Veteran virtualization blogger Alessandro Perilli of, whom I credit with unearthing most of the interesting goings on in the virtualization world, made an interesting observation that I validated the VMware platform strategy in a recent blog, observing that I had done a good job of developing a rationale for the VMware SpringSource acquisition.

It’s an interesting observation to be sure, but I’m going to vehemently stick with a response of “No I really didn’t”. For starters I didn’t even mention SpringSource in my blog. The goal of the blog was to show how the emergence of two kinds of clouds – IaaS and PaaS – give us indications as to the future evolution of the technology landscape. And also to point out that very substantial changes lie ahead for today’s OSes.

  • I argued that the case for IaaS clouds is basically the case for virtualization as a property of the infrastructure, and I stated that it is my belief that customers are now purchasing virtualized infrastructure independently of the OS(es) which they choose to develop/run their apps. I pointed to the emergence of virtual infrastructure platforms as entities independent of the OS, from all vendors, as evidence of the trend.
  • I also argued that the future of the traditional single-server centric notion of the OS as host of the application will be challenged. Again the evidence of this is the emergence of PaaS offerings from the major cloud vendors, most notably Microsoft, whose Azure platform indicates where Microsoft thinks the OS is going. There is other evidence too, which I hope to explain below.

Of course the PaaS concept, while extraordinarily powerful, is mostly about future apps. To develop future apps one needs lots of developers, and SpringSource and the Spring framework certainly have done a fabulous job of building a good developer base. But there’s an awful lot of work ahead for VMware to turn Spring into a PaaS platform, and to monetize it either with enterprises or as a cloud play. And as of now at least, it is restricted to Java apps. So if one wanted to point to a powerful PaaS platform that is relevant to a massive developer base, and that had the opportunity to address both today’s apps and those of tomorrow, Microsoft Azure would stand head and shoulders above the rest. My case for the future of the OS was really a case for the emergence of something like Azure – something that can run today’s apps (as VMs) and tomorrow’s (on the “next OS” platform).

Now, with my “everything that is relevant today is already legacy” hat on, I want to make the case for the emergence of a PaaS (or application-centric) approach as a logical evolution of the IaaS model, for which again I see strong evidence on the part of major players, including VMware. This also challenges the traditional role of the OS. Here is what is happening:

  1. The major IaaS vendors are already adding PaaS-like features: One has simply to observe the rapid and continual evolution of the IaaS model and the offerings from vendors to see that the bare-bones Virtual Private Server model is rapidly being enriched with features that are very developer and app sticky. While VMware boasts about its 2M Spring developers, Amazon Web Services can boast at least half a million. And there’s a very significant difference between the two: The AWS apps are built around a monetization model, from the get-go. So with Spring VMware will likely compete head to head with both IaaS and PaaS cloud providers, including Azure. If Spring and its hosted apps are run and monetized on top of IaaS clouds and offered in their own right as SaaS apps to customers, then VMware will find that it competes with another category of vendors: the software resellers – the same folk who happily sell vSphere today.
  2. Emerging standards, such as DMTF OVF, will allow IaaS clouds to become more app-centric: The vendors who work on standards at the DMTF, including all of the virtualization players, have collaborated to develop a portable application packaging standard, called the Open Virtualization Format (OVF). Citrix Project Kensho offers a complete open source toolset for the OVF, including the ability to combine in a single portable package multiple VMs from VMware, Xen/XenServer, & Hyper-V, together with all of the meta data required to completely instantiate multiple VMs and all of their environmental configuration, on any virtualization platform. OVF provides a powerful framework for packaging complete multi-tier applications, combining VMs in any OSes, their storage, compute, networking and other parameters. OVFs can be secured, and readily imported into IaaS clouds where they can be instantiated and run. Here the traditional OS plays an important role – namely running specific components of a multi-tier, multi-VM application. But that’s it. Adoption of OVF by IaaS clouds as their standardized import/export format will give them an ability to directly deploy and ultimately manage the life-cycle of applications for their customers – hence becoming more app-centric. In this model the VM is simply an execution container for a part of an app.

Finally for those of the “traditional OS wins” variety who took offense to my last blog: There is no doubt that virtual infrastructure is compelling from an infrastructural agility, availability and resource management perspective. But the “VM as proxy for the app” model (which is how most virtualization administrators manage their environments today) is simply a recognition that most apps run in one VM, and hence the relevance of the OS is uncontested – from the app perspective. Moreover the skill sets and processes of today’s IT Pros mean that the “single app per OS / VM” will remain a key building block of enterprise IT for a very long time. Indeed one can argue that the change to an app model that inherently spans multiple virtualized execution containers is so profound that it is generational – and will occur only as fast as skill sets evolve in IT. But I’ve been surprised by how rapidly the cloud has seized attention in corporate IT, perhaps because it is so much easier to consume IT as a service than to stand it up oneself, and so much more productive to develop new apps using powerful new frameworks. Indeed one can postulate an outcome whereby traditional IT enterprise architectures and growth will stall, in favor of new deployments using private and public service offerings. IaaS cloud providers are moving up-stack to support abstractions for apps and the momentum around PaaS (or even enriched IaaS) is a telling indication of the trends.