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

_________________________________________________________________

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     SF     Trackers
       [http://sourceforge.net/tracker/?group_id=12883].   Please also report any ideas for enhancements you may
       have for either package and/or documentation.

KEYWORDS

       chat, multiplexer

CATEGORY

       Programming tools

multiplexer                                            0.2                                     multiplexer(3tcl)