What kind of service guarantees can I expect from PaaS?
Peter Laird wrote up a great analysis on Terms of Service for SaaS providers and it got me wondering: What about the emerging Platform as a Service providers?
They’ve got an especially difficult challenge because they’re running other people’s code. How do you ensure availability when it’s not your code? Google’s App Engine conspicuously avoids the problem by not providing any SLA.
Generally speaking, there seems be three categories of providers:
Infrastructure, managed hosting and run time environments: OpSource, Etelos, Joyent, AWS, GAE, etc Cloud IDEs: Bungee Labs, etc. App Builders: CogHead, LongJump, etc.
Obviously, the closer you get to bare metal, the harder it is for you to provide service guarantees.
I’ve already noted that AWS provides for 99.9% in their SLA, but that’s only for the service itself. Nowhere in that document does it say anything about your image’s uptime. Seems that you are on your own entirely.
This is a tricky problem even for the app builders. They all support some kind of scripting environment and you can only sandbox so much. Not to pick on CogHead, but I found this post on their forum. So, as you can see, these problems are going to show up everywhere.
I’d love to hear from anyone that has more details on SLA from platform providers.