Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com
	designates 74.125.82.53 as permitted sender)
	client-ip=74.125.82.53; envelope-from=mh.in.england@gmail.com;
	helo=mail-wg0-f53.google.com; 
MIME-Version: 1.0
Sender: mh.in.england@gmail.com
In-Reply-To: <54BD6314.60607@gmail.com>
References: <CAN5esQJe0uUm0NyctaBa6WH7_JjeE_OLR=FY_XQWnSr50VRDyA@mail.gmail.com>
	<CAJHLa0OTynX4oiQoyanpRKE2tpAuS4L5X-2j20328725J9RrvQ@mail.gmail.com>
	<2C7D6208-1921-4DDC-90FE-DB1ABE1D61DB@petertodd.org>
	<CAN5esQLCV=L0kYxDGhK2F=qZ8OqMxyYS+-Pn17U_M+nV4Sj3Og@mail.gmail.com>
	<54BD6314.60607@gmail.com>
Date: Mon, 19 Jan 2015 21:40:13 +0100
Message-ID: <CANEZrP3ZdFcQsP+EWgTYQDccFZbrZFTk+xi-YdWPCJzMRH79pA@mail.gmail.com>
From: Mike Hearn <mike@plan99.net>
To: Alan Reiner <etotheipi@gmail.com>
Content-Type: multipart/alternative; boundary=e89a8f3ba0854745fb050d075487
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] BIP70: why Google Protocol Buffers for
	encoding?
Precedence: list

--e89a8f3ba0854745fb050d075487
Content-Type: text/plain; charset=UTF-8

>
> I'm a bit confused.  It's been a long time since I looked at protobuf (and
> will have to dig into it soon), but I seem to recall it doesn't have any of
> the determinism properties you guys just said.
>

It's not guaranteed no, which is why we store signed sub-messages as byte
arrays instead of typed submessages. In practice though, most
implementations do seem to serialise things the same way. I recall Python
used to be an odd one out, unsure if it still is.

OK, I guess we can boil this down more simply. BIP 70 uses protocol buffers
because I designed it and implemented the original prototype (with lots of
input from Gavin and an earlier proposal by sipa). I used protocol buffers
because, beyond all their nice properties, I used to work at Google and so
was very familiar with them.

--e89a8f3ba0854745fb050d075487
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><blo=
ckquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #c=
cc solid;padding-left:1ex"><div bgcolor=3D"#FFFFFF" text=3D"#000000">I&#39;=
m a bit confused.=C2=A0 It&#39;s been a long time since I looked at
    protobuf (and will have to dig into it soon), but I seem to recall
    it doesn&#39;t have any of the determinism properties you guys just
    said.=C2=A0</div></blockquote><div><br></div><div>It&#39;s not guarante=
ed no, which is why we store signed sub-messages as byte arrays instead of =
typed submessages. In practice though, most implementations do seem to seri=
alise things the same way. I recall Python used to be an odd one out, unsur=
e if it still is.</div><div><br></div><div>OK, I guess we can boil this dow=
n more simply. BIP 70 uses protocol buffers because I designed it and imple=
mented the original prototype (with lots of input from Gavin and an earlier=
 proposal by sipa). I used protocol buffers because, beyond all their nice =
properties, I used to work at Google and so was very familiar with them.</d=
iv><div><br></div></div></div></div>

--e89a8f3ba0854745fb050d075487--