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[IDV #KOO-280301]: Reading data via URLs in IDV: setting Content-Length and Accept-Ranges headers

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  • Subject: [IDV #KOO-280301]: Reading data via URLs in IDV: setting Content-Length and Accept-Ranges headers
  • Date: Tue, 10 Jun 2008 09:20:46 -0600
Hi Dave,

> If the Content-Length and Accept-Ranges: bytes headers are in the default
> setup for Apache 2.2 on Macs under Leopard, I don't see them (in the
> httpd.conf file). Would they be somewhere else? (I read somewhere that
> Content-Length isn't specified by default because that could potentially
> interfere with dynamic Web page creation, something my I don't ask my Web
> servers to do.)

These headers are not the same as configuration directives that would be in 
httpd.conf. Rather, they are HTTP response headers that are returned by the 
server in response to a client's (e.g., browser or IDV) request. For instance, 
when a browser requests a web page, say http://some.server/coolpage.html, the 
response might look like:

HTTP/1.x 200 OK
Server: Apache
Accept-Ranges: bytes
Content-Length: 1500
Content-type: text/html

<html>
  ...
</html>

There are a number of tools for looking at the request and response headers for 
a particular request/page. If you are using FireFox, the "Tools -> Page Info" 
menu item will bring up a window with lots of information. The "Headers" tab 
will show both request and response headers for the page you are on. (I would 
imagine other browsers would have similar features but I'm not as familiar with 
them.)


> The IDV won't load files accessed via URL from my two Web servers, whereas
> the IDV loads the same files from the same locations just fine when
> accessing them as local files. (I say "files" generically, but I'm not
> sure the problem applies to all files or just those that it's trying to
> read parts of, such as numerical model output in GRIB(2) format.)

What kind of behavior are you seeing from the IDV? Is it just failing silently 
or are there error messages? If you can take a look at the headers for a 
particular request/response, we can hopefully decide if that is the problem or 
not.

It should be able to access netCDF, GRIB1, and GRIB2 files in this way.

Ethan


Ticket Details
===================
Ticket ID: KOO-280301
Department: Support THREDDS
Priority: Normal
Status: Open