[jdev] Semantic question
Dave Cridland
dave at cridland.net
Thu Apr 30 21:21:44 UTC 2015
On 30 April 2015 at 22:08, Goffi <goffi at goffi.org> wrote:
> 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 ?
>
>
Interesting thought.
We normally refer simply to "gatewaying". The term "gateway" was certainly
used for internet mail gateways to X.400, and for network gateways before
that, so it's pretty old.
The problem with "federation" is that it implies an equal basis, and I
don't think most IM gateways operate in that manner.
That's not to say, of course, that a "gateway" cannot be a form of
"federation" - many email gateways behaved in precisely that fashion,
exposing the whole of the SMTP federation to an X.400 domain, and
vice-versa.
>
>
> On 30/04/2015 12:54, Dave Cridland wrote:
>
>>
>>
>> On 30 April 2015 at 11:23, Goffi <goffi at goffi.org
>> <mailto:goffi at goffi.org>> 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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