xmlrpclib and binary data as normal parameter strings

[Rune Froysa]

"Richard Brodie" <R.Brodie at rl.ac.uk> writes:

> "Rune Froysa" <rune.froysa at usit.uio.no> wrote in message news:svlacnvhrov.fsf at dresden.uio.no...
>
>> From http://www.xmlrpc.com/spec ::
>>   Any characters are allowed in a string except < and &, which are
>>   encoded as < and &. A string can be used to encode binary
>>   data.
>
> the XMLRPC specification is worded pretty loosely. Obviously characters
> forbidden in XML will be problematic.

IMHO that is not obvious.  The API-user wants to call a function on a
remote server with an arbitrary argument.  What the transport-layer
does to achieve this should be completly transparent to the user.

We already have code that takes care of "&<>".  Ideally we should do
that for other data as well.  Unfortunately the XML-spec doesn't allow
us to use character references "&%#x1b;".

With the patch below, setting BINARY_AS_STRING=True will cause all
strings to be transparently base64-encoded during transport.
Unfortunately it will do this for all incoming binary data, thus
breaking aplications that explicitly uses the Binary class for this
purpose.

IMHO the xmlrpc spec should be updated to allow something like this.

--- /local/lib/python2.3/xmlrpclib.py      2005-01-10 10:30:43.000000000 +0100
+++ xmlrpclib.py        2005-04-20 09:56:11.000000000 +0200
@@ -177,6 +177,8 @@
 
 __version__ = "1.0.1"
 
+BINARY_AS_STRING = False
+
 # xmlrpc integer limits
 MAXINT =  2L**31-1
 MININT = -2L**31
@@ -652,6 +654,11 @@
     dispatch[FloatType] = dump_double
 
     def dump_string(self, value, write, escape=escape):
+        if BINARY_AS_STRING:
+            self.write = write
+            Binary(value).encode(self)
+            del self.write
+            return
         write("<value><string>")
         write(escape(value))
         write("</string></value>\n")
@@ -843,7 +850,10 @@
     def end_base64(self, data):
         value = Binary()
         value.decode(data)
-        self.append(value)
+        if BINARY_AS_STRING:
+            self.append(value.data)
+        else:
+            self.append(value)
         self._value = 0
     dispatch["base64"] = end_base64
 
-- 
Rune Frøysa