What does “Cloud Computing” mean to you?
There are enough jargons out there, and all you need is to select your favorite flavor of the day. On-demand computing, utility computing, and grid-computing have their own definitions that may stray into or may completely define cloud computing, depending on, of course, who is doing the definition. So, what is my definition for cloud computing?
In cloud computing, computing resources that scale to the needs of the deployed applications are provisioned and used on-demand from cloud computing vendors, and are paid for only when used.
I want to stress the pay-for-use (no long term contract), on-demand provisioning, and scalability of computing and storage resources. The pay-for-use is not exactly what some Enterprise users crave, especially those in the IT department. Enterprises like/want a host of things, and not having to do a contract can mean total disorientation in some Enterprises! I will take up on the perceptions of Enterprise in another blog entry.
Today cloud computing seems to be situated closer to S-a-a-S, as an enabler of SaaS on the one hand, and a platform for custom applications that anybody (Enterprise user wanted!) may write. No wonder, some folks prefer to call the entire cloud computing phenomena as a Platform-As-A-Service (P-a-a-S) movement. This is a very significant thing from the point of view of enterprise users, because it is no longer canned applications, but your own applications that are in the cloud! What does that mean? That is the big question to get an answer for.
The table below helps me to compare these in a truly apples to apples fashion.
|
|
Externally Hosted Applications |
S-a-a-S |
P-a-a-S |
|
Computing Resources |
External to enterprise |
External to enterprise |
External to enterprise |
|
Application |
Typically custom built for/by enterprise |
Prepackaged |
Custom-built/bring-your-own, or prepackaged |
|
Application Management |
Hosting provider, and/or enterprise |
SaaS provider |
Enterprise |
|
Contract |
Long term contract with SLA |
Long term contract, some with SLA |
No long term contract. Pay-for use. SLA is still nascent. |
The significant differences fall into two areas:
- who manages the application, and
- the contract
In PaaS vendor cannot really manage your application without owning the application itself which the enterprise created. So, the headaches of deploying and making sure the all the paths point to the right libraries, etc. never go away.
The next interesting question here is, what exactly can a PaaS vendor provide an SLA on. On the availability and performance of the application or the availablity and performance of the platform? If the later, then how is this contract different from a contract you would ave with an external hosted applications venodor?