forking a process and grabbing web site data from a C trigger?

On Sat, Aug 12, 2000 at 01:10:01PM -0400, Tom Lane wrote:
> Louis-David Mitterrand <cunctator@apartia.ch> writes:
> >> IMPORTANT: changing the backend's locale on-the-fly is an EXTREMELY
> >> DANGEROUS thing to do, and I strongly recommend that you find another
> >> way to solve your problem.
>
> > The "problem" I am trying to solve is to send e-mail notifications to
> > auction bidders in their own language with the proper number formatting,
> > etc. From what you are saying I'll probably have to move these
> > notifications to the mod_perl layer of the application.
>
> Well, you could fork a subprocess to issue the mail and change locale
> only once you're safely inside the subprocess.

Could you give a minimal example of how forking a subprocess in a PG
trigger is done? Or maybe give a pointer to an existing example?


On an unrelated subject I have to maintain and update a table containing
currency rates for the auction site (URL in .sig):

            Table "currency"
 Attribute |  Type  |      Modifier
-----------+--------+--------------------
 USD       | float4 | not null default 1
 FRF       | float4 |
 AUD       | float4 |
 CAD       | float4 |
 EUR       | float4 |
 GBP       | float4 |
 DEM       | float4 |
 JPY       | float4 |
 CHF       | float4 |

To update it I wrote a quick perl script that grabs data from Yahoo's
currency web page (attached). This script has to be installed and run as
a cron job, but I'd like to integrate that functionality in the DB
backend as a trigger that performs the data refresh every n'th SELECT on
the table:
    - either convert that perl script to C (maybe using libwww and a
      regex C library);
    - or simpy launch that perl script from the trigger;
The former solution is not easy, and is probably a good programming
exercise, the latter is quick but how would one go about launching a
perl script from C without waiting for its completion?

Thanks in advance,

--
Louis-David Mitterrand - ldm@apartia.org - http://www.apartia.org

       Parkinson's Law:  Work expands to fill the time alloted it.