If you read this blog, you probably paid a smidgen of attention to the Web 2.0 Conference held last week in San Francisco. Sphere was one of the companies that presented and they launched a product called the “Sphere It Contextual Widget for blogs“, which is JavaScript widget you can add to your blog or content focused site that displays contextually similar blogs and blog posts for the reader. I’ve always wanted to try to do something similar (no pun intended) using Lucene, so I spent a couple hours this weekend banging around on it.

The first step was to get my WordPress content (which is stored in MySQL) into Lucene. A couple lines of code later I had a Lucene index full of all 857 (as of 11/14/2006) posts including the blog post ID, subject, body, date and permalink. Next, I checked out and compiled the Lucene similarity contrib, whose most important asset is the MoreLikeThis class (written in part by co-worker Bruce Ritchie). You provide an instance of MoreLikeThis a document to parse, an index to search and the fields in the index you want to compare against the given document and then execute a Lucene search just like you normally would:

Reader reader = ...;
IndexReader index = IndexReader.open(indexfile);
IndexSearcher searcher = new IndexSearcher(index);
MoreLikeThis mlt = new MoreLikeThis(index);
mlt.setFieldNames(new String[] {"subject", "body"});
Query query = mlt.like(reader);
Hits hits = is.search(query);

I’ll skip all the glue and say that I wired all this up into a servlet that spits out JSON:

Map entries = getRelatedEntries(postID, body);
JSONObject json = JSONObject.fromObject( entries );
response.setContentType("text/javascript");
response.getWriter().write("Related = {}; Related.posts = " + json.toString());

and then used client side JavaScript and some PHP to put it all together:

<h5>Related Content</h5>
<script type="text/javascript"
  src="http://cephas.net/blog/related.js?post=<?php the_ID(); ?>">
</script>
<script type="text/javascript">
for (post in Related.posts) {
document.write('<li><a href="' + Related.posts[post] + '">' + post + '</a></li>');
}
</script>

I’ve been cruising around the blog and so far, I think that MoreLikeThis works really well. For the most part, the posts that I would expect to be related, are related. There are a couple posts which seem to pop to the top of the ‘related content’ feed that I’ll have to fix and I would like to boost the terms in the subject of the original document, but other than that, I’m happy with it.

Back to sphere, and specifically to Brady’s post about it on the Radar blog:

Top-Left Corner: Recent, similar blog posts from other blogs.
Bottom-Left Corner: Recommended blogs that are selected by the site-owner. This is very handy for blog networks.
Top-Right Corner: Similar posts from that blog
Bottom-Right Corner: Ad, currently served by FM Pub.

Given a week, I’m guessing that you could use the Google API to do the top-left corner, hardcode the content in the bottom left, use MoreLikeThis in the top right and the bottom right you’d want to do yourself anyway. So if you were a publisher looking for more page views, why would you even consider the Sphere widget?