Java supports and encourages socket communication using UTF-8. To this end two methods are provided: readUTF() [L1 ] and writeUTF() [L2 ]. Socket communication between a Java process that uses these methods and Tcl is easy. First, you will have to put your socket in binary mode, through a command such as the following:
fconfigure $socket -translation binary
Specifying the translation is a shortcut for not having any conversion, for not having CRLF at the end of your lines, etc.
The rest of the code on this page issues from a discussion between DKF and EF on the chatroom. Both functions should help you reading and writing data to a socket coupled to a Java process using the methods above for its communication with the external world. Error handling is minimal.
proc writeJavaUtf {stream string} {
set data [encoding convertto utf-8 $string]
if {[string length $data] > 0xffff} {
error "string to long after encoding"
}
set len [binary format S [string length $data]]
puts -nonewline $stream $len$data
flush $stream
}
proc readJavaUtf {stream} {
set len [read $stream 2]
binary scan $len S length
set data [read $stream [expr {$length & 0xffff}]]
return [encoding convertfrom utf-8 $data]
}