13 Mar 2013, 20:38

A tale of two PaaSes

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I spend a good amount of time trying to figure out if my operational team can do much to make the general engineering efforts more productive. We’ve followed the usual turns around self-service IaaS and the like, and we’re now exploring the next level of Platforms-as-a-Service. In exploring the options, I’m seeing two large patterns.

On one hand, there are the “middleware centric and injection based” PaaS models. These are the ones where the developer picks a development middleware (Java Servlet, PHP, Node, Rails, etc), and adds other parts in. As if by an after thought, a static file service is added, or maybe a data persistance (i.e. database) service is added. On a implementation level, these usually involve allocating some compute and storage resource (e.g. a VM), installing the middleware container, doing a baseline install of the add-ons, and starting them all up inside that VM. There are some other configuration items such as pointing it at some version control repository, but also the developer is able to login onto the VM via shell.

On another hand, there’s a “service focused” PaaS model. This feels like the lesser named PaaS, though it probably has a larger install because this is the model that AWS largely is. In this case, the developer picks different service components (e.g. DB, cache, messaging bus, etc) and composites them a bit more independently. Underneath the control layer, each of the component providers can implement their services in different ways - using different VMs, processes, or internal containers (e.g. DB schemas w/ authnz) - based on what makes sense for that provider. There’s more work for the developer here as they have to compose services across different providers, and the developer doesn’t have direct access to the underlying system, but in exchange, might have better options.

From an implementor’s perspective, I think the service focused model is easier to maintain. This may not necessarily be the right reason to go down that route, but when it comes to delivery, that matters a lot. It’s also a bit more transportable - at this point in the industry’s lifecycle, it’d be easier to migrate from one IaaS or traditional Infrastructure to another. It’s also easier to extend this model to other (traditional?) services such as monitoring. You can see this in the industry - there’s many different service providers focusing on a narrow niche offering around one specific service, but fewer middleware centric vendors and even those that exist tend to also include some service based model for the add-ons.

As I said, most of the traditional services called PaaS are the form. So, what makes the application middleware so much different than a data store? or a caching layer? Fundamentally, you have some level of “service” which you want to present a clean interface to. This is true for the database as well as for a java servlet container, yet somehow we treat them a little differently in our heads. The only reason I can imagine is that is where time is spent. As a developer, I spend most of my time in the code, so that’s where my mind goes. But while I run it, I want to have a better idea of how it fits in with the other component services.

I think the vote is still out on which way has better long term viability. And it may never be decided on. It may just be a matter of preference.

Maybe PaaS isn’t the right term for this second model. These are more Services-as-a-Service, which seems likely to be a great way to confuse people. Mmaybe they’re more along the lines of Infrastructure, and are just a different take on that. I’ll admit, I’m not sure what the right way to refer to them is, but I believe that the use case that they present is more than just an implementor’s fancy. It’s a valid use case based on how developers are expecting to work with it.