NAME

       multiplexer - One-to-many communication with sockets.

SYNOPSIS

       package require Tcl  8.2

       package require logger

       package require multiplexer  ?0.2?

       ::multiplexer::create

       ${multiplexer_instance}::Init port

       ${multiplexer_instance}::Config key value

       ${multiplexer_instance}::AddFilter cmdprefix

       cmdprefix data chan clientaddress clientport

       ${multiplexer_instance}::AddAccessFilter cmdprefix

       cmdprefix chan clientaddress clientport

       ${multiplexer_instance}::AddExitFilter cmdprefix

       cmdprefix chan clientaddress clientport

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DESCRIPTION

       The  multiplexer package provides a generic system for one-to-many communication utilizing
       sockets.  For example, think of a chat system where one user sends a message which is then
       broadcast to all the other connected users.

       It is possible to have different multiplexers running concurrently.

       ::multiplexer::create
              The create command creates a new multiplexer 'instance'.  For example:

              set mp [::multiplexer::create]

              This instance can then be manipulated like so:

              ${mp}::Init 35100

       ${multiplexer_instance}::Init port
              This starts the multiplexer listening on the specified port.

       ${multiplexer_instance}::Config key value
              Use  Config to configure the multiplexer instance.  Configuration options currently
              include:

              sendtoorigin
                     A boolean flag. If true, the sender will receive a copy of the sent message.
                     Defaults to false.

              debuglevel
                     Sets the debug level to use for the multiplexer instance, according to those
                     specified  by  the  logger  package  (debug,  info,  notice,  warn,   error,
                     critical).

       ${multiplexer_instance}::AddFilter cmdprefix
              Command to add a filter for data that passes through the multiplexer instance.  The
              registered cmdprefix is called when data arrives  at  a  multiplexer  instance.  If
              there  is  more  than  one  filter  command registered at the instance they will be
              called in the order of registristation, and each filter will get the result of  the
              preceding  filter  as  its argument. The first filter gets the incoming data as its
              argument. The result returned by  the  last  filter  is  the  data  which  will  be
              broadcast to all clients of the multiplexer instance.  The command prefix is called
              as

              cmdprefix data chan clientaddress clientport
                     Takes the incoming data, modifies it, and returns that as  its  result.  The
                     last  three  arguments  contain  information about the client which sent the
                     data to filter: The channel connecting us to the client, its ip-address, and
                     its ip-port.

       ${multiplexer_instance}::AddAccessFilter cmdprefix
              Command  to  add  an  access filter.  The registered cmdprefix is called when a new
              client socket tries to connect to the multixer instance. If there is more than  one
              access  filter  command registered at the instance they will be called in the order
              of registristation. If any of the called commands returns  -1  the  access  to  the
              multiplexer  instance  is  denied and the client channel is closed immediately. Any
              other result grants the client access to the  multiplexer  instance.   The  command
              prefix is called as

              cmdprefix chan clientaddress clientport
                     The  arguments contain information about the client which tries to connected
                     to the instance: The channel connecting us to the  client,  its  ip-address,
                     and its ip-port.

       ${multiplexer_instance}::AddExitFilter cmdprefix
              Adds  filter  to  be  run  when  client  socket  generates  an  EOF condition.  The
              registered cmdprefix is called when a client socket of the multixer signals EOF. If
              there  is more than one exit filter command registered at the instance they will be
              called in the order of  registristation.  Errors  thrown  by  an  exit  filter  are
              ignored, but logged. Any result returned by an exit filter is ignored.  The command
              prefix is called as

              cmdprefix chan clientaddress clientport
                     The arguments contain information about the client which signaled  the  EOF:
                     The channel connecting us to the client, its ip-address, and its ip-port.

BUGS, IDEAS, FEEDBACK

       This  document,  and  the  package  it  describes, will undoubtedly contain bugs and other
       problems.  Please  report  such  in  the  category  multiplexer  of  the  Tcllib  Trackers
       [http://core.tcl.tk/tcllib/reportlist].  Please also report any ideas for enhancements you
       may have for either package and/or documentation.

KEYWORDS

       chat, multiplexer

CATEGORY

       Programming tools