Monthly Archives: April 2010

The Swimming Pool Model of Public and Private Clouds

This morning, I recorded a podcast with Keith Shaw from Network World. Our discussion was about the 5 mistakes people make when moving out into the cloud. The podcast should be available next week, but in the meantime, I thought I would share a nice analogy that Keith came up with illustrating the difference between public and private clouds.

Clouds are like swimming pools. Private clouds are like a pool in your backyard. Every pool has a fence for reasons of practicality and liability. Since this is your pool, you get to decide who is allowed to go for a dip. Sometimes there is only one person in the pool; sometimes there’s ten—but anybody going for a swim is your responsibility. Each day you add chlorine and keep up with the cleaning. But more likely, you hire someone to do this for you.

Public clouds are like public pools. Someone else—probably the city—builds the pool and maintains it. Anyone who can pay the admission is welcome, as long as they agree to follow a few simple rules. There are lifeguards to watch over you and your kids, and you trust the pool management has checked them out to make sure they are trustworthy and posses the proper credentials. Often the public pool is crowded, and there is this annoying fat kid that keeps doing cannonballs close to where you are swimming, but overall it provides good value. True, once you came home with a strange itch, but the local public pool is certainly cheaper and a lot less work than maintaining your own.

It’s just too bad they don’t serve daiquiris.

XML Acceleration Using Virtual Appliances

I have never met Gordon Moore. But his law? Well, Moore’s Law is my best friend. My entire career, it helped to make my work run faster. On more than one occasion, I think it may have saved my job. I like Moore’s Law a lot.

Moore’s Law has had a big impact on XML acceleration. XML processing—specifically schema validation, XSLT transform and XPath query—is one of those problems that lends itself well to acceleration using specialized silicon. Tarari (now a part of LSI) is the leader in developing specialized chip sets for accelerating basic XML functions. We’ve leveraged their technology for years here at Layer 7 for our hardware appliance line, and we will continue to do so in the future. But like all specialized chip designers, Tarari’s engineers are engaged in a protracted battle with the ever-increasing capacity of general-purpose processors. Dr. Moore’s Law pursues them with a relentless pace, driving Tarari toward the breakthroughs that leave general CPUs far behind each time these begin to nip at their heels.

Silicon, however, is not the only approach to accelerating XML. Tremendous gains in XML processing can also be realized using highly optimized, pure-software algorithms that run on generic CPUs. These, of course, effortlessly ride the wave of Moore’s law. We use such algorithms at Layer 7 to provide very real XML acceleration in our virtual appliances, which obviously have no access to dedicated acceleration boards.

This fact that virtual appliances can accelerate XML processing is often missed. I was reminded of this when reading Joe McKendrick’s latest blog entry  The Case for Considering XML Appliances. Joe’s entry builds off a recent piece published by Thomas Rischbeck from IPT concerning SOA intermediaries (I’m particularly fond of the last diagram in Thomas’ article). As with all of Joe’s work, his article today is very perceptive, but I disagree with one statement he makes:

And, as is the case with appliances these days, they also come in virtual form as well. The only catch is that virtual XML appliances cannot provide XML acceleration.

I see XML acceleration as a continuum like this:

Virtual appliances may not be as fast as hardware appliances for XML acceleration, but they do accelerate processing over conventional approaches. And one of value propositions of virtual appliances is that these provide a simple means to scale horizontally (in clouds, or in conventional virtualization farms) instead of vertically. Moore’s Law is its friend too.

Layer 7 Technologies is the only SOA Gateway vendor that offers a product line that features both hardware and virtual appliances. You can buy the hardware SecureSpan Gateway appliance that includes silicon for XML acceleration. Or you can buy the virtualized SecureSpan Gateway appliance that includes our highly tuned algorithms for XML acceleration. These products offer identical functionality—so choose the one that makes the most sense in your architecture.

And don’t ever let a form factor dictate your architecture.

All Things Considered About Cloud Computing Risks and Challenges

Last month during the RSA show, I met with Rob Westervelt from ITKnowledgeExchange in the Starbucks across from Moscone Center. Rob recorded our discussion about the challenges of security in the cloud and turned this into a podcast. I’m quite pleased with the results. You can pick up a little Miles Davis in the background, the odd note of an espresso being drawn. Alison thinks that I sound very NPR. Having been raised on CBC Radio, I take this as a great compliment.

Pour yourself a coffee and have a listen.