Application Group Extension to the X Protocol

X Consortium Standard

Kaleb S. KEITHLEY

   X Consortium, Inc
   <kaleb@x.org>

   X Version 11, Release 7.7

   Version 1.0

   Copyright © 1996 X Consortium, Inc.

   All Rights Reserved.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE
   FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   CONNECTION WITH THE SOFTWARE OR THE USE OF OR OTHER DEALINGS IN
   THE SOFTWARE.

   Except as contained in this notice, the name of the X
   Consortium shall not be used in advertising or otherwise to
   promote the sale, use or other dealings in this Software
   without prior written authorization from the X Consortium.

   X Window System is a trademark of The OpenGroup.

   27 September 1996

   The Application Group Extension to the X protocol is intended
   to provide a framework to allow more than one program to manage
   X applications on the desktop. The initial use of this
   extension will be to insert or embed the windows of X programs
   into the windows of another program, such as a web browser.
   This extension is not intended to address larger embedding
   issues that, for example, OpenDoc does, such as shared menu
   bars, etc.
     __________________________________________________________

   Table of Contents

   Purpose and Goals
   Overview of the protocol.
   Requests
   Changes to Existing Requests

        MapWindow
        ConfigureWindow
        CreateWindow
        ChangeWindowAttributes

   Changes to Existing Events

        MapRequest
        ConfigureRequest

   Errors

        AppGroupQueryVersion
        AppGroupCreate
        AppGroupDestroy
        AppGroupGetAttr
        AppGroupQuery
        AppGroupCreateAssociation
        AppGroupDestroyAssociation

   Encoding
   Library API
   A. System Window Encodings

Purpose and Goals

   The Application Group Extension to the X protocol is intended
   to provide a framework to allow more than one program to manage
   X applications on the desktop. The initial use of this
   extension will be to insert or embed the windows of X programs
   into the windows of another program, such as a web browser.
   This extension is not intended to address larger embedding
   issues that, for example, OpenDoc does, such as shared menu
   bars, etc. Using X programs on the World Wide Web allows for
   greater control of the presentation and takes advantage of the
   existing body of X programs rather than re-implement them in
   another language. In addition it allows the embedding of non-X
   programs into web browsers by using third party products like
   Wabi, MAE, and WinCenter. ^[1]

Overview of the protocol.

   This extension introduces the concept of an Application Group.
   An Application Group is a set of one or more applications that
   are primarily managed by a special application known as the
   Application Group Leader, which, for example, might be a web
   browser. The primary purpose of Application Groups is to
   provide a means of sharing the Substructure-Redirect attribute
   of the root window between the window manager and one or more
   Application Group Leaders.

   To join an Application Group an application must present the
   proper authorization during the connection setup.
   Authorizations are generated by the X server at the request of
   an Application Group Leader, and are then stored for the
   application to use to establish its connection to the X server.
   To generate an authorization the Application Group Leader sends
   a request to the server naming the Application Group to which
   the authorization will be bound, and any applications that
   connect using that authorization will automatically become part
   of the associated Application Group. The protocol to generate
   an authorization is defined in the Security Extension
   specification.

   As a member of an Application Group, when an application
   creates and maps a window as a child of the root window, the
   MapRequest and ConfigureRequest events are delivered to the
   Application Group Leader instead of the window manager. The
   Application Group Leader may then reparent the window into its
   own window hierarchy; or reissue the map request, in which case
   the window comes under the control of the window manager.

Requests

   AppGroupQueryVersion
   client_major_version: CARD16
   client_minor_version: CARD16
   =>
   server_major_version: CARD16
   server_minor_version: CARD16

   If supplied, the client_major_version and client_minor_version
   indicate what version of the protocol the application wants the
   server to implement. The server version numbers returned
   indicate the version of the protocol the X server actually
   supports. This may not match the versions requested by the
   application. An implementation may (but need not) support more
   than one version simultaneously. The server_major_version and
   server_minor_version numbers are a mechanism to support any
   future revisions of the Application Group extension protocol
   which may be necessary. In general, the major version would
   increment for incompatible changes, and the minor version would
   increment for small, upward-compatible changes. X servers that
   support the protocol defined in this document will return a
   server_major_version of 1 and a server_minor_version of 0.

