1multiplexer(n)      One-to-many communication with sockets.     multiplexer(n)
2
3
4
5______________________________________________________________________________
6

NAME

8       multiplexer - One-to-many communication with sockets.
9

SYNOPSIS

11       package require Tcl  8.2
12
13       package require logger
14
15       package require multiplexer  ?0.2?
16
17       ::multiplexer::create
18
19       ${multiplexer_instance}::Init port
20
21       ${multiplexer_instance}::Config key value
22
23       ${multiplexer_instance}::AddFilter cmdprefix
24
25       cmdprefix data chan clientaddress clientport
26
27       ${multiplexer_instance}::AddAccessFilter cmdprefix
28
29       cmdprefix chan clientaddress clientport
30
31       ${multiplexer_instance}::AddExitFilter cmdprefix
32
33       cmdprefix chan clientaddress clientport
34
35_________________________________________________________________
36

DESCRIPTION

38       The  multiplexer package provides a generic system for one-to-many com‐
39       munication utilizing sockets.  For example,  think  of  a  chat  system
40       where one user sends a message which is then broadcast to all the other
41       connected users.
42
43       It is possible to have different multiplexers running concurrently.
44
45       ::multiplexer::create
46              The create command creates a new  multiplexer  'instance'.   For
47              example:
48              set mp [::multiplexer::create]
49              This instance can then be manipulated like so:
50              ${mp}::Init 35100
51
52       ${multiplexer_instance}::Init port
53              This starts the multiplexer listening on the specified port.
54
55       ${multiplexer_instance}::Config key value
56              Use Config to configure the multiplexer instance.  Configuration
57              options currently include:
58
59              sendtoorigin
60                     A boolean flag. If true, the sender will receive  a  copy
61                     of the sent message.  Defaults to false.
62
63              debuglevel
64                     Sets the debug level to use for the multiplexer instance,
65                     according  to  those  specified  by  the  logger  package
66                     (debug, info, notice, warn, error, critical).
67
68       ${multiplexer_instance}::AddFilter cmdprefix
69              Command  to add a filter for data that passes through the multi‐
70              plexer instance.  The registered cmdprefix is called  when  data
71              arrives  at  a  multiplexer  instance. If there is more than one
72              filter command registered at the instance they will be called in
73              the  order  of  registristation,  and  each  filter will get the
74              result of the preceding filter as its argument. The first filter
75              gets  the  incoming data as its argument. The result returned by
76              the last filter is the data  which  will  be  broadcast  to  all
77              clients  of  the  multiplexer  instance.   The command prefix is
78              called as
79
80              cmdprefix data chan clientaddress clientport
81                     Takes the incoming data, modifies it, and returns that as
82                     its  result. The last three arguments contain information
83                     about the client which sent the data to filter: The chan‐
84                     nel  connecting us to the client, its ip-address, and its
85                     ip-port.
86
87       ${multiplexer_instance}::AddAccessFilter cmdprefix
88              Command to add an access filter.  The  registered  cmdprefix  is
89              called when a new client socket tries to connect to the multixer
90              instance. If there is more than one access filter command regis‐
91              tered  at  the instance they will be called in the order of reg‐
92              istristation. If any of  the  called  commands  returns  -1  the
93              access  to  the  multiplexer  instance  is denied and the client
94              channel is closed  immediately.  Any  other  result  grants  the
95              client  access  to the multiplexer instance.  The command prefix
96              is called as
97
98              cmdprefix chan clientaddress clientport
99                     The arguments contain information about the client  which
100                     tries  to connected to the instance: The channel connect‐
101                     ing us to the client, its ip-address, and its ip-port.
102
103       ${multiplexer_instance}::AddExitFilter cmdprefix
104              Adds filter to be run when client socket generates an EOF condi‐
105              tion.   The  registered cmdprefix is called when a client socket
106              of the multixer signals EOF. If there is more than one exit fil‐
107              ter  command  registered  at the instance they will be called in
108              the order of registristation. Errors thrown by  an  exit  filter
109              are  ignored,  but logged. Any result returned by an exit filter
110              is ignored.  The command prefix is called as
111
112              cmdprefix chan clientaddress clientport
113                     The arguments contain information about the client  which
114                     signaled  the  EOF:  The  channel  connecting  us  to the
115                     client, its ip-address, and its ip-port.
116

KEYWORDS

118       chat, multiplexer
119
120
121
122multiplexer                           0.2                       multiplexer(n)