














		     XC-MISC Extension



			Version 1.1
		   X Consortium Standard
		 X Version 11, Release 6.8






		       Bob Scheifler
		      David P. Wiggins
		     X Consortium, Inc.









Copyright (C) 1994 X Consortium

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documenta-
tion files (the ``Software''), to deal in the Software with-
out restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to
whom the Software is furnished to do so, subject to the fol-
lowing conditions:

The above copyright notice and this permission notice shall
be included in all copies or substantial portions of the
Software.

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 PUR-
POSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE X CONSOR-
TIUM 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
OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of the X Con-
sortium 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.


























































1.  Overview

When an X client connects to an X server, it receives a
fixed range of resource IDs to use to identify the client's
resources inside the X server.	Xlib hands these out sequen-
tially as needed.  When it overruns the end of the range, an
IDChoice protocol error results.  Long running clients, or
clients that use resource IDs at a rapid rate, may encounter
this circumstance.  When it happens, there are usually many
resource IDs available, but Xlib doesn't know about them.

One approach to solving this problem would be to have Xlib
notice when a resource is freed and recycle its ID for
future use.  This strategy runs into difficulties because
sometimes freeing one resource causes others to be freed
(for example, when a window is destroyed, so are its chil-
dren).	To do a complete job, Xlib would have to maintain a
large amount of state that currently resides only in the
server (the entire window tree in the above example).  Even
if a less comprehensive strategy was adopted, such as recy-
cling only those IDs that Xlib can identify without main-
taining additional state, the additional bookkeeping at
resource creation and destruction time would likely intro-
duce unacceptable overhead.

To avoid the problems listed above, the server's complete
knowledge of all resource IDs in use by a client is lever-
aged.  This extension provides two ways for Xlib to query
the server for available resource IDs.	Xlib can use these
extension requests behind the scenes when it has exhausted
its current pool of resource IDs.

2.  Requests

XCMiscGetVersion

     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_ver-
sion indicate what version of the protocol the client wants
the server to implement.  The server version numbers
returned indicate the protocol this extension actually sup-
ports.	This might not equal the version sent by the client.
An implementation can (but need not) support more than one
version simultaneously.  The server_major_version and the
server_minor_version are a mechanism to support future revi-
sions of the XC-MISC protocol which may be necessary.  In
general, the major version would increment for incompatible



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		      XC-MISC Extension


changes, and the minor version would increment for small,
upward-compatible changes.  Servers that support the proto-
col defined in this document will return a server_major_ver-
sion of one (1), and a server_minor_version of one (1).

XCMiscGetXIDRange

   =>

     start_id: XID
     count: CARD32

This request returns a range of available resource IDs for
the client issuing the request.  start_id is the first ID in
the range.  count is the number of IDs in the range.  The
returned range may or may not be the largest possible range.

XCMiscGetXIDList

     count: CARD32

   =>

     ids: LISTofXID

This request returns the a list of individual resource IDs
in ids.  count is the number of resource IDs requested.  The
number returned may be smaller than the number requested.

3.  Events and Errors

No new events or errors are defined by this extension.

4.  Encoding

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

The name of this extension is ``XC-MISC''.


XCMiscGetVersion
  1  CARD8		 opcode
  1  0			 XC-MISC opcode
  2  2			 request length
  2  CARD16		 client_major_version
  2  CARD16		 client_minor_version


 =>
  1  1			 Reply
  1			 unused
  2  CARD16		 sequence number
  4  0			 length



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		      XC-MISC Extension


  2  CARD16		 server_major_version
  2  CARD16		 server_minor_version
  20			 unused



XCMiscGetXIDRange
  1  CARD8		 opcode
  1  1			 XC-MISC opcode
  2  1			 request length


 =>
  1  1			 Reply
  1			 unused
  2  CARD16		 sequence number
  4  0			 length
  4  XID		 start_id
  4  CARD32		 count
  16			 unused



XCMiscGetXIDList
  1  CARD8		 opcode
  1  2			 XC-MISC opcode
  2  2			 request length
  4  CARD32		 count


 =>
  1  1			 Reply
  1			 unused
  2  CARD16		 sequence number
  4  CARD32		 length
  4  CARD32		 number of XIDs in ids
  20			 unused
  4n LISTofXID		 ids



















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