3 ms·

Skype used to be a peer-to-peer application and did not use nor require any "central" servers. Then, Microsoft bought it and that all changed.

RachelF 10y ago
Skype claimed that the move to central servers was because peer-to-peer would not work on smartphones which were becoming their user base. The old Skype for Windows was really locked and obfuscated. I remember that it would not even start on my PC with a debugger installed, even though it was not running in the debugger.
Galanwe 10y ago
Disclaimer: ex Skype employee here While this simple reasoning is appealing, I have to disagree. Both its premises (Skype was peer to peer before MS) and conclusion (MS made it a client-server system because Evil). - Real peer to peer on internet is not really possible, since most end users are behind NAT. Skype resorts to a number of hole punching techniques, but really only uses STUN/ICE, effectively using super-nodes as relay for sessions. This directly means that all these communication are transiting through a third party, and not peer to peer. - Super-nodes used to be regular end users (with some simple algorithm to elect as supernode users with high up-time, high throughput. Fun fact: only windows client users were possible super-nodes). This model proved to be too fragile. In case the network falls down (which happened some years ago), then the super-nodes are no longer available, and get instantly DoS when coming back up due to every other node trying to get back. This is a vicious cycle in which the network cannot get back up. So for a long time now (before MS) super-nodes are just backed by Skype-hosted servers in data-centers. - Thin clients are a real thing in e.g. the african market, where a lot of very old phones are still in circulation, no "apps" are possible. Think of your old Nokia 3310. - Persistent group chats. Users wanted it. - And on a more "political" aspect: MS needed to promote its cloud infrastructure (Azure), lower its physical resources fingerprint (get rid of Skype datacenters), and unify its technical stack (Linux/C++ now Windows/C#)

RachelF 10y ago

Skype claimed that the move to central servers was because peer-to-peer would not work on smartphones which were becoming their user base. The old Skype for Windows was really locked and obfuscated. I remember that it would not even start on my PC with a debugger installed, even though it was not running in the debugger.

Galanwe 10y ago

Disclaimer: ex Skype employee here While this simple reasoning is appealing, I have to disagree. Both its premises (Skype was peer to peer before MS) and conclusion (MS made it a client-server system because Evil). - Real peer to peer on internet is not really possible, since most end users are behind NAT. Skype resorts to a number of hole punching techniques, but really only uses STUN/ICE, effectively using super-nodes as relay for sessions. This directly means that all these communication are transiting through a third party, and not peer to peer. - Super-nodes used to be regular end users (with some simple algorithm to elect as supernode users with high up-time, high throughput. Fun fact: only windows client users were possible super-nodes). This model proved to be too fragile. In case the network falls down (which happened some years ago), then the super-nodes are no longer available, and get instantly DoS when coming back up due to every other node trying to get back. This is a vicious cycle in which the network cannot get back up. So for a long time now (before MS) super-nodes are just backed by Skype-hosted servers in data-centers. - Thin clients are a real thing in e.g. the african market, where a lot of very old phones are still in circulation, no "apps" are possible. Think of your old Nokia 3310. - Persistent group chats. Users wanted it. - And on a more "political" aspect: MS needed to promote its cloud infrastructure (Azure), lower its physical resources fingerprint (get rid of Skype datacenters), and unify its technical stack (Linux/C++ now Windows/C#)