[Tutor] Testing for response from a Web site

[Henry Steigerwaldt]

To All:

How can I test the response of a server on a Web site to a
request that occurs when I attempt to access the Web site?
I am using the Windows XP operating system.

For example, if I select a link to a Web site, the server can
respond in (I think) only 3 different ways:

1)  It can simply ignore the request.
2)  It can honor the request and I can therefore download
     some data, or...
3)  It might send my PC some other response that I can 
     test for in a Python program, that tells the program that
     the site is not accessible or available.  

Here is the code I am using:
_________________________________________________
   metURL = "http://isl715.nws.noaa.gov/tdl/forecast/tdl_etamet.txt"
   f_object = open("c:\\python_pgms\\plot_guidance\\met_data.txt", 'w')

   try:
      print "\nBEGIN DOWNLOADING ETA (MET) MOS"
      metall = urllib.urlopen(metURL).read()
      f_object.write(metall)
      f_object.close()
   except:
      print "Could not obtain data from Web"
      f_object.close()
____________________________________________________
As it stands now, the program will just say the data is old, when I
really should say something like "could not connect with the site."

What additional test(s) can I perform to catch other responses from
a server, especially one in which the server will not honor my 
request?

Thanks for any help. 

Henry Steigerwaldt
Hermitage, TN
Email:  hsteiger@comcast.net