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DMBCS Kraken API
Copyright © 2018 DM Bespoke Computer Solutions Ltd
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.
A copy of the license is also available from the Free Software Foundation Web site at http://www.gnu.org/licenses/fdl.html.
| • Introduction: | ||
| • Installation of the library: | ||
| • Use example: | ||
| • Detailed reference: | ||
| • Copying This Manual: | ||
| • Function index: | ||
| • Index: |
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Kraken is a virtual currency exchange, which also handles fiat (real) currency amounts. Subscribers to the service have an account with associated funds attached. The web site (www.kraken.com) provides the user with an account overview (i.e. current balance), currency-pair exchange market status (history of prices and current order book), and the means to place entries on the order book; bids for a currency which can be immediately met with orders to sell the currency are automatically transacted, with the Kraken site taking a small and variable cut of the deal, the cut decreasing with intensifying trading activity.
Kraken also provide a stateless, web-based API by which all of the above actions can be undertaken programmatically. This is fully open, and described at www.kraken.com/help/api. The description is almost, but not quite, enough to fully specify the interaction protocol. Kraken also provide pointers to implementations of client-side API libraries in various languages, and reference to these must be made in order to fully understand the working of the Kraken API (the official reference implementation is written in PHP).
Kraken provide pointers to two proven client library implementations that we are immediately interested in: a C implementation and a C++ one. Unfortunately the C++ implementation only provides the thinnest veneer around TCP sockets, requiring the application programmer to have knowledge of the low-level protocol in order to be able to compose correct strings which implement the protocol, which defeats the purpose somewhat. The C library is more comprehensive, shadowing all the functions exposed by Krakenʼs API as C functions, although they return ASCII strings holding data in JSON format which needs further processing (we actually take this approach ourself; there are plenty of good JSON libraries available, and in many cases it will be most expedient to simply send the JSON strings to a web browser and let a Javascript program there perform the required onwards analysis).
The main purpose of the DMBCS implementation is to get the best of both worlds: to have the API-completeness of the C implementation and the resource-management and detail-hiding convenience and safety promised by the above C++ implementation, so that the user does not need to understand anything of the protocol themself1.
This isnʼt a vanity or promotional project with any kind of commercial restriction, it is something that was needed and is being shared so that others can benefit from the effort that has been spent on the development, and hopefully improve upon it.
It is apparent from the above that many libraries exist to interact with the Kraken facility, and we would not want to preclude the use of any of them by the installation and use of our own. We also need a way to refer to our own implementation specifically. So we use ‘DMBCS’ to provide our distinguishing label: this is appended to the front of the package name, and all of the C++ code comes inside a namespace with this label. These should be considered to be five random letters: okay, they are abbreviated from DM Bespoke Computer Solutions Ltd, the original authorʼs company, but the project is released as fully free, open source software (FOSS) which falls under the GNU GPLv3 license, so you should treat it as any other component in your free, open operating system (Please donʼt tell me you actually pay money for some inferior OS beyond the eyes of humble scrutineers).
Returns are JSON strings.
We could have developed the library to the extent that these are fully
broken out into structs, but we had no immediate need for this
and think that it is actually easier to just use rapidjson which
effectively provides the same thing without imposing processing overhead
when it is not needed; a future version of this library may come with
the requisite aparatus.
For now, either send the return strings to a web browser to be handled
directly by ECMAScript (JavaScript), or, if it is required to handle
them locally then we find that rapidjson
(https://github.com/Tencent/rapidjson) is recommendable, though
there are plenty of other open-source JSON parsers out there.
Next: Use example, Previous: Introduction, Up: Top [Contents][Index]
You will require the git code management system. At the
terminal, type git clone https://rdmp.org/dmbcs/kraken-api.git
dmbcs-kraken-api, and then you will have a newly created directory
called dmbcs-kraken-api which contains the full source code for
the program. Type cd dmbcs-kraken-api to enter that directory.
The libraryʼs build configuration system is GNUʼs autotools. You
will need autoconf, automake, and libtool, and
pkg-config. At the terminal, type autoreconf --install;
./configure.
You may at this point see errors relating to lack of openssl, curl,
curlpp packages. You must address these issues in your operating system
and perform a successful ./configure before you can proceed with
the dmbcs-kraken-api build.
The libraryʼs build is undertaken by GNU make. You will need the
make package on your system (GNU make is probably not necessary,
any modern incarnation of make will most likely suffice). Type
make && sudo make install to build and install the library in
your system. Note that the sudo command will require that you have
sufficient privilege on your system, and you may have to type in your
system password (for a local build not requiring such privilege, in a
pinch, do ./configure --prefix=install-here && make install).
That should be it. Try making and running the example program described below (Section 3).
