Cloud = Web?

Sam Johnston has written an interesting blog article in which he presents his definition of Cloud computing:

Cloud Computing is the realisation of Internet (‘Cloud’) based development and use of computer technology (‘Computing’) delivered by an ecosystem of providers.

I think, Sam made some valid points. It is important to say that by cloud people usually mean a computer network, namely the Internet. The term should be used with this meaning (and I confess: I did misuse the term).

In my first classification pictures I had the core of the cloud named “Infrastructure as a Service”. I do not like the *aaS inflation, so I changed it to “cloud”, which is even more dubious. Perhaps “Infrastructure as a Service” is not such a bad term after all.

OK, I agree with you, Sam. What about the other terms, Cloud computing, Utility computing and Grid computing?

I have a bit of a different view regarding “Cloud computing”. I think that EC2 and S3 are something like Cloud computing reference models. It is about virtualized resources (Virtualization), it is about accessing these resources as services (Web Service), metering is done per-use & pay-as-you-go (Utility computing).

The difference between Cloud computing and Grid computing is more subtle. I am currently reading a couple of good papers on “Grid Economics and Business Models” [If you click the link and buy the book I will get ad payments. If you don't want this to happen, don't click.]

Grid Economics and Business Models: 4th International Workshop, GECON 2007, Rennes, France, August 28, 2007, Proceedings (Lecture Notes in Computer Science)

The Grid computing community has worked out a lot of pretty good ideas and tools. I wonder why the attention has been drawn from Grid to Cloud. The main differences between Grid computing and Cloud computing I can see so far are:

• Cloud computing gives access to virtualized resources in a typical Web hosting way (look at EC2, Joyent, Mosso, …). This is nice for people used to classical Web hosting (developers). Interfaces are developer-friendly (root access, REST/HTTP/SOAP/BitTorrent).
• The Cloud computing backend is formed by huge data centers, whereas Grid computing is more about sharing resources between organizations (Virtual Organization, VO). Some people describe Cloud computing as the evolution/revolution of data centers. Setting up a VO might be one of the key problems: network externalities are good if you can pass the critical mass but bad if you don’t.
• Big players like Amazon, Google, IBM, and so on are pushing the Cloud computing topic. I am not sure if it is all about resource utilization but data center consolidation might be a driver.

However, more thoughts should be dedicated to this topic.

A last remark: is there something like a private cloud or internal cloud? Maybe this should be seen as an overlay network, like VPN. If it is installed behind a firewall I tend to agree with you, then it is a grid.

Sam, thank you for the interesting discussion!