[Python-bugs-list] [ python-Bugs-467384 ] provide a documented serialization func

[noreply@sourceforge.net]

Bugs item #467384, was opened at 2001-10-02 19:25
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=105470&aid=467384&group_id=5470

Category: None
Group: Feature Request
Status: Open
Resolution: None
Priority: 5
Submitted By: paul rubin (phr)
Assigned to: Nobody/Anonymous (nobody)
Summary: provide a documented serialization func

Initial Comment:
It would be nice if there was a documented library
function for serializing Python basic objects
(numbers, strings, dictionaries, and lists).
By documented I mean the protocol is specified in
the documentation, precisely enough to write
interoperating implementations in other languages.

Code-wise, the marshal.dumps and loads functions do
what I want, but their data format is (according to the
documentation) intentionally not specified, because
the format might change in future Python versions.
Maybe that doc was written long enough ago that it's
ok to freeze the marshal format now, and document it?
I just mean for the basic types listed above.  Stuff
like code objects don't have to be specified.  In
fact it would be nice if there was a flag to the
loads and dumps functions to refuse to marshal/
unmarshal those objects.

Pickle/cpickle aren't really appropriate for what I'm
asking, since they're complicated (they try to handle
class instances, circular structure, etc.) and anyway
they're not documented either.

The XDR library is sort of ok, but it's written in
Python (i.e. slow) and it doesn't automatically
handle compound objects.

Thanks



----------------------------------------------------------------------

>Comment By: Martin v. Löwis (loewis)
Date: 2001-10-12 02:39

Message:
Logged In: YES 
user_id=21627

Well, then I guess you need to specify your requirements
more clearly. XML-RPC was precisely developed to be
something simple for primitive types and structures that is
sufficiently  well-specified to allow interoperation between
various languages.

I don't see why extending the data 'by an order of
magnitude' would be a problem per se, nor do I see why
'requiring a complicated parser' is a problem if the
implementation already does all the unpacking for you under
the hoods.

Furthermore, I believe it is simply not true that XML-RPC
expands the representation by an order of magnitude. For
example, the Python Integer object 1 takes 12 bytes in its
internal representation (plus the overhead that malloc
requires); the XML-RPC representation '<int>1</int>' also
uses 12 bytes.
In short, you need to say as precise as possible what it is
that you want, or you won't get it. Also, it may be that you
have conflicting requirements (e.g. 'compact, binary', and
'simple, easily processible in different languages'); then
you won't get it either. For a marshalling format that is
accessible from different languages, you better specify it
first, and implement it then.

----------------------------------------------------------------------

Comment By: paul rubin (phr)
Date: 2001-10-11 22:12

Message:
Logged In: YES 
user_id=72053

I haven't looked at xmlrpclib, but I'm looking for
a simple, compact, binary representation, not something
that needs a complicated parser and expands the data by
an order of magnitude.

----------------------------------------------------------------------

Comment By: Martin v. Löwis (loewis)
Date: 2001-10-05 17:10

Message:
Logged In: YES 
user_id=21627

So what's wrong with xmlrpclib?


----------------------------------------------------------------------

You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=105470&aid=467384&group_id=5470