[Zope] httplib (was re:throwing exceptions when <img src=...> does not exist)

[Luciano Ramalho]

We have a site with thousands of product images that are supplied by a
third party. In our case, the supplier FTPs the images to the filesystem
of the machine where Zope runs. Whenever we render a page, we invoke a
very simple external method which checks whether the image exists in the
filesystem, and generates its <img> tag. If the image us unavailable, a
<img> tag refering to a default image is generated.

I understand your case is more complicated, because the images are in a
different machine. Any way, I can send you the External method if you
like. 

Regards,

Luciano

Lee Reilly CS1997 wrote:
> 
> thanks, john.
> 
> this looks like the best option. uploading the files to my zope server
> is not really an option. i've set up database simply recording, which
> files are held on the external server to help (as a short-term solution)
> but this would prove just as tedious in the long run and there's no way
> i'd include this is my final build.
> 
> so...
> 
> i checked out httplib module (HTTP protocol client)
> ref:
> http://www.gmu.edu/mlnavbar/webdev/doc-python/lib/module-httplib.html
> 
> but it doesn't seem to be supported by python methods. i've managed to
> create a total system so far without using any external python methods
> (the ones stored in an extension but this seems like the only option
> now.
> 
> can anyone tell me if there are any alternatives?
> 
> thanks if you can help,
> 
> lee
> 
> John wrote:
> 
> > - Write an external method that goes out and checks whether the image in
> > question actually exists on the server. You might need to do an HTTP HEAD
> > on the expected image URL, but this is roughly what the user's browser
> > will have to do, so it's pretty much the canonical test.
> 
> for more info on *exactly* what i'm trying to do here's a message posted
> this to comp.lang.python:
> 
> - sorry for the larger than normal post :-o
> 
>   ------------------------------------------------------------------------
> 
> Subject: retrieving file data from an external server - where to start?
> Date: Tue, 20 Feb 2001 16:20:03 +0000
> From: Lee Reilly CS1997 <lreilly@cs.strath.ac.uk>
> Organization: Department of Computer Science, University of Strathclyde
> Newsgroups: comp.lang.python
> 
> hi there,
> 
> i'm using python with zope and am trying to do the following with python
> method:
> 
> retrieveFileInfo(matric){
> 
>   username = getUsername(matric)
>   filename = username + ".gif"
>   server = "http://blahblahblah/yaddieyaddie/"
> 
>   # some code to determine whether or not the file exists
>   # where do i start
>   # e.g if (retrieve.(server+filename) != none):
>   #        do something
> }
> 
> e.g. given the matric value '9728430' i find that the corresponding user
> has username == 'lreilly'. if this person has their image stored on the
> external server then it will be called 'lreilly.gif'.
> 
> i don't need to actually retrieve the file from python - only determine
> whether or not it exists or not. i.e. whether the http request reports a
> 404 or maybe even if the image size == 0 bytes.
> 
> could someone possible be kind enough to give me an idea where to start?
> a url? a snippet of code?
> 
> thanks very much in advance,
> 
> lee