Hello Dan,

Electing a new master on a federation of internet services does not sounds a 
idea (at least extremely complex).
Several component can see at the same time that a service is down and elect 
themselves master on a given content, which can thus be distributed several 
times.
Many other problems can occurs, especially if you consider the internet link as 
not reliable. 

That's why I was thinking that the original question was more: "How to make 
content persistent on Fedone to avoid loosing waves" than actually how can we 
build a fully robust loosely coupled and distributed data and manipulation 
system.
Relying on each server building a reliable cluster deployment seems to be 
enough for me.

What could be a nice goal however is to allow read only access to wave that 
cannot currently be accessed, but that sounds conceptually easier.

-- 
Mickaël Rémond
 http://www.process-one.net

Le 29 janv. 2010 à 14:45, Dan Peterson a écrit :

> Agreed. This is an area I've been thinking about lately -- the electing a new 
> master scheme is appealing, but then what do you do when the original master 
> returns to the rest of the network (e.g. the uplink that was severed is 
> restored, then there'd be 2 servers that think they are master)? 
> 
> As an alternative scenario, I suppose the wave client UI could encourage a 
> "fork" of the wave conversation -- copying the latest version of the contents 
> into a new wavelet on the non-dead wave provider. Of course, forks are 
> effectively duplicate content, so not so ideal.
> 
> -Dan
> 
> On Sat, Jan 30, 2010 at 12:36 AM, Torben Weis <[email protected]> wrote:
> Hi,
> 
> I fear it is not as easy as assigning it to missing FedOne features.
> 
> If the master wave server breaks you need some other server to take over. But 
> the domain name of the broken server is encoded in the wavelet URIs which are 
> encoded (i.e. signed and hashed) inside the deltas. Thus, you cannot simply 
> replace the wave server without taking care of the cryptographic problems.
> 
> Even if this is dealt with, how do you efficiently vote on a new master 
> server? It must not happen that at any time there is doubt about the master 
> server (i.e. several clients deem different servers to be the master). Wave's 
> OT cannot handle such a scenario. There are peer-to-peer OT concepts which 
> can deal with it, but wave does not currently.
> 
> I think this is a really interesting research question, but the solution will 
> not be all too easy.
> This being said, even normal federation is complex enough :-)
> 
> Cheers
> Torben
> 
> 2010/1/29 Mickaël Rémond <[email protected]>
> 
> Hello,
> 
> Le 29 janv. 2010 à 13:17, chiang a écrit :
> 
> > Hi all,
> >
> > This could already have been a known deficiency in the federation
> > architecture, but I would like to enquire if it is by design that we
> > have authoritative or master wave servers for a particular wave? As
> > I've just found out that if the Fedone wave server (which hosts a
> > master copy of my initiating wave) goes down or losses all the waves,
> > the Fedone wave server does not recover the wave from wavesandbox,
> > which also has a copy of the wave. I initially thought wave servers
> > federation is supposed to be scalable, and resilient...
> 
> Fedone is an example implementation, not a production ready wave server. For 
> example, it still miss the storage engine, is not clustered etc.
> So this limitation is not by design but simply a not-yet-implemented feature.
> 
> Having an authoritative server for every wave seems a good and needed 
> approach for the Wave protocol itself.
> 
> --
> Mickaël Rémond
>  http://www.process-one.net/
> 
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