Once upon a time, I was very interested in computing complexity theory. I wish I could remember, now, the subtleties of the theory. But I remember enough to be interested in the purported proof that P != NP. Very interesting.

I just finished a conference call with a vendor who built and uses their own “cloud” to host applications for their customers.    There were several lessons they learned along the way.   Without comment, here are some of the lessons they mentioned:

• XEN works great for building internal clouds.   They tried VMWare, which worked, but was far too expensive
• Building an internal cloud was far more work than they thought.
• Sizing an internal cloud is tricky.  By the time you complete an internal cloud build – which will be longer than you think, the technology will have shifted significantly and become much cheaper
• They used a SAN for storage in the cloud
• The cloud has changed their business – they used to run hosted services (the ASP model), but were always suffering because every customer wanted customization.   They now deal with that via virtualization – they just run, say, customized versions of Exchange in multiple VMs
• The recession helps cloud companies – because companies don’t want to spend on IT but are willing to spend “operational” costs.

Tab sweep of items I reviewed regarding how social policies support or enable the success of wikis:

General Wiki Statistics

Examples of Wikipedia policies / social roles

The study of wikis and why and how they work

Specific Papers I found enlightening

I’ve been wrestling for a while trying to find a good technique for large scale graph processing. Some wonderful folks here at work have come up with some cool solutions based on map-reduce.

Today, however, Google sent out a tease about their in-house solution — Pregel. It will be interesting to see what the details are when they discuss it.

Current tabs

• Blog entry from Matthew Hurst exploring Google^2
• Blog entry from William Cohen, discussing the above entry and SEAL
• Google^2
• SEAL

I’m swapping into working memory the history and relationships of URLs, URNs, and URIs….

• IETF URI Working Group
• Tim Bray on identifiers
• And again
• Untangle URIs, URLs, and URNs

Credit to Car Talk:

I can’t begin to count the number of times that I’ve seen it (and, sadly, participated sometimes — I like to believe I’m wiser now)….

Posit the question: Do two people who don’t know what they are talking
about know more or less than one person who doesn’t know what he’s
talking about?

One person will only go so far out on a limb in his construction of
deeply hypothetical structures, and will often end with a shrug or a
raising of hands to indicate the dismissability of his particular take
on a subject. With two people, the intricacies, the gives and takes,
the wherefores and why-nots, can become a veritable pas-de-deux of breathtaking speculation, interwoven in such a way that apologies or gestures of doubt are rendered unnecessary.

John Engales, the CTO of Rackspace, has written a presentation about the typical stages of scalability undergone by a website.

By it’s own description, “Scalr is a fully redundant, self-curing and self-scaling hosting environment utilizing Amazon’s EC2″. While I haven’t yet tried it, there certainly seems to be a market for management tools riding on top of EC2. Rightscale.com, a commercial alternative to Scalr, can attest to that.

I find the type of automation offered fairly compelling. We are approaching the day where deploying your application at internet scale will be push-button simple. Perhap’s Time’s person of the year this time ’round should be a cloud.

I wrote an implementation of Bloom Filters which you can download from here. This implementation offers some advantages

• Pluggable hash functions
• Pluggable “bit stores” (an array of bits)
  • An option to store the bloom filter in a file on disk. This allows for bloom filters bigger than your JVM heap by using Memory Mapped Files
  • An option to store the bloom filter in ram.

Instructions for using the bloom filter are in the javadocs.