23/08/07
Skype crashed worldwide on August 16th
This is garnet stone's guess as to the cause:- his post at 18.39 on August 17th.
Skype's official reply:-
Skype's report:- look for "What happened on August 16" posted on August 20th.
Essentially there was a domino effect as supernode servers crashed, putting more load on other supernodes which then crashed, causing meltdown for the whole system.
Skype's official report differs from garnet stone's guess, but there may be some connection between them.
Skype said that Microsoft's automatic update caused millions of computers to restart at the same time. Millions of those (Skype usually has 300 million users online at any time) would have had Skype set to automatic login, so they tried to log in to Skype at the same time. This overloaded some supernodes which crashed.
The supernodes that crashed would have had other Skype users logged in besides those that were getting Microsoft automatic updates, so those extra Skype users like me and my neighbour also started trying to log in to Skype automatically.
The Skype login attempts were transferred to other supernodes, which also crashed until the whole peer to peer network was down and all Skype programs were continually trying to log in every few seconds.
The problem for Skype was then to start up a decentralised system when 300 million Skype programs were continually attempting to log in. Apparently Skype has some algorithms in the program on our computers which was designed to control this but a bug had lain hidden for years in all previous programs.
Skype say that this has been corrected in the version 3.5.0.214 issued after the crash but time will tell if it stops another similar situation.
Somehow Skype managed a gradual rebooting of supernodes and Skype programs started logging in after two days.
Supernodes aren't directly under the control of Skype; it seems that Skype identifies servers or computers using Skype which have large and continuously available bandwidth and uses them as supernodes (all users agree to being used but obviously personal computers without much bandwidth which are turned off quite often would never qualify). It seems that servers of major institutions are used, presumably with some kind of tacit agreement, as Skype is beneficial to them as it saves landline call charges.
06/09/07
MeBeam video conference program is now beta
The Videobox of May 2007 has now become a program which can be used for conference calls between eight people and also for playing back the calls or leaving messages if the room name chosen by the callers includes a $ prefix so that anyone who knows the room name can view the videos later as a continuous discussion involving all callers and it skips on to the next call if there are several calls using the same room name.
The program has an inbuilt facility for eighteen callers which may be activated later. At present the bandwidth is limited by showing the video images in different size windows depending on the number of callers; two videos are large, three slightly smaller, four half the size of the original two in one row across the top, another row across the bottom if there are eight callers. I presume eighteen callers would be three rows of six.
See MeBeam Multivideo and MeBeam - my recorded room
The original WigiWigi programs started about two years ago were P2P and callers needed to know the IP address of their contacts to call them. The MeBeam version is coded in Flash and server-based.
26/09/07
Visitors to my online XHTML & CSS tutorial
I checked my website statistics to find that overnight and this morning the following three organisations had downloaded pages from my online tutorial.
128.30.52.49
Massachusetts Institute of Technology
MIT Laboratory for Computer Science
Room W92-190
77 Massachusetts Avenue
Cambridge
MA
PostalCode: 02139-4307
US
150.125.32.94
Space and Naval Warfare Command
5 Crystal Park
2451 Crystal Drive
Arlington
VA
PostalCode: 22245-5200
US
74.6.20.214
Inktomi Corporation
701 First Ave
Sunnyvale
CA
PostalCode: 94089
US
"Inktomi developed and marketed scalable software applications designed to enhance the performance and intelligence of large-scale networks."
I can't believe that any of the above large corporations would need help from my tutorial; perhaps it was just an employee wanting help for his own personal web page or some kind of snooping, though these corporations aren't known for trawling the net as far as I know.
26/09/07
A biking companion?
I haven't been so lucky yet when out over the hills on farm tracks and footpaths.
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