   AppGroupCreate
   app_group: APPGROUP
   value_mask: BITMASK
   value_list: LISTofVALUE

   This request creates an Application Group using app_group as
   the Application Group ID.


   The value_mask and value_list specify attributes of the
   Application Group that are to be explicitly initialized. The
   attributes, their types, and the default values are:
   Attribute        Type     Default
   app_group_leader Bool     True
   single_screen    Bool     True
   default_root     Window   None
   root_visual      VisualID None
   default_colormap Colormap None
   black_pixel      Pixel    0
   white_pixel      Pixel    0

   If the single_screen attribute is True then the number of video
   screens returned to a program in the Application Group in the
   connection setup message is one, irrespective of how many video
   screens the server actually has. If a server supports both
   video and print screens, then all print screens will always be
   returned. If single_screen is specified as True then the
   connection setup message will contain only the information
   about the video screen which has default_root as its root
   window, plus any print screens.

Note

   The intent is to allow an embedding manager to ensure that it
   will be able to reparent any top-level windows that Application
   Group members create. By hiding the fact that there are other
   screens it can be reasonably assured that applications will
   only create top-level windows on the same screen that it itself
   appears on. An embedding manager should take care not to supply
   an invalid display, e.g. :0.1, to a program that will be in an
   Application Group where the single_screen attribute is True.

   If single_screen is set to True default_root specifies which
   screen will be returned as screen zero in the connection setup
   message for applications in the Application Group. If set to
   None, then the real screen zero is used, otherwise the screen
   which has default_root as its root window will be used.

   If single_screen is set to True the root_visual and
   default_colormap attributes may be used to over-ride the
   default values that are returned in the connection setup
   information returned to new programs in the Application Group.
   If None is specified for root_visual or default_colormap then
   the normal default values for the screen (possibly spedified by
   default_root) are used, otherwise the specified values are
   used. If root_visual and/or default_colormap are specified they
   must be valid, i.e. root_visual must be a visual type available
   on the screen, and the colormap, if specified, must be a valid
   colormap for the visual that is used.

   IF single_screen is set to True and default_colormap is not
   specified as None, the black_pixel and white_pixel attributes
   must be specified, and they will over-ride the default values
   that are returned in the connection setup returned to new
   programs in the Application Group. If default_colormap is
   specified as None and black_pixel and/or white_pixel are
   specified, they will be ignored.

   The app_group_leader attribute is used to identify the
   Application Group Leader program for the app_group. By
   specifying True the server will identify the program making the
   request as the Application Group Leader for the application
   group. The Application Group Leader receives MapRequest and
   ConfigureRequest events from the server when an attempt is made
   to map or configure top-level windows of a program in an
   Application Group, instead of being sent to a window manager
   that has selected SubstructureRedirect events on the root
   window. The parent window field in these events will contain
   the Application Group ID.

   AppGroupDestroy

   app_group: APPGROUP

   This request destroys the app_group. If the app_group_leader
   attribute for the app_group is True, then any applications in
   the Application Group that are still connected will be killed
   as if a KillClient request had been received for that
   application.

Note

   If the application that created a non-embedded Application
   Group exits, and therefore any Authorizations to be cancelled,
   and any applications that attempt to open new connections to
   the X server using one of those Authorizations will be unable
   to do so.

   AppGroupGetAttr
   >app_group: APPGROUP
   =>
   LISTofVALUE

   This request returns the application group attributes for
   app_group.

   AppGroupQuery
   resource: XID
   =>
   app_group: APPGROUP

   This request returns the Application Group ID of the
   application that created resource or None if that application
   is not associated with any Application Group. The resource
   value may be the resource base of the application.

