[Twisted-Python] Start-up code and passing its results
dkuhlman at cutter.rexx.com
Fri Jun 13 20:05:36 EDT 2003
Here is a seemingly simple question. But after searching the docs,
I still haven't figure it out.
How do I write some start-up code for a Web app, then pass values
from the start-up code to objects that respond to requests? In
particular, how do I create a DB ConnectionPool, then pass that to
the implementation of a Web page?
If the above question made sense, ignore the following. It's more
struggling with the same problem.
I'm learning Twisted. I've made quite a bit of progress, although
I'm slower than most. I've been able to build a small sample Web
application. I like what I find in Twisted so far.
After some digging, I've been able to use
enterprise.adbapi.ConnectionPool in one of my Web pages. But,
when I look in my log file, I see the messages "Connecting to
database: pyPgSQL.PgSQL" and "adbapi connecting: pyPgSQL.PgSQL"
for *every* time I visit that Web page. That makes me think that
I'm creating a new connection every time I deliver that Web page,
which, of course, a connection pool should eliminate. Am I right?
So, what am I doing wrong? I'm guessing that I should not be
running the following statement every time I deliver this Web page:
dbpool = adbapi.ConnectionPool("pyPgSQL.PgSQL",
So, my question is: Where do I put the above statement? And, how
do I share the same dbpool across delivery of that Web page and
across all sessions in my Web application?
By the way, I created my Twisted application with the following:
mktap web --path Test1 --processor=.rtl=twisted.web.script.ResourceTemplate
And, I start up my server with the fillowing:
twistd -f web.tap
Am I supposed to run mktap with the "--type=source" option, and
then create the connection pool in the resulting .tas file? If so:
1. How do I add code to the .tas file? How do I get it called
2. How do I pass the dbpool (or any variable) to the Web page?
Another way of asking this question is: How do I execute code at
server start-up? And, how do I make the results of that start-up
code available to the various parts of my application, in
particular to a Python module that implements the response to a
Or, am I trying to do things the non-Twisted way? If so, how do I
learn the Twisted way?
dkuhlman at rexx.com
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