and applications—all living in a browser window. Another solution would bypass the Web browser, substituting a more-capable software system that runs as a separate application on the client computer and communicates directly with servers in the cloud. This is the idea behind AIR (formerly Apollo) being tested by Adobe Systems. Open-Laszlo, an open-source project, works in much the same way.

For those deploying software out in the cloud, scalability is a major issue— the need to marshal resources in such a way that a program continues running smoothly even as the number of users grows. It’s not just that servers must respond to hundreds or thousands of requests per second; the system must also coordinate information coming from multiple sources, not all of which are under the control of the same organization. The pattern of communication is many-to-many, with each server talking to multiple clients and each client invoking programs on multiple servers.

The other end of the cloud-comput-ing transaction—the browser-based user interface—presents challenges of another kind. The familiar window-and-menu layer of modern operating systems has been fine-tuned over decades to meet user needs and expectations. Duplicating this functionality inside a Web browser is a considerable feat. Moreover, it has to be done in a comparatively impoverished development environment. A programmer creating a desktop application for Windows or one of the Unix variants can choose from a broad array of programming languages, code libraries, and application frameworks; major parts of the user interface can be assembled from pre-built components. The equivalent scaffolding for the Web computing platform is much more primitive.

A major challenge of moving applications to the cloud is the need to master multiple languages and operating environments. In many cloud applications a back-end process relies on a relational database, so part of the code is written in SQL or other query language. On the client side, program logic is likely to be implemented in JavaScript embedded within HTML documents. Standing between the database and the client is a server application that might be written in a scripting language (such

as PHP, Java, and Python). Information exchanged between the various layers is likely to be encoded in some variation of XML.

Even though the new model of remote computing seems to reverse the 1980s “liberation” movement that gave individual users custody over programs and data, the shift does not necessarily restore control to managers in the corporate IT department.

To the extent that cloud computing succeeds, it represents an obvious competitive challenge to vendors of shrink-wrap software. Ironically, the open-source movement could also have a tough time adapting to the new computing model. It’s one thing to create and distribute an open-source word processor competing with Microsoft Word; not so obvious is how a consortium of volunteers would create a Web service to compete with Google Docs.

Finally, cloud computing raises questions about privacy, security, and reliability—a major subject of discussion at a workshop held last January at the Center for Information Technology Policy at Princeton University. Allowing a third-party service to take custody of personal documents raises awkward questions about control and ownership: If you move to a competing service provider, can you take your data with you? Could you lose access to your documents if you fail to pay your bill? Do you have the power to expunge documents that are no longer wanted?

The issues of privacy and confidentiality are equally perplexing. In one frequently cited scenario, a government agency presents a subpoena or search warrant to the third party that has possession of your data. If you had retained physical custody, you might still have been compelled to surrender the information, but at least you would have been able to decide for yourself whether or not to contest the order. The third-party service is presumably less likely to go to court on your behalf. In some circumstances you might not even be informed that your documents have been released. It seems likely that much of the world’s digital information will be living in the clouds long before such questions are resolved.

 

Brian hayes writes about science and technology from Durham, NC.

Virtual Reality

A Fly’s Life

A team of Swiss and U.S. researchers have developed an interactive virtual-reality display system that enables them to better understand fruit flies’ behavior and movement in response to their visual environment, New Scientist reports.

Led by Steven Fry of the Institute of Neuroinformatics in Zurich, the Swiss-U.S. team built a wind tunnel in which changing scenes or images are projected onto its walls. A camera tracks a fruit fly in 3D, making the scenes or images move in response to the animal’s activity inside the wind tunnel. Previous research had involved tethered flies which, Fry said, “is very unnatural and it becomes very difficult to interpret the data because of the strong interference by the experimenter.”

The team’s research, which has implications for animal behavior and biomimetic design control, can be readily reproduced, according to Fry. “Being based on standard hardware and software techniques, our methods provide an affordable, easy to replicate, and general solution for a broad range of behavioral applications in freely moving animals,” he says.

Information Technology
Wireless
Conductor
Paths?

The conductor paths in sensor systems have traditionally consisted of thin wires—until now. Researchers at the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research in Bremen, Germany, have developed a new technique that prints conductor paths, using a contactless aerosol ink with nano-sized silver particles. In tests conducted with the Institute for Microsensors, Actuators and Systems at the University of Bremen, the printed conductor paths have proven to be nearly 500 times thinner than wire bonds, and the sensors provide significantly more accurate measurements.