   AppGroupCreateAssociation
   window: WINDOW
   window_type: CARD32
   system_window: LISTofCARD8

   This request associates window with system_window. The
   window_type indicates the native window system of the
   application making the request. For non-X window_types both the
   embedding manager and the server must be executing on the same
   host. When system_window is Microsoft Windows or OS/2
   Presentation Manager, the system_window is an HWND; when the
   native window system is Macintosh, the system_window is a
   WindowPtr and a Rect. The window may be used for any X request
   that takes a Window.

   AppGroupDestroyAssociation
   window: WINDOW

   This request destroys the association created with
   AppGroupCreateAssociation. The window is destroyed. The
   system_window that was specified in the
   AppGroupCreateAssociation request is not affected.

Changes to Existing Requests

MapWindow

   If the override-redirect attribute of the window is False and
   if the window is a child of a root window and if the window
   belongs to an application that is in an application group and
   if some other application is the application group leader for
   that group, then a MapRequest event is generated and the window
   remains unmapped. Otherwise, the core protocol semantics apply.

ConfigureWindow

   If the override-redirect attribute of the window is False and
   if the window is a child of a root window and if the window
   belongs to an application that is in an application group and
   if some other application is the application group leader for
   that group, then a ConfigureRequest event is generated and the
   window remains unchanged. Otherwise, the core protocol
   semantics apply.

CreateWindow

   When a program in an Application Group creates a window that is
   a child of a root window and specifies CopyFromParent for the
   Visual, if the single_screen attribute is True and the
   root_visual attribute is set to something other than None, then
   the window will be created using the Application Group's
   root_visual, otherwise core protocol semantics apply.

   When a program in an Application Group creates a window that is
   a child of a root window and specifies CopyFromParent for the
   Colormap, if the single_screen attribute is True, the
   default_colormap attribute is set to something other than None,
   and the window's Visual is the same as the Application Group's
   root_visual attribute, then the window will be created using
   the Application Group's default_colormap, otherwise core
   protocol semantics apply.

ChangeWindowAttributes

   When a program in an Application Group changes the attributes
   of a window that is a child of a root window and specifies
   CopyFromParent for the Colormap, if the single_screen attribute
   is True, the default_colormap attribute is set to something
   other than None, and the window's Visual is the same as the
   Application Group's root_visual attribute, then the window will
   be created using the Application Group's default_colormap,
   otherwise core protocol semantics apply.

Changes to Existing Events

   When the top-level window of an application that is a member of
   an Application Group is the target of a MapWindow or
   ConfigureWindow request, if there is an Application Group
   Leader then MapRequest and ConfigureRequest events are
   automatically delivered to it, otherwise the core protocol
   semantics apply, i.e. they are delivered to the client, if any,
   that has SubstructureRedirect set in its root-window event
   mask, e.g. the window manager.

Note

   The Application Group Leader must not select SubstructuRedirect
   events on a root window as doing so would result in a core
   protocol error; only one client is permitted to do so, and that
   is usually the window manager.

MapRequest

   When a MapWindow request is received for a window whose
   override-redirect attribut is set to False and whose parent is
   the root window and the window belongs to an application that
   is in an application group and there is an application group
   leader for the group, then this event is delivered to the
   Application Group Leader with the parent field in the event set
   to the AppGroup ID. Otherwise the core protocol semantics
   apply.

ConfigureRequest

   When a ConfigureWindow request is received for a window whose
   override-redirect attribut is set to False and whose parent is
   the root window and the window belongs to an application that
   is in an application group and there is an application group
   leader for the group, then this event is delivered to the
   Application Group Leader with the parent field in the event set
   to the AppGroup ID. Otherwise the core protocol semantics
   apply.

Errors

AppGroupQueryVersion

   There are no errors for AppGroupQueryVersion.

AppGroupCreate

   A Window error is returned if default_root is specified and is
   not a valid root window..

