Benny Rochwerger started his presentation with the example of Internet radio that has some similarities with Clouds. Internet radio stations do not have to install the whole broadcasting infrastructure themselves, but rent it from some infrastructure provider that supports many Internet radio stations.

This means that It does not take much effort to set up an Internet radio station and the station owners only have to take care of the content. Creating and maintaining the infrastructure to support the stations is currently done by a few large companies.

The Cloud - public Cloud - is somehow similar in that a few large infrastructure providers allow many people to use Infrastructure as a Service. This allows democratization of resources.

Cloud computing is now possible because of the experience people have gained with distributed services like Internet radio and adoption of Software as a Service. What has also become available recently is broadband networks and virtualisation techniques for Intel architectures.

Does not this sound like Grid? Perhaps it is similar, but Benny Rochwerger sees some differences.

He sees Grids as taking care that highly specialized resources can be shared by many users. Grids are in general about large data sets. Another important aspect of Grids is that they are used by users who want to share resources. In many cases, Grid users are also Grid resources owners. Interoperability is hence available by design.

Clouds on the other hand are much more driven by business demands like reducing CAPEX, OPEX, or time to market. Clouds can be used by millions of people who get a share of the available resources. However, they share because they want to save money, not because they want to share.

There are a few very large providers of Cloud based infrastructures. All though they provide similar services, they are not interoperable. So essentially you have the risk of vendor lock-in. The only way out of this is standards. But this is not in the interest of the vendors, so it has to be driven by the customers.

Benny Rochwerger expects that once the standards are there, there will be an eco-system where you will have local Clouds within a company, partner Clouds with companies you trust, and public Clouds that you trust less but which are inexpensive. Cloud standards allow you to seamlessly move from one Cloud to the other.

Within the European Reservoir project (http://reservoir-fp7.eu) - of which Benny Rochwerger is a member - they are exploring the Cloud computing possibilities.

The team has identified the following pillars of Cloud computing:

• Separation: Cloud computing providers lease resources on pay-per-use basis but do not expose infrastructure details to customers or partners
• Isolation: Given the hosting nature of Cloud computing providers, consumers need mechanisms and warranties that their applications are isolated from others that are being hosted in the same infrastructure
• Elasticity: When the computing demand increases or decreases, the required computing resources should be instantly increased or decreased.
• Federation: Perhaps the most important pillar because it must be possible to combine resources from different Clouds.