1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194]
helo=mx.sourceforge.net)
by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
(envelope-from <dario.teixeira@nleyten.com>) id 1YNi3U-0006f2-Dw
for bitcoin-development@lists.sourceforge.net;
Tue, 17 Feb 2015 13:19:12 +0000
X-ACL-Warn:
Received: from slow1-d.mail.gandi.net ([217.70.178.86])
by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76)
id 1YNi3S-0005TY-PJ for bitcoin-development@lists.sourceforge.net;
Tue, 17 Feb 2015 13:19:12 +0000
Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net
[217.70.183.197])
by slow1-d.mail.gandi.net (Postfix) with ESMTP id C12624961EC
for <bitcoin-development@lists.sourceforge.net>;
Tue, 17 Feb 2015 14:00:59 +0100 (CET)
Received: from mfilter30-d.gandi.net (mfilter30-d.gandi.net [217.70.178.161])
by relay5-d.mail.gandi.net (Postfix) with ESMTP id 263A841C0E7
for <bitcoin-development@lists.sourceforge.net>;
Tue, 17 Feb 2015 14:00:51 +0100 (CET)
X-Virus-Scanned: Debian amavisd-new at mfilter30-d.gandi.net
Received: from relay5-d.mail.gandi.net ([217.70.183.197])
by mfilter30-d.gandi.net (mfilter30-d.gandi.net [10.0.15.180])
(amavisd-new, port 10024) with ESMTP id 14dGA5Xvj+-t
for <bitcoin-development@lists.sourceforge.net>;
Tue, 17 Feb 2015 14:00:49 +0100 (CET)
X-Originating-IP: 10.58.1.142
Received: from webmail.gandi.net (unknown [10.58.1.142])
(Authenticated sender: dario.teixeira@nleyten.com)
by relay5-d.mail.gandi.net (Postfix) with ESMTPA id A279C41C104
for <bitcoin-development@lists.sourceforge.net>;
Tue, 17 Feb 2015 14:00:49 +0100 (CET)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8;
format=flowed
Content-Transfer-Encoding: 7bit
Date: Tue, 17 Feb 2015 13:00:49 +0000
From: Dario Teixeira <dario.teixeira@nleyten.com>
To: bitcoin-development@lists.sourceforge.net
Message-ID: <9ec9df3b0ecb854fa19bd9100ed87d85@nleyten.com>
X-Sender: dario.teixeira@nleyten.com
User-Agent: Roundcube Webmail/0.9.5
X-Spam-Score: 0.0 (/)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
See http://spamassassin.org/tag/ for more details.
X-Headers-End: 1YNi3S-0005TY-PJ
Subject: [Bitcoin-development] More precise type information in API reference
X-BeenThere: bitcoin-development@lists.sourceforge.net
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: <bitcoin-development.lists.sourceforge.net>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development>
List-Post: <mailto:bitcoin-development@lists.sourceforge.net>
List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe>
X-List-Received-Date: Tue, 17 Feb 2015 13:19:12 -0000
Dear Bitcoin devs,
I am the author of OCaml-bitcoin [1], a library offering an OCaml
interface
to the official Bitcoin client API. For those who may be unfamiliar
with it,
OCaml is one of those functional programming languages with a very rich
and
expressive type system [2]. Given its emphasis on safety, its
industrial
users are disproportionally found in the aerospace and financial
sectors.
Now, OCaml programmers care a lot about types, because experience has
taught them that deep down most programming errors are just type errors.
From this stems my request: please consider defining more precisely the
type
information associated with each API call in the JSON-RPC reference [3].
To give you a better idea of what I'm talking about, please take a look
at
the API offered by OCaml-bitcoin [4], and the associated type
definitions
[5] (note that these have not been updated for Bitcoin Core 0.10 yet).
I've created the type definitions from information gathered from the
Bitcoin
wiki and from looking at the Bitcoin Core source-code. I wouldn't be
surprised
if it contains errors, because neither the source-code nor the wiki is
very
precise about the actual types being used. As an example, consider type
hexspk_t ("hex representation of script public key"). Is this really
the
same type used in both signrawtransaction and createmultisig?
Improving this situation would pose a minimal burden on bitcoin devs:
all
that would be required is defining the precise set of types used in the
RPC
API, and annotating the RPC calls either in the source-code itself or in
the
API reference documentation. It would make writing bindings such as
mine
far easier and less error prone, and it would have the added advantage
of
better documenting the Bitcoin Core source-code itself.
Also, note that it is not necessary to extend this request to the deep
data structures returned by some API calls. Consider for instance the
gettransaction function of the OCaml-bitcoin API: it returns the raw
JSON
object without any attempt to process it. This is because that's a
fairly
niche facility, and the bindings would balloon in size if I were to
process
every single large return object. Instead, the bindings take the more
pragmatic stance of only processing the parameters and return results
where
a strong type discipline is imperative.
When I raised this issue on IRC a number of questions were posed.
What follows is my attempt to answer them:
Q: What does it matter, if JSON only has a tiny set of types?
A: JSON being the serialisation format is irrelevant. The client
bindings
know that even if a public ECDSA key is serialised as a string, it
does
not stop being a public ECDSA key, and should only be used where a
public
ECDSA key is expected.
Q: What does it matter if the types are not even distinguished in the
C++
source of Bitcoin Core?
A: That is unfortunate, because it opens the door to bugs caused by
type
errors. Moreover, even if the C++ source is "stringly-typed" and
does
not enforce a strong type discipline, that does not mean that the
types
are not there. Even if a public and private key are both
represented
as strings, can you use one where the other is expected? If not,
then
they actually have different types!
Q: Isn't this a maintenance nightmare, given the changes to Bitcoin
core?
A: Actually, the most burdensome part is what motivated this message:
keeping track of the types used. If the Bitcoin API reference were
more precise, keeping the bindings up-to-date would be trivial and
even mechanical, because the API is now fairly stable.
Thank you very much for your attention, and for all the work you guys
put
into Bitcoin development. It is much appreciated and not acknowledged
often enough!
Best regards,
Dario Teixeira
[1] https://github.com/darioteixeira/ocaml-bitcoin
[2] http://ocaml.org/learn/description.html
[3] https://bitcoin.org/en/developer-reference#bitcoin-core-apis
[4] http://ocaml-bitcoin.forge.ocamlcore.org/apidoc/Bitcoin.ENGINE.html
[5] http://ocaml-bitcoin.forge.ocamlcore.org/apidoc/Bitcoin.html
|