   A Color error is returned default_colormap is specified but
   default_colormap is not a valid colormap for the screen of
   default_root.

   A Match error is returned if root_visual and default_colormap
   are both specified, but

   default_colormap's visual is not root_visual.

   A Match error is returned if root_visual does not exist for the
   screen of the default_root.

AppGroupDestroy

   An AppGroup error is returned if app_group is not a valid
   Application Group.

   An Access error is returned if an untrusted application
   attempts to destroy an Application Group created by a trusted
   application.

AppGroupGetAttr

   An AppGroup error is returned if app_group is not a valid
   Application Group.

   An Access error is returned if an untrusted application
   attempts to get the attributes of an Application Group created
   by a trusted application.

AppGroupQuery

   An Access error is returned if an untrusted application
   attempts to query the Application Group of a trusted
   application.

AppGroupCreateAssociation

   A Match error is returned if the X server does not support the
   window_type.

   An Access error may be returned if the X server only supports
   the window_type on the local host and the program making the
   request is on a non-local host.

   A Window error may be returned for system-specific errors
   related to system_window, e.g. system_window does not represent
   a valid native window.

AppGroupDestroyAssociation

   A Window error is returned if window was not specified in a
   previous AppGroupCreateAssociation request.

Encoding

   Please refer to the X11 Protocol encoding document as this
   document uses conventions established there.

   The name of this extension is XC-APPGROUP
AppGroupQueryVersion
      1      CARD8        opcode
      1      0            XC-APPGROUP opcode
      2      3            length
      2      CARD16       client_major_version
      2      CARD16       client_minor_version
=>
      1      1            Reply
      1                   unused
      2      CARD16       sequence_number
      4      0            length
      2      CARD16       server_major_version
      2      CARD16       server_minor_version
      20                  unused

AppGroupCreate
      1      CARD8            opcode
      1      1                XC-APPGROUP opcode
      2      8+n              length
      4      XID              app_group
      4      BITMASK          attrib_mask
             #x00000001   app_group_leader
             #x00000002   single_screen
             #0x0000004   default_root
             #x00000008   root_visual
             #x00000010   default_colormap
             #x00000020   black_pixel
             #x00000040   white_pixel
      n      LISTofVALUE      value-list
VALUEs
      4      BOOL             app_group_leader
      4      BOOL             single_screen
      4      WINDOW           default_root
      4      VISUALID         root_visual
      4      COLORMAP         default_colormap
      4      CARD32           black_pixel
      4      CARD32           white_pixel

AppGroupDestroy
      1      CARD8            opcode
      1      2                XC-APPGROUP opcode
      2      2                length
      4      XID              app_group

AAppGroupGetAttr
      1      CARD8            opcode
      1      4                XC-APPGROUP opcode
      2      2                length
      4      XID              app_group
=>
      1      1                Reply
      1                       unused
      2      CARD16           sequence_number
      4      0                length
      4      WINDOW           default_root
      4      VISUALID         root_visual
      4      COLORMAP         default_colormap
      4      CARD32           black_pixel
      4      CARD32           whte_pixel
      1      BOOL             single_screen
      1      BOOL             app_group_leader
      2                       unused

AppGroupQuery
      1      CARD8            opcode
      1      5                XC-APPGROUP opcode
      2      2                length
      4      XID              resource
=>
      1      1                Reply
      1                       unused
      2      CARD16           sequence_number
      4      0                length
      4      XID              app_group
      20                      unused

AppGroupCreateAssoc
      1      CARD8            opcode
      1      6                XC-APPGROUP opcode
      2      n                length
      4      WINDOW           window
      2      CARD16           window_type
             #0      X11
             #1      Macintosh
             #2      Win32, OS/2 PM 2.x
             #3      Win16, OS/2 PM 1.x
      2      n                system_window_len
      n      LISTofCARD8      system_window

AppGroupDestroyAssoc
      1      CARD8            opcode
      1      7                XC-APPGROUP opcode
      2      2                length
      4      WINDOW           window

