Tech Explorer

Many libraries around the world use EZproxy to provide access to electronic resources for our users. Most notably users who are off campus wouldn’t be able to gain access to the valuable resources that libraries subscribe to. While there are a variety of ways to achieve this goal, EZproxy is anecdotally the most popular.

EZproxy is the brain child of Chris Zagar who started work in EZproxy in 1999. In March last year Chris was the recipient of the 2006 LITA/Brett Butler Entrepreneurship Award. Those that would like to know more about EZproxy should check out the Useful Utilities website. Additionally you can check out my presentation, and report, hosted at the QULOC website that I presented in 2004.

A recent post by Peta Hopkins on her blog reminded me that getting RSS to work with EZproxy can be a bit difficult. The reason is that when an RSS aggregator requests an RSS feed it expects to receive an XML formatted response. The XML is the data of the feed feed. More information about RSS in general is provided by this Wikipedia article.

Trying to access an RSS feed via EZproxy typically will not work. The reason is due to authentication. The RSS aggregator, requests the RSS feed and EZproxy returns a web page asking for authentication information. Obviously this is not what is expected by the RSS aggregator.

The answer to the problem lies in a relatively new configuration stanza called AnonymousURL. It first became available in version 4.0a GA (2006-08-02) of EZproxy. Essentially the stanza instructs EZproxy not to prompt for authentication when a URL matches a specific pattern. This is perfect for RSS feeds because you can instruct EZproxy not to prompt for authentication for the URLs of RSS feeds.

A benefit of this approach is also that the links to the articles and full text in the RSS feed are rewritten so that they go through EZproxy. The user gets the best of both worlds. They can use whatever RSS aggregator that they like to read the RSS feeds provided by an electronic resource, and they get URLs that are rewritten that will allow them to access the full text of an article once they properly authenticate to the EZproxy server.

As an example take this EZproxy configuration for EBSCOhost used here at MPOW.

AnonymousURL -RE +http://rss.epnet.com/alertsyndicationservice/syndication.asmx/getfeed?guid=[0-9]+
Title EBSCOhost
URL http://search.ebscohost.com/login.aspx
DJ ebscohost.com
Host openurl.ebscohost.com
Host search.epnet.com
DJ epnet.com
HJ rss.epnet.com
Find proxy.cfm?url=http://
Replace proxy.cfm?url=http://^A
Find /login?url=http://
Replace /login?url=http://^A
AnonymousURL -*

This is a slightly modified version of the recommended configuration provided by Useful Utilities. Using this configuration it is possible to use an RSS aggregator to read an RSS feed provided by EBSCOhost when you change the URL slightly. For example using Peta’s alert as an example the URL for the RSS feed provided by EBSCOhost is this:

http://rss.ebscohost.com/AlertSyndicationService/Syndication.asmx/GetFeed?guid=1056713

To use it with EZproxy and the configuration above you’d change it to this:

http://rss.ebscohost.com.ezproxy.your-uni.edu.au/AlertSyndicationService/Syndication.asmx/GetFeed?guid=1056713

Where:

ezproxy.your-uni.edu.au

is the domain name of your EZproxy server.

If the EZproxy server is version 4.0g or above the URL used to access the RSS feed is even easier. All you need to do is prepend the usual prefix to the beginning of the URL. For example using the same RSS feed as above you could use this URL:

http://ezproxy.you-uni.edu.au/login?url=http://rss.ebscohost.com/AlertSyndicationService/Syndication.asmx/GetFeed?guid=1056713

A similar technique can be used for any electronic resource that provides RSS feeds, providing the majority of the URL for RSS feeds remains static. In this case only the guid of an EBSCOhost RSS feed URL changes which means the regular expression as specified in the AnonymousURL stanza will match any URL that starts the same and ends in a series of digits.

I encourage all systems administrators looking after EZproxy servers to investigate using this option to provide access to RSS feeds for their users because RSS is becoming very popular as a way of keeping up to date with information provided by electronic resource publishers.