Next: Detailed reference, Previous: Installation of the library, Up: Top [Contents][Index]
To get a summary of the current state of the market in Bitcoin—Dollar exchanges, write the following C++ code
#include <dmbcs-kraken-api.h>
#include <iostream>
int main ()
{
auto K = DMBCS::Kraken_API {"<your-key>", "<your-secret>"};
std::cout << K.ticker_info ("XXBTZUSD");
return 0;
}
Here, <your-key> and <your-secret> are strings which you
get from your Kraken account management page (do EVERYTHING in
your power to make sure nobody else sees these). Strictly speaking,
they are not necessary for the above example, but do allow you to make
calls on the K object which interrogate and manipulate your own
funds.
If this code is stored in a file called a.cc, compile it with a
line like (this should be typed all on one line, without the back-slash)
g++ -std=c++17 $( pkg-config --cflags --libs dmbcs-kraken-api) \ a.cc -o kraken-api
and then you will have an executable file called kraken-api. Run
this and observe the result in your terminal (you should see a string
containing JSON-formatted data).
If this doesnʼt work for you, you either havenʼt installed dmbcs-kraken-api properly yet (see instructions in Section 2 above), or you need to improve your operating system, or get a better one; this is as far as we hand-hold you here.
Next: Copying This Manual, Previous: Use example, Up: Top [Contents][Index]
An important point of note. Any code base which includes the
dmbcs-kraken-api.h header file anywhere will have the
libcurlpp library automatically initialized during start-up and
finalized on termination of the application. If you are using
libcurlpp for your own endeavours, you will have to take care to
ensure that start-up and shut-down happen in ways which are compatible
with your own code.
Note that the dmbcs-kraken-api library itself requires no
explicit global initialization or finalization.
The library is not thread safe; there are severe limits to the volume
and regularity of data transfer through the Kraken API, and, given the
turn-around times of the accesses, access to the library should be
considered a strictly serial activity for which parallelism has no
purpose. If, however, delayed blocking behaviour is unsatisfactory for
your application and you need to realize asynchronous communications
channels with the Exchange, running the dmbcs-kraken-api entirely
in a thread separate from the main one would be appropriate.
The library provides one single object called DMBCS::Kraken_API.
This has a single initializing constructor2, and then has one method for each function
Kraken expose in their API. Each of these functions returns the result
as a string conveying data in JSON format, which may include an error
code and message.
It would be folly to describe in detail the Kraken API itself here; we content ourselves with describing our functionsʼ detailed call signatures and trusting the user to be able to find detailed notes on Krakenʼs web site, https://www.kraken.com/help/api.
DMBCS::Kraken_API::Kraken_API (std::string const &key, std::string const &secret)
This is the only way to create an initial API-wrapping object. The
key and secret must be obtained from the account
management page at the Kraken web site (strictly speaking, they do not
need to be valid for general exchange-state inquiries, only for personal
account introspection and trading).
Example use:
auto K = DMBCS::Kraken_API {"my-key", "my-secret"};
provides an object K which is subsequently used to access the
Kraken exchange, as per the further examples below.
template <typename T> void DMBCS::Kraken_API::set_opt (Option const &opt, T const &val)
Many of the Kraken API functions allow for the specification of optional
filters to control the amount and nature of information returned. These
are specified in the DMBCS library through the set_opt template method.
The option selection is done through constants provided in
Kraken_API: choose one of
INFO, ACLASS, ASSET, TRADES, USERREF, START, END, OFS, CLOSE_TIME,
DO_CALCS, PAIR, FEE_INFO, OFLAGS, START_TIME, EXPIRE_TIME, VALIDATE,
LEVERAGE, TYPE, CLOSE_TYPE, CLOSE_PRICE_1, CLOSE_PRICE_2, INTERVAL,
SINCE, COUNT
It is up to your application to provide an appropriate value for each
option — this is one of the corners where the Kraken_API does not
completely encapsulate the underlying protocol.
If it is necessary to subsequently unset an option, then a method
void DMBCS::Kraken_API::clear_opt (Option const &opt)
is available.
See the description of the asset_info method in Section
See asset_info below for an example of how to use these functions.
As mentioned above, these functions donʼt strictly need the userʼs key and secret strings. They provide non-confidential information about the state of the whole exchange, rather than the state of a userʼs account with the exchange.
std::string DMBCS::Kraken_API::server_time ()
This will return the current time as understood by the Kraken service.
Example:
std::cout << K.server_time ();
prints something like
{"error":[],"result":{"unixtime":1525292746,"rfc1123":"Wed, 2 May 18
20:25:46 +0000"}}
on the terminal.
std::string DMBCS::Kraken_API::asset_info ()
This will return meta-information about a set of assets. The options
INFO, ACLASS and ASSET influence the return from
this function.
