Re: [Din] Minimal assumption for interoperable blockchain systems

Jon Crowcroft <Jon.Crowcroft@cl.cam.ac.uk> Wed, 06 June 2018 10:09 UTC

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From: Jon Crowcroft <Jon.Crowcroft@cl.cam.ac.uk>
To: Jon Crowcroft <Jon.Crowcroft@cl.cam.ac.uk>
cc: Thomas Hardjono <hardjono@mit.edu>, "din@irtf.org" <din@irtf.org>
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Comments: In-reply-to Jon Crowcroft <Jon.Crowcroft@cl.cam.ac.uk> message dated "Tue, 05 Jun 2018 15:01:45 +0100."
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Date: Wed, 06 Jun 2018 11:09:13 +0100
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Subject: Re: [Din] Minimal assumption for interoperable blockchain systems
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oh, plus you could have semantically equivalent blockchains, but
with different performance parameters, so we can sort those on tightness
of temporal bounds on consistency....but that's easy ...

for the stuff below, this might be useful:
https://arxiv.org/pdf/1707.01747.pdf

> strawman -
> 
> design a standard description for consistency algo used by each BC
> (there are some semi-formal ways of describing such algos...)
> 
> form a full interconnect of blochain systems and exchange
> descriptions which should form a partial order on the graph (guess)
> 
> compute which interconnects make sense and which ones cannot...
> 
> proceed....
> 
> > >>> From: crowcroft@gmail.com [crowcroft@gmail.com]
> > >>> ...
> > >>> so for inter-ledger type thinking, we're connecting systems
> > >>> that fundamentally care about consistency - but define its
> > >>> eventuality differently - so a basic building block of an
> > >>> interoperabilty or inter-domain protocol would be to
> > >>> convey (and somehow reconcile) that variation in notion
> > >>> of how long before we agree about an append in domain 1,
> > >>> when were' 5 ledger domain hops away...
> >
> >
> > Jon, this is excellent.
> >
> > I've been struggling to find words to use for what you refer to as
> > "consistency", particularly with regards to the end-state 
> ("eventuality").
> >
> > I'm assuming that at a high level, the "eventuality" is defined as some
> > data-string being recorded on the ledger of a BC (i.e. all distributed
> > P2P nodes of the BC).
> >
> > As you correctly intuited, the consistency-problem is more difficult for
> > cross-ledger transactions.
> >
> > A simple example with 1 entity only:  Alice wants to "move" her
> > registered land-deed from BC1 to BC2 (direct, no hops).
> >
> > -- How many transactions does Alice's Application need to transmit? (one
> > only to BC1; or one each to BC1 and BC2; or three: BC1; BC2 and then BC1
> > again).
> >
> > Any thoughts how how to define  "consistency" more specific/technically?
> >
> >
> > -- thomas --
> >
> >
> >
> > ________________________________________
> > From: crowcroft@gmail.com [crowcroft@gmail.com] on behalf of Jon
> > Crowcroft [jon.crowcroft@cl.cam.ac.uk]
> > Sent: Sunday, June 03, 2018 10:12 AM
> > To: Thomas Hardjono
> > Cc: din@irtf.org
> > Subject: Re: [Din] Minimal assumption for interoperable blockchain 
> systems
> >
> > looks sane (as did interledger) but we're missing (I think, but may be I
> > missed it too) one of the big challenges for this compared with scaling
> > (which is what you have to address in internetworking stuff whether
> > subnetworks with IP or IGPs with BGP, or serice+content with WWW - 
> that's
> > a fundamentally difficult piece of distributed ledgers- consistency
> >
> > one thing the e2e model did for thinking (amongst many) was to think in
> > an intensely relaxed way about consistency - IP doesn't care if the
> > source is still where it was when the packet reaches the destination (or
> > even first hop router. BGP doesn't care (much) about IGP convergance 
> when
> > announcing (or withdrawing) prefixes and (most) AS paths. WWW doesn't
> > care if the remote page (server, site or content) are there when you add
> > a URL to your site - all this is "fixed up later" by some eventual
> > consistency protocol (in IPs case, TCP;  in the IGP/BGPs case the
> > linkstate and path vector and a lot of magic pixie dust and luck; in the
> > WWW case, search/rank&shame and later maintenance) -
> >
> > so for inter-ledger type thinking, we're connecting systems that
> > fundamentally care about consistency - but define its eventuality
> > differently - so a basic building block of an interoperabilty or
> > inter-domain protocol would be to convey (and somehow reconcile) that
> > variation in notion of how long before we agree about an append in 
> domain
> > 1, when were' 5 ledger domain hops away...
> >
> > which reminds me, am I allowed to coin that term "ledgerdomain" ? :-)
> >
> > On Sun, Jun 3, 2018 at 2:51 PM, Thomas Hardjono
> > <hardjono@mit.edu<mailto:hardjono@mit.edu>> wrote:
> >
> > Here is a question I'd like to throw out to this community regarding
> > "interoperable blockchain systems" -- a topic which will undoubtedly 
> come
> > to the forefront (assuming it doesn't get drowned-out or killed by the
> > barrage of hype about BC):
> >
> > -- Minimal assumption: What is the minimal assumption for interoperable
> > blockchain systems with regards to the notion of transaction units. In
> > other words, what is the “datagram” equivalent of transactions –
> > namely the transaction unit that is semantically understandable
> > (processable) by multiple different blockchain systems.
> >
> > This is a question we posed in our recent discussion paper:
> >
> > https://arxiv.org/pdf/1805.05934.pdf
> >
> > Would love to get your thoughts on this "datagram" equivalent question
> > (or if this framework of thought is even the correct one).
> >
> >
> > Best
> >
> >
> > -- thomas --
> >
> > _______________________________________________
> > Din mailing list
> > Din@irtf.org<mailto:Din@irtf.org>
> > https://www.irtf.org/mailman/listinfo/din
> >
>