[scofalik]

> OT is very simple to implement, but needs a server (...)

Well, OT in general does not need the server but server-less implementations are more complex (more transforming functions to write, except of "inclusion transformation" you also have to write "exclusion transformation" algorithms).

I also wouldn't say that "OT is very simple to implement" - it is in it's base form, for linear data, with the server in the network. But every enhancement brings a lot of complexity.

[z3t4]

On a work "test" I was asked to write a diff function (least amount of transformation to get from one state to another state) from scratch, even though I've read many diff-algorithm-papers in my life I couldn't actually implement one (even though I got 99/100 tests right, they failed me with the feedback that I need to work on my algorithms ... ). But after getting the concept of OT it was straight forward to implement it from scratch. That's my relativity, maybe someone else think it's easier to implement a diff algorithm.

If two clients, your client (a) and another client (b), writes the letters a and b respectively at the same time, from either client's perspective they where first, so on client A the state will be "ab" and on client B the state will be "ba". How do you solve that without a server/master ? With a server/master the server just have to increment a counter for each operation, and the clients can use that counter to know which order. So if a has counter 77, and b has counter 76, the state will be "ba".