Date: Sun, 21 Jul 2013 17:55:14 +0200
From: Pieter Wuille <pieter.wuille@gmail.com>
To: Mike Hearn <mike@plan99.net>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>,
	Jonas Schnelli <jonas.schnelli@include7.ch>
Subject: Re: [Bitcoin-development] Introducing BitcoinKit.framework
Precedence: list

On Tue, Jul 16, 2013 at 12:59:56PM +0200, Mike Hearn wrote:
> I think that's a great approach. Here is the patch Satoshi sent me back in
> 2010. All the code has changed since but it can be a source of inspiration.
> 
> >From Satoshi:
> 
> *The simplified payment verification in the paper imagined you would
> receive transactions directly, as with sending to IP address which nobody
> uses, or a node would index all transactions by public key and you could
> download them like downloading mail from a mail server.

I'm currently working on headers-first sync, which I believe is generally
very useful (it fixes tons of edge-cases block synchronization currently
experiences), but it's also a first step towards SPV mode.

So headers-first sync means you first synchronize just the headers, and then,
when you already know (or have strong evidence for a guess on) the best chain,
start requesting blocks along that best chain - potentially in parallel from
different peers.

SPV mode is basically headers-first sync, but never do the full block sync
step, and replace it with a bloom/birthday/...-based fetching of blocks
interesting to the associated wallets. In SPV you'll also need to disable
the mempool though, and there will be more small changes, but I think
the separate headers-sync phase will be most of the work.

-- 
Pieter