multiplexer (3)
NAME
multiplexer - One-to-many communication with sockets.SYNOPSIS
package require Tcl 8.2package 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:
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set mp [::multiplexer::create]
-
-
This instance can then be manipulated like so:
-
${mp}::Init 35100
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- ${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).
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- ${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.
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- ${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.
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- ${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.
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