IaaS vs PaaS

For a very long time, I had regarded platform-as-a-service (PaaS) as a catch-all bucket for everything cloudy that was not software delivered over Internet on demand (SaaS) or infrastructure (IaaS). Over the past several months however, with announcement of new players in PaaS space such as CloudFoundry and OpenShift, I found myself thinking about PaaS in a new light.

PaaS currently seems to be converging on a concept that is essentially an expanded application server (typical examples of application servers are Tomcat, Weblogic, Websphere, Glassfish, JBoss etc). You package your web application in a certain way and upload it to the server. Server then sets up the environment (such as, for example, your database connection pools) and runs your app.

PaaS of course adds a few twists (examples of functionality that PaaS could offer include multitenancy, autoscaling, API, off-premises hosting, multi-language) but fundamentally it essentially feels to me like a glorified application server.

Several observations.

Firstly, every big software vendor seems to have at least one product in its current lineup that in some shape or form fits into the application server space. I expect each of these vendors to repackage their offerings into a PaaS or PaaS-like product - the more the merrier.

Secondly, the more I think about it, the more I become convinced that a private PaaS will dominate private IaaS at enterprises for applications developed in-house. If a company adopts one of the application servers today as an internal standard, it simply makes no sense to allow internal development of any applications that would not run on them.

Thirdly, you gotta hand it to Google - when everyone was crazy about a cloud model popularized by Amazon EC2, they didn’t cave in and didn’t start offering low-level OS VMs. They have focused on language VMs (Python VM, JVM) and up since the very beginning - this looks exactly what PaaS has become now. In their latest release, they added backends for long-running background processes (in other words, all daemons that do not fit HTTP request-response model). I expect other PaaS implementations to follow suit.

Fourthly (as a direct consequence of points #2 and #3 above), I now think that private IaaS clouds will become a place where enterprises run their vendor-supplied (possibly closed-source) non-web-based workloads. As a result, software vendors will need to adopt new ways how they distribute their software. There will be no need to do installers and try to detect a machine’s hardware and OS. All software can be shipped as a VM image (with or without customer access, or maybe just partial customer access).

And finally, I am now convinced that today’s PaaS moniker should become application server as a service. Or - to make the acronym easier to pronounce - a webapp container as a service (WCaaS or ACaaS). There is simply too much “platform” beyond an application server use case - think data store as a service, messaging bus as a service, external connectivity as a service, load balancing as a service, naming as a service, and so on. Each of these could be a standalone service.

Good times for cloud computing!