Re: [bitcoin-dev] Long-term vision for bitcoind (was libconsensus and bitcoin development process)

From: "Eric Lombrozo" <elombrozo@gmail•com>
To: "Jorge Timón" <jtimon@jtimon•cc>,
	"Wladimir J. van der Laan" <laanwj@gmail•com>
Cc: Bitcoin development mailing list <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Long-term vision for bitcoind (was libconsensus and bitcoin development process)
Date: Wed, 23 Sep 2015 00:07:22 +0000	[thread overview]
Message-ID: <em9a15c95a-cdb0-451f-8b69-e73572a722d2@platinum> (raw)
In-Reply-To: <CABm2gDrx4uDVPFL_tWUsvh_cN6qV903WCmgpA_Kj9Deq+Q3yfA@mail.gmail.com>

Here's what I propose as a long-term plan:

1) libconsensus
==========
We should probably start by defining an API for libconsensus. It should 
support an abstract DB model, track chain state, provide query 
mechanisms for blocks and transactions with optional pruning and 
indexing, expose a subscription mechanism for events such as NEW_TIP, 
REORG, etc, and contain a script interpreter.

We can develop the library in parallel with Bitcoin Core without too 
much refactoring of Bitcoin Core itself...just moving pieces of Bitcoin 
Core's consensus code into the new library, tracking code movements to 
make merging easier. Yes, this is a bit ugly as it requires code 
duplication...but it will temporarily avoid much of the downstream 
pushback we're getting. The idea is that we can prove out the library 
with some simple projects, then start removing the consensus stuff from 
Bitcoin Core once we have greater acceptance of the library and better 
documentation.

2) peer services
==========
We develop a peer services library that performs the tasks of peer 
discovery and relay, with the ability to connect to appropriate peers 
and queue messages. It uses libconsensus for all validation 
functionality and as a datastore for the consensus state but maintains 
its own database for peer history and statistics. I believe Cory has 
been working on this already using libevent. I've already developed an 
async library for this as well.

3) API/RPC
=======
We provide high level calls and pub/sub mechanisms. ZMQ has been 
implemented and added already, but we could support other transports as 
well.

4) Wallet
======
The wallet is split out into a separate process that connects to the 
stack via the API/RPC layer.

- Eric

------ Original Message ------
From: "Jorge Timón" <bitcoin-dev@lists•linuxfoundation.org>
To: "Wladimir J. van der Laan" <laanwj@gmail•com>
Cc: "Bitcoin development mailing list" 
<bitcoin-dev@lists•linuxfoundation.org>
Sent: 9/22/2015 11:36:14 AM
Subject: [bitcoin-dev] Long-term vision for bitcoind (was libconsensus 
and bitcoin development process)

>On Fri, Sep 18, 2015 at 2:07 AM, Wladimir J. van der Laan via
>bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote:
>>  My long-term vision of bitcoind is a P2P node with validation and 
>>blockchain store, with a couple of data sources that can be subscribed 
>>to or pulled from.
>
>I agree with this long term vision.
>Here's how I think it could happen:
>
>1) Libconsensus is completed and moved to a subtree (which has libsecp
>as an internal subtree)
>
>2) Bitcoind becomes a subtree of bitcoin-wallet (which has
>bitcoin-wallet and bitcoin-qt)
>
>Without aggressively changing it for this purpose, libconsensus should
>tend to become C, like libsecp, which is better for proving
>correctness.
>Hopefully at some point it won't take much to move to C.
>
>Upper layers should move to C++11
>
>Don't focus on the git subtrees, the basic architecture is bitcoin-qt
>on top of bitcoin-wallet, bitcoin-wallet on top of bitcoind (and
>friends like bitcoin-cli and bitcoin-tx), bitcoind on top of
>libconsensus on top of libsecp256k1.
>
>I believe this would maximize the number of people who can safely
>contribute to the project.
>I also believe this is the architecture most contributors have in mind
>for the long term, but I may be wrong about it.
>
>Criticisms to this plan?
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