtPrint) + * A Print Dialog Manager that can assist a client in + setting printing options (dtpdm, dtpdmd) + +From an X clients perspective, it can attach to one of two nearly +identical X-Servers, a "Video" X-Server, and a "Print" X-Server +which has the additional Xp capability but otherwise looks and +behaves the same. + + + +2.0 How the X Print Service Works +================================== + +The X Print Service expands on the traditional X-Server and Xlib world +in four ways. + +1. Most obvious is the use of "print ddx drivers" instead of + "video ddx drivers". While a video ddx driver modifies pixels + in a video frame buffer, a print ddx driver generates "page + description language (PDL)" output such as PCL or Postscript. + + Once a print ddx driver generates PDL output, it can be sent to + a spooler such as lp(1) or retrieved by the client. + + Though not currently done, a single X-Server can support both + print and video ddx drivers. + +2. Since printers support "paged" output, unlike video, a portion + of the Xp Extension supports APIs to delineate printed output. + For example, XpStartPage and XpEndPage tell the X-Server where + a physical page starts and ends in an otherwise continuous + stream of X rendering primitives. Likewise, XpStartJob and + XpEndJob determine when a collection of pages starts and ends. + XpEndJob typically causes the generated PDL to be submitted to + a spooler, such as lp(1). + +3. Since printers have extensive capabilities, another portion of + the Xp Extension supports APIs to manipulate "print contexts". + + Once a printer is selected using the Xp Extension API, a print + context to represent it can be created. A print context + embodies the printer selected - it contains the printer's + default capabilities, selectable range of capabilities, + printer state, and generated output. Some "attributes" within + the print context can be modified by the user, and the + X-Server and print ddx driver will react accordingly. For + example, the attribute "content-orientation" can be set to + "landscape" or "portrait". + +4. Since printers can have "built in" fonts, the Xp Extension in + the X-Server works with the print ddx drivers to make + available (for printing only) additional fonts on a per print + context basis. + + When a print context is created and set for a given printer, + the X font calls may be able to access additional printer + fonts. To do this (typically), the X-Server must have access + to "printer metric files" (.pmf) that describe at minimum the + metrics of the built in fonts. + + + +3.0 Using the X Print Service +============================== + +There are three tasks to start the X Print Service: 1) configuring the +X Print Server, 2) starting the X Print Service, 3) configuring the user +session so that clients can find the running X Print Service. + +The tasks are described in detail below. + + +3.1 X Print Server Configuration +--------------------------------- + +The X Print Server (Xprt) can read a number of configuration files which +control its behavior and support for printers. Each vendor platform has +a default location for this information. Xprt can also read the +environment variable XPCONFIGDIR to locate alternate configuration +directories. Common settings include: + + * export XPCONFIGDIR=/X11/lib/X11/XpConfig/ + + * export XPCONFIGDIR=/proj/x11/xc/programs/Xserver/XpConfig/ + +Xprt has many built-in defaults, and lacking any configuration files, +will immediately try to support all printers visible via lpstat(1). + +In order of importance for configuration by a system administrator, the +configuration files for a "C" locale are as follows. + + ${XPCONFIGDIR}/C/print/Xprinters + + `Xprinters' is the top most configuration file. It tells + Xprt which specific printer names (e.g. mylaser) should + be supported, and whether lpstat(1) or other commands + should be used to automatically supplement the list of + printers. + + ${XPCONFIGDIR}/C/print/attributes/printer + + The `printer' file maps printer names to model + configurations (see `model-config' below). For example, + "mylaser" could be mapped to a "HPDJ1600C", and all other + arbitrary printers could be mapped to a default, such as + "HPLJ4SI". When depending on lpstat(1) in the Xprinters + file, setting up defaults in `printer' becomes all the + more important. + + ${XPCONFIGDIR}/C/print/attributes/document + + The `document' file specifies the initial document values + for any print jobs. For example, which paper tray to + use, what default resolution, etc. + + ${XPCONFIGDIR}/C/print/attributes/job + + The `job' file specifies the initial job values for any + print jobs. For example, "notification-profile" can be + set so that when a print job is successfully sent to a + printer, e-mail is sent to the user. + + ${XPCONFIGDIR}/C/print/models/HPDJ1600C/model-config + ${XPCONFIGDIR}/C/print/models/HPDJ1600C/fonts/fonts.dir + ${XPCONFIGDIR}/C/print/models/HPDJ1600C/fonts/9nb00051.pmf + ${XPCONFIGDIR}/C/print/models/HPDJ1600C/fonts/9nb00093.pmf + + The `model-config' file has attributes that describe the + printer model's capabilities and default settings. + Printer model fonts may also be present. The model-config + file also identifies the print ddx driver to be used. + + For each printer model supported, a complete hierarchy of + files should exist. In most cases, these files do not + need to be