Sunday, August 01, 2004


Until recently, instant messaging has been dominated by programs such as MSN Messenger and Yahoo Instant Messaging. Until about a year ago I didn't bother with such programs, believing that real mean use IRC, or possibly the UNIX "talk" program. However, about a year ago, I gave in and started using these programs. (For anyone who is interested, I can be reached as "" on MSN Messenger, and "mjj122" on Yahoo instant Messenger).

Both these programs are based on centralised servers. There is a centralised database of information about you, and this centralised information also includes a contact list. When you log on from any computer in the world, your contact list is loaded onto your computer and appears on your screen. The downside is that the owner of the system has a centralised database of information about you, and that if something goes wrong with the server, you are screwed. Also, for high bandwidth communication such as voice (which these instant messaging programs also offer) going through a central server is perhaps not ideal from an efficiency point of view.

Which is why people on the internet have taken to Skype in a big was recently. Skpe is sold as principally a voice communication tool, with instant messaging as a secondary feature whereas earlier services have sold it the other way round, but I think a better way of looking at it is that Skype is the same sort of application with two things changed: firstly it uses a far better audio codec so the quality of voice communication is much better; secondly it is not centralised but is instead peer to peer; (thirdly it is also encrypted end to end, and this is good, but I think it is less important as a selling point).

The peer to peer part is good from the point of efficiency and privacy, but it causes one little foible. Because there is no central server, your contacts list can only be stored locally on your hard disk. (Also because there is no central server, the information that you have gone on or off line takes longer to reach all your contacts, as it has to propagate around the network to them via a non-direct route, too. Again, this is important but less of an issue than the first). This means that if you log on to Skype from a computer other than your usual one, you do not have your contacts list with you. Personally I have thre Skype installations in this room with me now: one on a laptop, one on the Windows partition of my desktop, and a third on the Linux partition of my desktop. (Another good thing about Skype is that the people behind it have done a Linux version, for which they have my sincere thanks). These have contacts lists consisting of different subsets of my actual list of contacts. I am slightly concerned about logging onto each and adding the same set of contacts again, because I think it may annoy my friends if they are asked repeatedly if I may add them as a contact. (Actually, if Skype is well designed then they will not be asked again, but I am not sure if it is in this regard).

The Skype people claim they are working on a solution to this type of problem. Hopefully this does not involve going back to the whole idea of a central server, but I fear it may. Thems the breaks, I guess.

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