Example:
K.set_opt (K.ASSET, "XBTC"); std::cout << K.asset_info ();
will print something like
{"error":[],"result":{"XXBT":{"aclass":"currency","altname":"XBT","decima
ls":10,"display_decimals":5}}}
on the terminal. Note that it has corrected the spelling from “XBTC”!
std::string DMBCS::Kraken_API::asset_pairs ()
This function returns a list of pairs of asset types which may be traded for each other on the exchange, along with meta-data describing the exchange process.
The options INFO and PAIR will affect the value returned
from this function.
For example,
K.set_opt (K.PAIR, "XXBTZUSD"); std::cout << K.asset_pairs ();
will print something like
{"error":[],"result":{"XXBTZUSD":{"altname":"XBTUSD","aclass_base":"curre
ncy","base":"XXBT","aclass_quote":"currency","quote":"ZUSD","lot":"unit","pa
ir_decimals":1,"lot_decimals":8,"lot_multiplier":1,"leverage_buy":[2,3,4,5],
"leverage_sell":[2,3,4,5],"fees":[[0,0.26],[50000,0.24],[100000,0.22],[25000
0,0.2],[500000,0.18],[1000000,0.16],[2500000,0.14],[5000000,0.12],[10000000,
0.1]],"fees_maker":[[0,0.16],[50000,0.14],[100000,0.12],[250000,0.1],[500000
,0.08],[1000000,0.06],[2500000,0.04],[5000000,0.02],[10000000,0]],"fee_volum
e_currency":"ZUSD","margin_call":80,"margin_stop":40}}}
on the command line.
std::string DMBCS::Kraken_API::ticker_info (std::string const &pair)
Provide up to date information about the state of the market in a trading pair.
std::cout << K.ticker_info ("XXBTZUSD");
will produce something like
{"error":[],"result":{"XXBTZUSD":{"a":["7616.30000","1","1.000"],"b":["7
610.10000","3","3.000"],"c":["7616.30000","0.00840000"],"v":["941.52501200"
,"2032.58702329"],"p":["7638.63864","7661.37306"],"t":[3099,6798],"l":["759
6.00000","7596.00000"],"h":["7700.00000","7728.90000"],"o":"7679.40000"}}}
on the command line. Briefly, the components of the result are:
ask, bid, close, volume, weighted-volume, trades, low, high, and open,
wherein the interval-dependent quantities refer to the last 24 hours.
std::string DMBCS::Kraken_API::ohlc_data (std::string const &pair)
The abbreviation “ohlc” stands for “open, high, low, close,” and this function will return a history of these values for a given interval.
The pair argument should specify a trading pair, such as
"XXBTZUSD" for Bitcoin—Dollar trading.
The function is affected by the INTERVAL and SINCE
options.
std::string DMBCS::Kraken_API::order_book (std::string const &pair)
This function returns live details of current bidding and asking prices and the volumes being offered.
The pair argument should specify a trading pair code, such as
"XXBTZUSD".
The function is affected by the COUNT option.
std::string DMBCS::Kraken_API::recent_trades (std::string const &pair)
This function returns an up to date list of all recently concluded trades.
The pair argument should indicate a trading pair, such as
"XXBTZUSD".
The function is affected by the SINCE option.
std::string DMBCS::Kraken_API::spread_data (std::string const &pair)
This function returns a history of instantaneous highest bid and lowest offer values for this trading pair on the exchange.
The pair argument should indicate a trading pair, such as
"XXBTZUSD".
The function is affected by the SINCE option.
These functions are for inquiring into the current state of the userʼs account.
std::string account_balance ()
This function returns a list of currencies and the amount of each Kraken is holding for you on account.
std::string trade_balance ()
This function provides a snapshot of your current trading activities, expressing your current balance in terms of potential value in a given currency.
The currency may be set with the ASSET option. The ACLASS
option is also available, and may have some use in a future version of
Krakenʼs API.
std::string open_orders ()
This function provides a very detailed description of the current state of all of your open orders, including the amount of fulfilment that has been completed and the conduct of on-going actions, such as close-out.
The function is affected by the TRADES and USERREF options.
std::string closed_orders ()
Similarly to the open_orders function above, this function
provides detailed information of your closed orders. Note that a
maximum of 50 records will be returned by this function; use the
OFS option in repeat calls to get information on more items.
The options which affect this function are: TRADES,
USERREF, START, END, OFS and
CLOSETIME.
std::string query_orders (std::string const &txid)
As the above two functions, but returns data specifically about a given
set of orders, identified by their transaction ID. The txid
argument is a string containing a comma-separated list of transaction
IDs.
The function is affected by the TRADES and USERREF
options.
std::string trades_history ()
This returns very detailed information about your trading history. A
maximum of 50 records will be returned; use the OFS option in
repeat calls to get more information.