Library API

   Status XagQueryVersion ( xkb, keycode) /* macro */
   Display dpy;
   int * major_version_return;
   int * minor_version_return;

   XagQueryVersion sets major_version_return and
   minor_version_return to the major and minor Application Group
   protocol version supported by the server. If the Xag library is
   compatible with the version returned by the server it returns
   non-zero. If dpy does not support the Application Group
   extension, or if the server and library protocol versions are
   incompatible, or if there was an error during communication
   with the server, it returns zero. No other Xag functions may be
   called before this function. If a program violates this rule,
   the effects of all subsequent Xag calls that it makes are
   undefined.

Note

   An embedding manager in, e.g. a Personal Computer Web Browser,
   will need to open a connection to the Personal Computer X
   server by calling XOpenDisplay() before using the Application
   Group extension.

   An embedding manager such as a web browser that intends to
   embed programs in an Application Group should create the
   Application Group with XagCreateEmbeddedApplicationGroup.
   Status XagCreateEmbeddedApplicationGroup(
   Display* dpy,
   VisualID root_visual,
   Colormap default_colormap,
   unsigned long black_pixel,
   unsigned long white_pixel,
   XAppGroup* app_group_return);

   XagCreateEmbeddedApplicationGroup creates an Application Group
   for an embedding manager with the attributes specified. It also
   sets the default_root attribute to DefaultRoot(dpy,
   DefaultsScreen(dpy)) and the single_screen and app_group_leader
   attributes to True. It returns the Application Group ID in
   app_group_return.

   You can create an Application Group without intending to do
   embedding. One reason for doing this is to give a group of
   clients their own font-path.

Note

   A special font-path can be created by creating an Application
   Group, getting an Authorization using
   XSecurityGenerateAuthorization, and then running `xset fp+ <new
   font path>' as a member of the Application Group. Font-path
   elements added in this way will be "private" to the Application
   Group.
   Status XagCreateNonembeddedApplicationGroup(
   Display* dpy,
   XAppGroup* app_group_return);

   An Application Group created with
   XagCreateNonembeddedApplicationGroup will have the
   default_root, root_visual, and default_colormap attributes all
   set to None; the single_screen and app_group_leader attributes
   are set to False, and the black_pixel and white_pixel
   attributes are not used since the default_colormap attribute is
   None.

   To destroy an Application Group use XagDestroyApplicationGroup.
   Status XagDestroyApplicationGroup(
   Display* dpy,
   XAppGroup app_group);

   The Application Group specified by app_group is destroyed. If
   the Application Group was created using
   XagCreateEmbeddingApplicationGroup, i.e. and therefore the
   app_group_leader attribute is True, all programs that are
   members of the Application Group are killed as if a KillClient
   request had been issued.

   To retrieve the attributes of an Application Group use
   XagGetApplicationGroupAttributes.
   Status XagGetApplicationGroupAttributes(
   Display* dpy,
   XAppGroup app_group,
   ...);

   XagGetApplicationGroupAttributes is a varargs function that
   retrieves the Application Group's attributes specified in the
   vararg parameter list.

   The attributes that may be specified are: XagNappGroupLeader,
   XagNsingleScreen, XagNdefaultRoot, XagNrootVisual,
   XagNdefaultColormap, XagNblackPixel, and XagNwhitePixel; which
   correspond to app_group_leader, single_screen, default_root,
   root_visual, default_colormap, black_pixel, and white_pixel
   respectively. See AppGroupCreate in Section 3 for a description
   of each attribute.

