ns_sockcallback - Register a socket callback script
Command for registering a socket callback script.
Registers command as socket callback, which is fired based on the information in the when parameter. This parameter can consist of one or more characters of r, w, e, or x, specifying, when the callback should fire. The meaning of these characters is as follows:
r - the socket is readable
w - the socket is writable
e - the socket has an exceptional condition
x - the server is shutting down
The optional argument timeout can be specified in the form secs?:microsecs?, or secs.fraction, or as a number with a time unit.
When the callback is fired, the specified command is called with additional arguments sockId and condition. The value of the reported condition will be as follows:
r - the socket is readable
w - the socket is writable
e - the socket has an exceptional condition
x - the server is shutting down
t - timeout received
#
# Opening a listen socket
#
set sock [ns_socklisten * 9000]
#
# Register the proc "newconn", which is fired when the socket
# becomes readable. When this is the case (e.g. a connection
# arrives), "newconn" will be called as: "newconn $sock r"
#
ns_sockcallback $sock newconn r
# Keep $sock from closing after connection ends
detach $sock
#
# Definition of the proc "newconn"
#
proc newconn {sock when} {
set fds [ns_sockaccept $sock]
set rfd [lindex $fds 0]
set wfd [lindex $fds 1]
puts $wfd "Hello!"
close $rfd
close $wfd
}