modified. + + ${XPCONFIGDIR}/C/print/ddx-config/raster/pcl + ${XPCONFIGDIR}/C/print/ddx-config/raster/postscript + + The print ddx drivers can have highly specific + configuration files to control their behavior. In most + cases, these files do not need to be modified. + + +3.2 Starting the X Print Service +--------------------------------- + +The summary checklist for starting the X Print Service is as follows: + +1. Choose an execution model for the X Print Service. The X + Print Service can be run on a per-user session basis, per + machine basis, or can be run on a few machines globally + available to a number of users. + +2. If print jobs are to be submitted to a spooler (almost always + the case), make sure all needed printers are available to the + spooler subsystem (most often lp(1)) on the same machine + running the X Print Service. + +3. Configure the X Print Server. See ``X Print Server + Configuration''. + +4. Depending on #1, start the X Print Server process "Xprt", and + then the Print Dialog Manager Daemon process "dtpdmd" at the + appropriate times. + +The details are described below. + +Because the X Print Service is based on X, it can be easily distributed. +The most significant factors in which execution model to choose will be +driven by: + + * how many printers will be accessable through the printer + subsystem on any given machine. A system administrator may + choose to cluster printers on a few given machines, or + scatter them across an organization and possibly make + extensive use of remote spoolers to make them globally + available. + + * how many machines will need a copy of the X Print Server + configuration files. The files have been architected so + that one super-set version of them can be maintained and + distributed (e.g. via NFS), and a per-machine or per-user + version of the `Xprinters' is all that is needed to have the + appropriate information in them utilized or ignored. + + * how many users can demand services from a given X Print + Service. + +With the above in mind, some obvious execution models include: + + * Global - in this model, the system administrator is choosing + to run the X Print Service on a *few* select machines with + appropriate printers configured, and allow clients access to + the global resource. This can centralize the administration + of printers and configuration files, but may have to be + monitored for performance loading. + + Startup would likely be done by boot-up scripts. + + * Per-machine - every machine with potential X Print Service + users would run the service. Printer and configuration file + administration is decentralized, and usage would be limited + to the users on the machine. + + Startup would likely be done by boot-up scripts. + + * Per-user session - every user would run an entire X Print + Service for themselves. In the future, the Video X Server + normally started may contain Print X Server capability, so + this model becomes very natural. + + Startup would likely be done at session login or by + launching actions or processes manually once the user + logs in. Note: the dtpdmd must be started after Xprt. + +Starting of the processes is straight forward. In strict order: + + [machineA] % Xprt [-XpFile <Xprinters file>] [:dispNum] & + + Note that Xprt will look for configuration files in either + a default location or where XPCONFIGDIR points. + + -XpFile specifies an alternate `Xprinters' file, rather + than the default one or `${XPCONFIGDIR}/C/print/Xprinters'. + + [machineA] % dtpdmd -d machineA[:dispNum] [-l /tmp/dtpdmd.log] & + + The dtpdmd will maintain an X-Selection on the X-Server, + and will start dtpdm's as required to service requests. + +In all but the per-user session model, the machine running the dtpdmd +(thus dtpdm's) will need display authorization to the users video +display. + + + +3.3 Configuring the environment +-------------------------------- + +Once a X Print Server and dtpdmd have been started -- many of them +in some cases -- clients will need to find and use them. There are +two mechanisms that allow clients to discover X Print Servers and +printers. + + * "X Print Specifier" - assuming usage of the DtPrint print + dialogs, the following notation is understood: + + printer_name@machine[:dispNum] + + For example: + + colorlj7@printhub:2 + + In the above example, the X Print Server running at `printhub:2' + is assumed to support the printer named `colorlj7'. + + * "XPSERVERLIST" - assuming usage of the DtPrint print dialogs, + the environment variable "XPSERVERLIST" can contain a list + of X Print Servers. For example: + + XPSERVERLIST="printhub:2 printhub:3 otherdept:0" + + Then in the dialogs, only a printer name needs to be entered. + The dialog will then search the X Print Servers in XPSERVERLIST + for a server than supports the printer, and then establish + contact. + +3.4 General End-User Sequence +------------------------------ + +From most CDEnext applications, printing is accomplished by bringing +down the <File> menu and selecting <Print...>. This will result in +the DtPrintSetupBox dialog, which will request the name of a printer, +and offer limited capability to configure print options (e.g. number +of copies). If the user wishes, they can select <Setup...>, which +will start a dtpdm capable of modifying additional print options. +Finally, the user should select <Print>. + + + +$Xorg: README,v 1.3 2000/08/17 19:48:02 cpqbld Exp $ |