   The types for each of the parameters are pointers to the
   following:

         single_screen          Bool
         default_root           Window
         root_visual            VisualID
         default_colormap       Colormap
         black_pixel            unsigned long
         white_pixel            unsigned long
         app_group_leader       Bool
Example:
      ...
      Boolean app_group_leader, single_screen;
      Window default_root;
      VisualID root_visual;
      Colormap default_colormap;
      Pixel black_pixel, white_pixel;
      ...
      status = XagGetApplicationGroupAttributes(dpy, app_group,
            XagNappGroupLeader, &app_group_leader,
            XagNsingleScreen, &single_screen,
            XagNdefault_root, &default_root,
            XagNrootVisual, &root_visual,
            XagNdefaultColormap, &default_colormap,
            XagNblackPixel, &black_pixel,
            XagNwhitePixel, &white_pixel,
            NULL);
      ...

   To determine which Application Group a resource (such as a
   window) belongs to, use XagQueryApplicationGroup.
   Status XagQueryApplicationGroup(
   Display* dpy,
   XID resource,
   XAppGroup* app_group_return);

   The Application Group is returned in app_group_return, if the
   resource is not in any Application Group then app_group_return
   will be set to None.

   To associate an X Window ID with a system-specific window ID,
   such as a HWND or a WindowPtr, use XagCreateAssociation.
   Status XagCreateAssociation(
   Display* dpy,
   Window* window_return,
   void* system_window);

   The window_ret may be used as the target for a ReparentWindow
   request.

Note

   Because XReparentWindow is not constrained in the same way that
   Win32's SetParent and the Macintosh are, there is no reason to
   call XagCreateAssociation in an X-based embedding manager. As
   such if XagCreateAssociation is called in a native X program,
   the window_return will be the same as the system_window, and
   the implementation may even elect to not generate any protocol.

   To create an association on the Macintosh:
      struct {
          WindowPtr win;
          Rect rect;
      } system_window;
      system_window.win = win_ptr;
      system_window.rect.top = system_window.rect.left = 20;
      system_window.rect.bottom = 180;
      system_window.rect.right = 380;

      status = XagCreateAssociation (dpy, &window, (void*)&system_window
);

   To create an association using a Win16, Win32, or OS/2 PM:
      HWND system_window;
      status = XagCreateAssociation (dpy, &window, (void*)&system_window
);

   To destroy the association created with XagCreateAssociation
   use XagDestroyAssociation.
   Status XagDestroyAssociation(
   Display* dpy,
   Window window);

   After calling XagDestroyAssociation the window may no longer be
   used to reparent windows with XReparentWindow.

Note

   Like XagCreateAssociation, if the native window system is X11
   the implementation may elect to not generate any protocol as a
   result of this function call in order to avoid unintentionally
   destroying the the system_window that was specified in the
   prior XagCreateAssociation call.

A. System Window Encodings

   The AppGroupCreateAssoc request has the following possible
   variations:

   AppGroupCreateAssoc (X11)
         1      CARD8            opcode
         1      6                XC-APPGROUP opcode
         2      n                length
         4      WINDOW           window
         2      0                window_type
         2      4                system_window_len
         4      WINDOW           Window

   AppGroupCreateAssoc (Macintosh)
         1      CARD8            opcode
         1      6                XC-APPGROUP opcode
         2      n                length
         4      WINDOW           window
         2      1                window_type
         2      12               system_window_len
         4      CARD32           WindowPtr
         2      INT16            Rect.top
         2      INT16            Rect.left
         2      INT16            Rect.bottom
         2      INT16            Rect.right

   AppGroupCreateAssoc (Win32)
         1      CARD8            opcode
         1      6                XC-APPGROUP opcode
         2      n                length
         4      WINDOW           window
         2      2                window_type
         2      4                system_window_len
         4      CARD32           HWND

   AppGroupCreateAssoc (Win16)
         1      CARD8            opcode
         1      6                XC-APPGROUP opcode
         2      n                length
         4      WINDOW           window
         2      3                window_type
         2      4                system_window_len
         2      CARD16           HWND offset
         2      CARD16           HWND segment
   __________________________________________________________

   ^[1] Wabi is a trademark of Sun Microsystems, Inc. MAE is a
   trademark of Apple Computer, Inc. WinCenter is a trademark of
   Network Computing Devices, Inc.
