The Computer for the 21 st Century Mark

The Computer for the 21 st Century Mark Weiser – XEROX PARC Presented By: Mihail Ionescu

Outline • Brief presentation of the paper • What happened in these 10 years in this domain since the paper was published • Conclusions

Motivation • The best technologies are those that disappear. • Writing is the best example it is almost invisible for us in the sense that it is used almost without realizing it. • Possessing the most powerful computer is like having just one book, does not matter how big it is. • Also, the computer screen demands full attention.

Contributions • Not real technical contributions, since it is not a technical paper. • One of the first (if not The first) papers that try argue for the need that the silicon technology should “vanish in the background”. • Some real life scenarios of using this paradigm. • Identity the technical requirements of an infrastructure for supporting the ubiquitous computing.

Ubiquitous Computing • The computers will be everywhere: pens, cans, pads, boards, coffee machines, alarm watches, etc. • Some of the devices (like traffic lights, ovens, etc. ) already have computers incorporated, but without the possibility of communicating between each other, which is very important. • At least hundreds of components in each room. • Electronic badges are already in use (I think). • Current prototypes to build pads, tabs.

Technical Requirements • Three main parts – Cheap, low-power computers that include convenient displays – A network to tie them together – Software systems to implement ubiquitous applications

Low-power Computers • The first requirement is not so difficult to be met • Even at the time when the paper was written such devices existed • Today there are such devices with processors of 200 MHz (maybe more), RAM of 128 M and even color displays • The devices should be simple, no AI or other complex technologies

Network • Data transmission rates for both wired and wireless networks are increasing. • The current systems cannot (and will not) support hundreds of machines per room. • Three types of network connections: tiny range wireless, long range wireless and very high speed wired it is a need of a single kind of network connection that somehow serve all three functions.

Applications • New operating system idea that does not assume a relatively fixed configuration of hardware and software. • New systems that have to deal with the diversity of inputs from the user.

What Happened in 10 Years • Almost nothing that was described in the paper (even if Weiser predicted 20 years). • The devices are here, maybe more powerful that Weiser imagined. • However, the network does not exist in the generality imagined by Weiser. • Many of the devices contain computers, but the computers do not communicate in a “ubiquitous” way.

Why? • I think that mainly because what Weiser suggested is not practical nor possible. • The second requirement (the network part) is much more complex than initially thought.

Technical Problems • It is not clear whether this network will be based on the current Internet infrastructure (IP based), or it will require a new, completely different approaches. • Even much smaller ad-hoc networks could not use IP as the based protocol new protocols like Blue Tooth, etc. • New schemes of routing: content based, smart messages, etc.

Other Problems • Security would become a nightmare. The idea that cryptographic techniques will solve this problem is a joke. • Flexibility.

Conclusions • A good starting paper, that tries to present what ubiquitous computing is and how it can be used. • However, the paper suggests more that this idea is not practical and extremely difficult to implement in a robust manner. • Low power computers exist and will be used in a lot of devices, but not in a global network. • Some much narrow projects might benefit from low power computers communicating between each other, like sensor networks.