I have been musing lately about the connection between software delivered as a service and hardware virtualization. For me they are two sides of the same coin (I guess we could have just as easily called it Hardware-as-a-Service and Software Virtualization). The simplest way to implement a SaaS’ified version of an existing application is via Virtualization – just run as many instances of the application (or application components) as needed, each in their own virtual machine.

The down side is that this may not be very cost effective. First, you need to be able easily deploy and manage new instances of the application within you virtual environment (and hence VMWare’s acquisitions of Akimbi and Dunes), have a appropriate pricing model for the various components technologies that make up the application, and the ability to easily monitor the virtual vs. real machine resources needed for the application.

It is not always easy to reconcile the software component models with virtualization. Many traditional software vendors charge per instance of their application deployed on a server. So if you want to deploy a DBMS for each instance of the application – the price can be quite prohibitive. It would probably depend heavily on the number of users per instance, but for many SaaS applications there are only a few users per instance. You could rewrite the application so that you could use a shared DBMS, having each application instance use a different DB in the DBMS – but rewriting an application is very costly.

Monitoring all those instances isn’t easy either. You somehow need to correlate all the virtual instances with the physical resources on the machine. One of the key reasons to virtualize is to be able to use machine resources (especially the CPU) more effectively – which means you want to load as many instances as possible before having to buy a new machine – very different then what is available from today’s monitoring tools.  A good overviewof these issues by Bernd Harzog can be found here.

So what’s my point? I think that we’ll see SaaS take-off when it really easy to take an existing app, and created a SaaS’ified version of it – and that will happen when it is as easy as taking a “virtual version” of the application and deploying it for “tenant” as needed. We are still missing some pieces of the puzzle for that to happen, but my guess is that we will see it happen in the next couple of years.

Stumble it!

This entry was posted on Thursday, November 15th, 2007 at 9:01 am and is filed under Innovation, enterprise 2.0, software. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.