Re: [DotGNU]Help required in writing Python VM for DGEE

[Chris Smith]

On Tuesday 22 Apr 2003 09:30, Norbert Bollow wrote:
> Chris Smith <address@hidden> wrote:
> > This involves taking the C nullVM example in the DGEE src tree, copying
> > it to say pythonVM and linking in the python core with appropriate API
> > calls.  It's all pretty well documented.  This pythonVM would receive
> > python code to execute, which it should do, and then pass back the
> > result.
>
> Hmmm... for Abdabi I need a somewhat more sophisticated set-up:  The
> pythonVM loads the Python bytecode for the Abdabi server, and then the
> server will service incoming webservice requests.  Each request will
> be handled by a separate thread.

Ooh. This will not work - you're thinking about your own scalability 
(threading) and server set up. This is not required with the DGEE as it does 
this all for you by providing multiple 'servers', many of each bytecode type 
- this effectively gives you the threading you want but also allows you to 
cluster multiple machines together as a single 'dgee' to give you an 
additional kick of power.  You can't do that with threading :o)

When you say "and then the server will service incoming webservice request" 
what do you mean my 'server' ? The DGEE or your python blob?

The webservices that run are effectively short-lived 'access' services.  It is 
possible to have a daemon running in the background that these webservices 
can call, but then you have the issue of security and sandboxing and all that 
(SEE guise etc).

Since each of the 'python' servers are not persistent in the DGEE they will 
need some sort of state retention - this is planned for DotGNU 0.1, but is a 
little tricky and involves internal calls for pnet and some SWIG setup for 
python - so it might just miss 0.1, we'll have to see.

The VM's however will 'cache' bytecode they are asked to execute for 
performance reasons.  This is still a TODO.

For arguments sake, think of the DGEE as a glorified webserver that allows you 
to run CGI's

To be honest, I'm having difficulty with one aspect of the whole .net scenario 
which is if you're a webservice supplier and need some sort of persistently 
running back end 'server' process, you've got to get the system administrator 
to install this for you.  Imagine you wrote your own MySQL on which your 
webservices relied, and you need it running all of the time.... I just can't 
think of a way to do this at the moment - and it's annoying me :o)

I don't think this should cause you too much trouble Norbert, just a slight 
adjustment in the angle at which you tackle the problem.

[The exception being the whole 'search the web' thing of data capture for the 
Abdabi server..... this would NOT run as a webservice but as a background 
process or something like that that crawls away in the background ???]

This is dead interesting ! 
Something else to talk about... hehe.
Lets talk !

Chris
-- 
Chris Smith
  Technical Architect - netFluid Technology Ltd.
  "Internet Technologies, Distributed Systems and Tuxedo Consultancy"
  E: address@hidden  W: http://www.nfluid.co.uk