Liberal versus strict XML parsing (Anders Jacobsen's blog)

August 21, 2002

Liberal versus strict XML parsing

Joe, the creator of Aggie disagrees (at least to a vertain degree) with Mark's rant "Ultra-liberal RSS parsers":

But if we all build parsers that accept non well-formed XML then where is the motivation to fix those feeds? Where is the motivation for the developers of tools that produce non well-formed RSS to fix their products? If it is no longer XML than I can't use off-the-shelf XML parsers nor can I stuff the feed through an XSLT transform. If it ceases being valid XML then it is not as amenable to the wonderful re-purposing that the internet allows.

Ziv suggests the "middle road" for the next version of Aggie:

I propose a "shame them into submission" scheme. Each feed that is not well-formed will be marked by Aggie (and hopefully other aggregators) by a shameful icon that claims the feed is not well-formed. In my experience, weblog authors that receive requests to modify their feeds because of well-formedness issues usually jump on the opportunity to improve.

Don Box shares Ziv's view.

An old fundamental of Internet Netiquette that I still am a believer in is

Be conservative in what you send and liberal in what you receive.

It was originally (I think) meant for content of for example emails, but has also been adopted for technical services like smtp (mail) servers. Fundamentally, I think this principle should apply also in the world of RSS and news aggregators: behave properly and according to all protocols, but expect and accept the unexpected. Providing feedback to the creator of the malformed feeds like Ziv and Don Box is a "bonus" in my view...

I look forward to Aggie RC5 so I can start reading boingboing (rss), scripting news (rss) and The Register (rss)!