Other options which affect the outcome from this function are:
TYPE, TRADES, START, and END.
std::string trades_info (std::string const &txid)
Gets detailed information, as the method above, for a very specific set
of trades you have completed in the past. The txid argument is a
string containing a comma-separated list of transaction IDs.
This function is affected by the TRADES option, which causes more
information to be returned (the value given to the option is irrelevant).
std::string open_positions (std::string const &txid)
Get detailed information on specific open positions, optionally with
calculation of expected profit/loss given the current conditions of the
exchange. The txid argument is a string containing a
comma-separated list of transaction IDs.
This function is affected by the DOCALCS option (the actual value
of this option is irrelevant).
std::string ledgers_info ()
This is the method which allows you to get the definitive history (e.g.,
for tax purposes), of your activities on the Kraken exchange, including
exact fees which have been charged to your account. The method will
only return 50 items at a time, so you will likely need to make multiple
requests with different START, END and/or OFS
option settings to get the full record.
The list of options which affect this function are: ACLASS,
ASSET, TYPE, START, END and OFS.
std::string query_ledgers (std::string const &id)
As above, but return information about a specific set of ledger
entries. The id argument is a string containing a
comma-separated list of ledger item IDs.
std::string trade_volume ()
This function returns information about actual and potential costs of trading based on the userʼs recent trading volume.
The function is affected by the PAIR and FEE_INFO options.
The final two functions in the Kraken API are for actively submitting order instructions to the Kraken exchange. Use these with extreme care, especially during the development phase of your application; it is too easy to accidentally lose a lot of money!
std::string DMBCS::Kraken_API::add_order (Order_Instruction const &instruction, Order_Type const &order, std::string const &asset, std::string const &volume, ...)
This is the single method available for adding an instruction to the Kraken engine to execute a trade order on your behalf.
The available instructions are: DMBCS::Kraken_API::BUY and
DMBCS::Kraken_API::SELL.
The available order types, again in the DMBCS::Kraken_API
namespace but shown without for brevity, are: MARKET,
LIMIT, STOP_LOSS, TAKE_PROFIT,
STOP_LOSS_PROFIT, STOP_LOSS_PROFIT_LIMIT,
STOP_LOSS_LIMIT, TAKE_PROFIT_LIMIT, TRAILING_STOP,
TRAILING_STOP_LIMIT, STOP_LOSS_AND_LIMIT,
SETTLE_POSITION.
The asset argument must indicate the asset pair to trade. For
example, to buy Bitcoin for Dollars the asset should be
"XXBTZUSD".
The volume argument must be the amount of the asset you are
buying or selling.
If your order type is one of LIMIT, STOP_LOSS, TAKE_PROFIT, or TRAILING_STOP, then you must supply an extra argument which gives the price at which the action takes place. If your order type is one of STOP_LOSS_PROFIT, STOP_LOSS_PROFIT_LIMIT, STOP_LOSS_LIMIT, TAKE_PROFIT_LIMIT, TRAILING_STOP_LIMIT, STOP_LOSS_AND_LIMIT, then you must supply two extra arguments to the method: a price_1 and a price_2 which give the limits at which primary and secondary actions take place.
Note that all the ‘numerical’ arguments are in fact strings. These are sent to the Kraken exchange as-is, and thus must be in a form that can be parsed into bona-fide numbers. It is done this way to guarantee no loss of precision due to such things as numerical rounding or truncating a floating-point value to an integer.
Further to the somewhat complicated arrangement of compulsory arguments
given above, the method is influenced by the following options:
LEVERAGE, OFLAGS, START_TIME, EXPIRE_TIME,
USERREF, VALIDATE, CLOSE_TYPE,
CLOSE_PRICE_1, and CLOSE_PRICE_2.
Please be very careful when composing complicated esoteric options: the Kraken engine itself has been known to be somewhat fragile with its interpretation of various combinations of options. Donʼt make any assumptions, try things out in the Kraken web interface first, and guard against spending any amount of money which means anything to you until you are absolutely sure you understand everything.
std::string DMBCS::Kraken_API::cancel_order (std::string const &txid)
Cancel the order with the given transaction ID (txid). Of course
this only works on the part of an order which has not been fulfilled by
the time the instruction manages to reach, and is acted upon by, the
Kraken exchange engine.
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This is not 100% true: when specifying currency pairs the user has to produce the correct ASCII string, e.g. “ZUSDXXBT” for the US Dollar/Bitcoin order book. We have taken this decision because it would be cumbersome to encapsulate all the different currencies, which in any case tend to change from time to time, especially as new crypto-currencies become available.
Plus a natural move
constructor, and nothing else: as per the parallelization discussion
above, it makes no sense to be able to make copies of the
Kraken_API object as the whole protocol only allows one operation
at a time to be in progress.