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Date: Thu, 18 Mar 2010 17:22:34 +0000 (GMT)
To: Ben DeMott <ben.demott@gmail.com>
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Subject: Re: [PHP-DEV] PHP Variable Storage / DBUS
From: derick@php.net (Derick Rethans)

On Thu, 18 Mar 2010, Ben DeMott wrote:

> So is the data structure thats being serialized remaining in some form 
> thats reflective of its binary encoding on the system. Or is there 
> some byte-encoding that goes on to generalize the binary structure?

PHP only knows about binary text, and then numbers and floats. Our 
current serialize format is just text based.

> I guess ... Does it find the values in memory of the distinct values,
> and then create a serialized set of indexes in a c-compatible
> data-type?
> or... is this just another form of string serialization, where
> variables are represented by strings encoded in ASCII?

The current serializer does do the latter. pecl/dbus does... DBUS 
serialization of course.

> If this is a binary serialization two additional questions:
> 1.) Does this mean that you can to some accuracy determine the size of
> an in-memory variable by counting the sizeof() on the components that
> make up the data-structure in C?

nope, that won't work as there are strings that are at least two blocks, 
and arrays and objects are tons.

> 2.) Can the PHP sessions serialization be made to use this type of
> serialization - so the serialized values could be shared between
> multiple applications.. (let me give you an example)

Thereis an igbinary extension/serializer.

>      Would I be better off just re-implementing the PHP C code for its
> session serializer/deserializer in Python than attempting to keep it
> binary?

What you want... both work.

> For PHP Sessions, lets say you use memcached to store a serialized
> representation of the session.
> Lets also say that you would like to read that session data
> occasionally by python to offload work that your webserver would
> normally have to perform.
> 
> If you were to write a binary serialized form to memory - the C
> implementation of the serialization could by very easily ported to
> Python as an extension and both could be maintained with ease
> (as both PHP and Python are written in C, a Java variant wouldn't be
> too hard either using JNI)

The problem is that PHP and Python have different dataytpes, and dbus 
has yet again others. That is always going to be a problem.

> I guess this brings up the question of - How hard would it be to
> expose the binary object that dbus sends over-the-wire so it could be
> written to file instead?

You need a tool such as dbus-monitor, but you need to write the 
deserialization from DBUS into your "fileformat" yet again.

> Overall it would be nice if PHP had a functionality similar to Pythons
> Pickle -> to expose to the user so they could store binary
> representations of objects as they saw fit.
>
> It seems to me this would be vastly more efficient than an
> ascii-encoding and serialization as well.

That's no different from what serialization does really. There is 
http://opensource.dynamoid.com/ for binary serializations.

> If my logic is poorly formed because of a lack of understanding please
> feel free to educate me!

You write too much text :P

regards,
Derick

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