multiplexer(3tcl) One-to-many communication with sockets. multiplexer(3tcl)
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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 com-
munication 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 (de-
bug, info, notice, warn, error, critical).
${multiplexer_instance}::AddFilter cmdprefix
Command to add a filter for data that passes through the multi-
plexer 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 re-
sult 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 chan-
nel 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 regis-
tered at the instance they will be called in the order of reg-
istristation. If any of the called commands returns -1 the ac-
cess to the multiplexer instance is denied and the client chan-
nel 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 connect-
ing 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 condi-
tion. The registered cmdprefix is called when a client socket
of the multixer signals EOF. If there is more than one exit fil-
ter 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 multi-
plexer 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.
When proposing code changes, please provide unified diffs, i.e the out-
put of diff -u.
Note further that attachments are strongly preferred over inlined
patches. Attachments can be made by going to the Edit form of the
ticket immediately after its creation, and then using the left-most
button in the secondary navigation bar.
KEYWORDS
chat, multiplexer
CATEGORY
Programming tools
tcllib 0.2 multiplexer(3tcl)