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Dawn Levy, News Service (650) 725-1944; e-mail:

Mobilized messages catch people on the go

The answering machine picks up on the third ring. You don't want to leave yet another voice mail message, so you slam down the phone and stare morosely at your address book. Pager, cell phone, work phone, e-mail which should you try next?

There's hope for the frustrated. Researchers in the lab of Mary Baker are figuring out how to ferry messages directly between people by using a computer program that determines the right way to deliver the information to the recipient.

"My mom used to complain all the time, 'I have your home phone, your work phone, your cell phone. You've given me all these numbers, but how do I get a hold of you?'" said Baker, assistant professor of computer science and electrical engineering.

To single out the most efficient way to contact someone, Baker's research group designed a "personal proxy" a software butler that takes incoming messages, figures out where you are and sends the message to your actual location by the appropriate medium, be it phone, e-mail or pager.

Baker became interested in the idea of communication between mobile people after completing a wireless notebook project in 1997. The group had developed software that allows laptop computers to switch between regional wireless and wired networks and still remain plugged into the Internet.

"We solved the problem we set out to solve," Baker said, "but we decided that it's really the people who are the endpoints, not the devices." Information might reach a computer on a boat or in a cow pasture, but that doesn't mean the recipient was tapping away at the keyboard when the message arrived.

Ideally, you'd want the proxy to pick up your location automatically. The group's prototype notices when a laptop wakes up or when an office PC's screensaver switches off. Cell phones present a trickier problem at the moment, you need to tell the proxy when your phone is on. "We're in the process of adding more features and getting ready to deploy [the proxy] on a small scale," Baker said.

All this access seems to call up a specter of privacy invasion. But Baker counters that this isn't the case one of the primary goals of the project is to increase the user's privacy. Normally, the message-sender is the one who calls the shots he or she decides when to pick up the phone or dash off the e-mail.

"We want to give the recipients more control than they've had in the past," Baker said. People could program the proxy to put messages through at designated times. Coffee can be savored interruption-free or, Baker said, "you can define a rule that says, 'I don't want to hear from my boss after two.'"

Critical messages still can get through, Baker said. "I might create a rule that only sends stuff to my pager if it's from the daycare. If my daughter's fallen off the jungle gym, I need to be there."

Security also can be a concern. A personal proxy "knows" a lot about your location and habits. The information could be exploited; for example, an abusive husband might hack into the proxy and retrieve information on where his wife had flown.

To minimize this possibility, the proxy software is first installed in a trusted location, either the Internet service provider or the user's home computer, if that's secure enough. Passwords and other authentication are required to change the rules for the proxy.

Right now, Baker's group is focused on creating a novel identification system anyone could use to contact your personal proxy. Forget handing out e-mail addresses and phone numbers why not just give a new friend an easy-to-remember and unique name?

Baker and her group found that a set of five words something like "Snow White, Tidy Dwarf Groupie" would provide enough unique word sets to serve many people.

But there's a hidden problem in this mix: How do you know that a particular set of words corresponds to the person you think it does? Identity is fluid in the constantly shifting Internet, where e-mail aliases and addresses pop in and out of existence. Somehow, the word sets need to be authenticated and updated.

Baker's group members think they've found the answer. They suspect the solution is a history server, a reference database that tracks online personalities through time. "The history service would provide authentication," Baker said. "It's a time-stamp nobody else could claim to be so-and-so during a certain time."

Lose track of a friend? If you have his or her old e-mail address and a date when it was active, Baker's technology could retrieve his or her word set and build a bridge to the past.


By Katie Greene

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