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From CHRIS A MATTMANN <Chris.A.Mattm...@jpl.nasa.gov>
Subject Re: RSS Parser Bug!?
Date Thu, 08 Sep 2005 14:11:30 GMT
Hi Jack,

  I'm not necessarily sure that this is a "bug" per se: it's just the fact that several different
content types are potentially possible when any ol' webserver returns an RSS file. To be honest,
I performed a pretty detailed crawl (100s of thousands of pages) when I originally wrote the
plugin way back in March/April of this year, and the two content types that you see in the
code right now that it checks for are what I found to be the most pervasive content type returned
from webservers for RSS. However, in no way did I mean for that list to be exhaustive: for
instance, web servers may also return "application/rss", or "text/rss", or even "text/plain"
I have seen for RSS. It all depends on how the webmaster has configured the web server. So
it's kind of difficult to accurately and reliably discriminate against the content type within
a parser plugin itself, because it is inherently out of the parsers hands what gets returned
for a particular type of file, and even though th!
 ere are some "best practices" for what should be returned for different file types, there
is by no means any "standards", that must be followed.

So, I would propose the following. I believe the checking for the content type and then throwing
an exception block of code exists in other plugins in Nutch as well. I propose we nix that,
and remove the content type checking and exception message from the plugins themselves, and
move it up to a higher level, i.e., the actually plugin factory or something. Let it get taken
care of there, and let it be configurable, out of the code of each plugin for instance. Because
that way, I believe you can customize whatever plugin to do whatever your need is, * without
* having to recompile the code just to add another accepted content type to a plugin so it
doesn't throw an error message.

What say you guys? :-)

Cheers,
  Chris


----- Original Message -----
From: Jack Tang <himars@gmail.com>
Date: Wednesday, September 7, 2005 10:58 pm
Subject: RSS Parser Bug!?

> Hi Guys
> 
> Did someone install parse-rss and try to fetch rss feeds?
> It failed on my side. I enabled the plugin and it fetched, not rss
> parser didnot work.
> My feed is http://www.craigslist.org/evs/index.rss
> 
> Here is the error:
> 
> org.apache.nutch.fetcher.Fetcher$FetcherThread [11] - fetch okay, but
> can't parse http://beijing.craigslist.org/jjj/index.rss, reason:
> failed(2,203): Content-Type not text/html: application/xml;
> charset=ISO-8859-1
> 
> The content-type is application/xml. Mattmann's comment is this:
>        // check that contentType is one we can handle
>        String contentType = content.getContentType();
>        if (contentType != null
>                && (!contentType.startsWith("text/xml") &&
> !contentType.startsWith("application/rss+xml")))
>            return new ParseStatus(ParseStatus.FAILED_INVALID_FORMAT,
>                    "Content-Type not text/xml or 
> application/rss+xml: "
>                            + contentType).getEmptyParse();
> 
> So, it does not "application/xml" content type yet?
> 
> 
> Thanks
> /Jack
> -- 
> Keep Discovering ... ...
> http://www.jroller.com/page/jmars
> 


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