Re: [Gzz-commits] manuscripts/storm article.rst

[Benja Fallenstein]

address@hidden wrote:
> Quoting Benja Fallenstein <address@hidden>:
>
>
> > > > So the point of replication is that two systems always contain the same 
> > > > information, although there may be problems with this if conflicting 
> > > > updates have been made to the two systems (presumably used by different 
> > > > people). As I said, we want more things than that.
> > >
> > >
> > > Yes, partly true. Replication can happen between more than two systems
> >
> > (e.g. in
> >
> > > Notes) and the conflicting is a 'feature' of replication of the system
> > > (implementation issue as in Notes ;). Furthermore, term 'replication' is
> >
> > widely
> >
> > > used also in p2p research community, so it's not tied only to server
> >
> > architectures.
> >
> > It's used in a *completely different sense*, which is precisely one 
> > reason why I'm so opposed to it. Replication in the p2p community means 
> > mirroring for stability/accountability.
>
>
> Hm, in what way *completely different sense* ? 

In p2p, all replicas of a piece of data store exactly the same data 
(replication is for performance).

> As far as I have understood, the
> arcitecture is different to our case (client-server, p2p), but the goal remains
> the same; merge different versions of data, where data can reside in
> different locations,

No. P2P replicas are never intended to store different versions of data.

> so that we all have exact/identical copies of data.

Identical copies of data is a goal of p2p replicas (which is *not* 
archieved by merging versions in any system I know-- you cannot make a 
modification to a single replica, making a modification means updating 
*all* replicas, since they are supposed to be perfect copies, so there 
*can not* be versions to be merged on different replicas!). Identical 
copies of data are often not a goal in Storm.

> For p2p, indeed. I think term 'replication' is somehow misused.

I do not think so. I think the use in p2p is dead on :)

> But, my point
> was that term 'replication' is *not only used* in client-server environment.

And my point was that only the use in a client-server environment comes 
even close to what we want with Storm.

> > > > I have not been able to find a definition of 'synchronization'...
> > >
> > > Synchronization:
> > >
> > > > From Cambridge International Dictionary of English:
> >
> > Yeah, but none of these give the definition for our field, as far as I 
> > can see (that's why I didn't quote them). The question is: What does 
> > (data) synchronization mean in the computing field? Giving the 
> > 'ordinary' definition is rather like giving 'twig, slip' as the 
> > definition of 'clone' because that's the meaning of the Greek word 
> > 'clone' stems from :-)
>
> Perhaps we should some conclusions from it ?-) It's not used in our field, since
> it's not appriate ;).

Well, it *is* used-- google e.g. SyncML.

> To be serious, term 'sync*' has a strong relationship to *time*, which on the
> other hand, is not what we are interested in: "Now, because it's noon, we should
> synchronize our all blocks, since our meeting starts in one hour". 

I do not believe that the word sync, as used in the PDA field, is 
related to time as much. I do believe that the term 'replica' is 
strongly related to 'aim for always identical data,' which does not 
convey the correct image about Storm. I do agree that 'sync' may not be 
the best term, but for the same reason that I don't like 'replica,' just 
weaker-- 'sync,' too, conveys the image that we aim to keep the same 
data everywhere. I think it's the better term because it at least allows 
the idea that data may be 'out of sync.' Replica, by the very word, 
suggests that the data is always the same on all devices.

- Benja