on encode_char(this_char)
    set the ASCII_num to (the ASCII number this_char)
    set the hex_list to {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"}
    set x to item ((ASCII_num div 16) + 1) of the hex_list
    set y to item ((ASCII_num mod 16) + 1) of the hex_list
    return ("%" & x & y) as string
end encode_char

on encode_text(this_text, encode_URL_A, encode_URL_B)
    set the standard_characters to "abcdefghijklmnopqrstuvwxyz0123456789"
    set the URL_A_chars to "$+!'/?;&@=#%><{}[]\"~`^\\|*"
    set the URL_B_chars to ".-_:"
    set the acceptable_characters to the standard_characters
    if encode_URL_A is false then set the acceptable_characters to the acceptable_characters & the URL_A_chars
    if encode_URL_B is false then set the acceptable_characters to the acceptable_characters & the URL_B_chars
    set the encoded_text to ""
    repeat with this_char in this_text
        if this_char is in the acceptable_characters then
            set the encoded_text to (the encoded_text & this_char)
        else
            set the encoded_text to (the encoded_text & encode_char(this_char)) as string
        end if
    end repeat
    return the encoded_text
end encode_text

using terms from application "Messages"
    on message received theMessage for theChat
        set theURL to "http://MYSERVER.COM/mirror-quickstart-php/sendText.php?auth=superSecretCodew&message=" & encode_text(theMessage, false, false)
        do shell script "curl " & quoted form of theURL
    end message received
end using terms from