Sending binary pickled data through TCP

Nick Craig-Wood nick at craig-wood.com
Fri Oct 13 10:30:10 CEST 2006


Paul Rubin <http> wrote:
>  As for the network representation, DJB proposes this format:
>  http://cr.yp.to/proto/netstrings.txt

Netstrings are cool and you'll find some python implementations if you
search.

But it is basically "number:string,", ie "12:hello world!,"

Or you could use escaping which is what I usually do.  This has the
advantage that you don't need to know how long the data is in advance.

Eg, these are from a scheme which uses \t to seperate arguments and
\r or \n to seperate transactions.  These are then escaped in the
actual data using these functions

def escape(s):
    """This escapes the string passed in, changing CR, LF, TAB and \\ into
    \\r, \\n, \\t and \\\\"""
    s = s.replace("\\", "\\\\")
    s = s.replace("\r", "\\r")
    s = s.replace("\n", "\\n")
    s = s.replace("\t", "\\t")
    return s

def unescape(s, _unescape_mapping = string.maketrans('tnr','\t\n\r'), _unescape_re = re.compile(r'\\([(rnt\\)])')):
    """This unescapes the string passed in, changing \\r, \\n, \\t and \\any_char into
    CR, LF, TAB and any_char"""
    def _translate(m):
        return m.group(1).translate(_unescape_mapping)
    return _unescape_re.sub(_translate, s)

(These functions have been through the optimisation mill which is why
they may not look immediately like how you might first think of
writing them!)

-- 
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick



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