Thanks for you answer Dave (and Adrien),
So we can talk about federation for different protocol (if I add a
gateway to my server, I add a federation with the legacy network), right ?
On 30/04/2015 12:54, Dave Cridland wrote:
On 30 April 2015 at 11:23, Goffi <[email protected]
<mailto:[email protected]>> wrote:
G'day,
for years I have used decentralised, distributed, and federated
with, in my head, the following meaning:
- decentralised: the ability to have several servers
communicating together, the servers can be under the same domain
(example.net <http://example.net> can have several servers)
By "decentralised", I really just mean it has no centre - there aren't
any special, or especially privileged, servers.
XMPP fits this description, but not all services built on XMPP do - for
example, if we had a single user directory (and I think one such did
exist at one point) that would be a centralised service.
Matrix has identity servers, which are a centralised trusted naming
service, DNS is similarly centralised (due to the root service).
In neither case are the "centralised" servers a single entity; they're
just a privileged set, providing a distributed service.
Of course, these all assume actual servers, and a service defined in
terms of a simple protocol. For a particularly odd example, consider
PKIX, where we have multiple, fully independent, Certification
Authorities forming a heterogeneous privileged set of providers - PKIX
is clearly not decentralised, but has multiple central points...
- distributed: 1 server = 1 user, no intermediate (not even
DNS, so XMPP is not distributed according to this definition, but
something like retroshare is)
Your definition fits what people tend to mean by "peer to peer",
although s/user/device/.
Almost anything can be described as distributed.
It might mean a service which is available equivalently at multiple
points on the network. Which really doesn't say anything useful.
It might mean a service which is provided equivalently by multiple
points on the network; that's a slightly tighter definition, but covers
clustered XMPP servers, for example.
I suspect people usually intend to mean a service which is provided
equivalently by a decentralized set of providers, and in extremis they
can mean peer to peer.
Well, no.
People usually seem to mean "whatever it is that we do", and use it
liberally on marketing brochures.
- federated: the ability from servers of different domains
(example.net <http://example.net> and capulet.lit) to talk together,
in both directions.
Yes, or more generally, the ability for multiple disparate
administrative domains to intercommunicate on an equal basis.
But after a talk I realise that the definitions accepted is not the
same everywhere, e.g. Diaspora people talk about federation for what
I call decentralisation. Actualy it's a bit tricky, because if one
entity has 1000 servers but everybody is using the same domain, the
data are centralised in the hands of the same entity.
So, what meaning do you put behind these words ? Are
decentralisation and federation more or less synonyms ?
Sorry to put this on jdev@, I was not sure of which mailing list to
use :)
Goffi
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