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:
- ${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