[Tutor] Trying to d0 HTTP GET

[Ertl, John]

This data set is 65160 bytes.  I am having a bit more success with urllib2
but still not there yet...byte swapping and such.  But now I think the
server is having problems.

Thanks for your help.

-----Original Message-----
From: Kent Johnson [mailto:kent37 at tds.net]
Sent: Monday, April 18, 2005 13:10
Cc: tutor at python.org
Subject: Re: [Tutor] Trying to d0 HTTP GET

Ertl, John wrote:
> All,
>
> I am trying to get some binary data from a web service.  None of the tech
> guys are around so I am hoping you might be able to shed some light on
what
> might be happening.

I would think that
f = urllib.urlopen(...)
data = f.read()

would work. You could try urllib2.urlopen() and see if it is any better.

How big is the data you are expecting?

Kent

>
> Here is part of the email that explained what I needed to do.
>
> ----- clip ---
>
> If you can do an http "get" from Python, you'll be set.
> 
>
http://dsd1u:7003/GRID:U:WW3_GLOBAL:2005041512:global_360x181:max_wav_ht:sur
> face:00000000:00000000:fcst_ops:0480
>
> It returns an http header like the following (if the grid exists),
> followed by the grid data in big-endian, IEEE format.
>
>          "HTTP/1.1 200 OK\r\n"
>          "Server: ISIS/4.0\r\n"
>          "Content-type: application/x-grid\r\n"
>          "Content-length: 261234\r\n\r\n"
>
> ----- end-----
>
> The grid data is in Binary.  How would I get to this?  I would imagine
that
> since f (the object) exists the call to the web service worked. Now I need
> to read the grid...eventually I need to put it into a Numeric array but
not
> sure how to get just the grid from "f".
>
> As a simple starting point I tried. 
>
>
>>>>import urllib
>>>>f =
>
>
urllib.urlopen("http://dsd1u:7003/GRID:U:WW3_GLOBAL:2005041800:global_360x18
> 1:max_wav_ht:surface:00000000:00000000:fcst_ops:0240")
>
>>>>f.info()
>
> <httplib.HTTPMessage instance at 0xb9255f6c>
>
>>>>f.readlines()
>
>
> I tried read(), readLines() and some other stuff using scipy and Numeric.
>
> The prompt has moved to the next line but nothing else has happened for 30
> min or so (I have tried several times).  When I try to close IDLE it says
> the program is still running.  How should I be getting this data is it
> trying to read the binary and that is why it is stalled? 
>
> Thanks,
>
> John Ertl
>
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