Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!vsi1!daver!athsys!jim
From: jim@athsys.uucp (Jim Becker)
Newsgroups: comp.windows.x
Subject: Request for Object-Oriented extension to XEvents (long)
Message-ID: <161@tityus.UUCP>
Date: 17 Oct 88 18:19:56 GMT
Organization: Athena Systems, Inc., Sunnyvale, CA
Lines: 91

Intro:

    Before making this request, I want to state that I understand
    the  current  pressure  upon  the MIT staff to get R3 out and
    free of problems as quickly as possible. The request  that  I
    am making is assumed NOT to be part of the next release of X,
    but would be a worthwhile addition to the X  package  in  the
    future.  I  believe  that  I am aware of the ramifications of
    backward-compatability and such, but believe that this future
    enhancement of X could prove very useful for improving appli-
    cation event processing throughput.  I also assume that  this
    request  has  been  thought  of and made, although I have not
    seen in come across the wire.

    This request seems rather simple to introduce to the package,
    and  may  already  be  in there somewhere, although I haven't
    discovered it as of yet.  It would greatly help me, and  lots
    of  others,  that are developing UIMS type packages for the X
    windows standard. As my clients' needs get more complex,  not
    having  this  capability  will simply slow down my ability to
    minimize response time.

Background & Request:

    There are a number of user interface packages and Widget sets
    that  are  being  created for the X windows platform. Most of
    these are adopting an object oriented approach to  the  task,
    OO being the latest buzzword in the industry.

    The interface system managing the user events currently reads
    the  event  stream,  interprets  the context of the event and
    dispatches the appropriate software routines to do  the  han-
    dling.  For  each event, the logic must determine the mapping
    of the "window" field of the XEvent structure to the internal
    data  structures  associated with the window.  Once this con-
    nection is made the software routines are dispatched.

    Mapping of the XEvent window XID to  the  cooresponding  data
    structures  and logic currently must be done within the logic
    of the interface handling portion of the client program. This
    normally involves some sort of tablular or linked-list lookup
    within the resources of the client.  Herein lies the overhead
    of the event processing throughput.

    More complex interfaces represent more  windows  and  lookup,
    hence  more  slowdown in determining the correct object of an
    event. In certain instances this has led  to  re-writting  of
    the  server or lookup algorithms to optimize this task. (I am
    thinking of what I know of the DECwindows approach).

    This lookup is currently within the server, to determine  the
    XID  of  the  event  being  dispatched, as well as within the
    client, to map the XID to the client data internals. It would
    be  nice  to eliminate the redundancy from the client side of
    the logic.

    Elimination of this lookup logic is trivial.  If  there  were
    the  ability  for  the client to associate a pointer with the
    XID window resource this pointer could be returned along with
    the XEvent structure. The pointer would be a generic "UserDa-
    ta" field, and it was up to the client to define  and  inter-
    pret  this  field.  In  an  object-oriented world the pointer
    would point to the object of the window, whatever data format
    that was defined as being.

    This capability would eliminate the need for additional logic
    and   overhead  of  the  client  process.  It  would  improve
    throughput of X and make it a cleaner/leaner machine to util-
    ize.  And  it is pretty easy to add (no flames, please). With
    the continuing complexity and demands of the software  world,
    this shortcut may help ease the creation of programs and more
    easily define application interfaces.


Simple Statement of Request:

    I tend to be a little verbose, what I am requesting is simply
    a  new  "UserData"  field  that is settable for an XID window
    resource. The specified "UserData" would  be  returned  as  a
    field  in the XEvent structure for use by the client program.
    It would be a 32 bit field that was defined and understood by
    the  client  only,  with  the  server  just passing the value
    around.


Thanks for listening to yet another request. I hope this one  can
make it in at some time, I think it would greatly help in the fu-
ture speed and complexity of X products.


-Jim Becker		sun!athsys!jim