Backup to the compute cloud

Many computer generations ago, Sun Microsystems adopted the slogan, "the network is the computer." There have been numerous cycles of computer buzzword since then but they are mostly just elaborations on that idea. "Grid computing" has been a popular buzzword in recent years, applied to a wide range of distributed computing configurations as I discussed in this article. Of the three categories of grid computing discussed in that article, cloud computing is most like a generalization of the "Space" concept as implemented in JavaSpaces.

The basic idea is that a user can get practically any computing task done with minimum investment in hardware or software by contracting with a service offered in the "cloud." The term is intentionally nebulous to convey the fact that the user does not care where or how the work is done, only that the results are correct. Services are used and paid for only as needed, a feature especially appreciated in businesses with occasional large peak loads.

Many trends have come together to create the possiblilty of cloud computing. I think the following play a major role:

• Virtualization of applications and operating systems tends to remove user concern about the underlying hardware and improves scalability.
• High speed networks remove concern about communication costs and delays, and permit location of hardware where electricity and cooling costs are minimal.
• Huge capacity/commodity storage devices, cheap generic computers and open source operating systems allow companies offering services to expand rapidly.
• RESTful web service design concepts simplify communication and client architecture.
• Big web enterprises like Google, Yahoo and Amazon have discovered that capabilities originally developed for internal support can be sold in the cloud.