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<!DOCTYPE html>
<html lang="{{ _('en') }}">
<head>
<meta charset="UTF-8"/>
<title>{{ _("GNU Taler") }} - {{ _("Developers") }}</title>
<meta name="description" content=""/>
{% include "common/header.j2.inc" %}
</head>
<body>
<div class="container">
{% include "common/navigation.j2.inc" %}
<!-- Jumbotron -->
<div class="jumbotron">
<h1>{{ _("Taler for developers") }}</h1>
</div>
<!-- Example row of columns -->
<div class="row">
<div class="col-lg-6">
<h2>{{ _("Free") }}</h2>
<p>{{ _("Taler is free software implementing an open
protocol. Anybody is welcome to inspect our code
and integrate our reference implementation into
their applications. Different components of Taler
are being made available under different
licenses. The Affero GPLv3+ is used for the
exchange, the LGPLv3+ is used for reference code
demonstrating integration with merchant platforms,
and licenses like Apache/Mozilla/GPLv3+ are used
for wallets and related customer-facing software.
We are open for constructive suggestions for
maximizing the adoption of this libre payment
platform. ") }}</p>
</div>
<div class="col-lg-6">
<h2>{{ _("RESTful") }}</h2>
<p>{{ _("Taler is designed to work on the Internet. To
ensure that Taler payments can work with
restrictive network setups, Taler uses a RESTful
protocol over HTTP or HTTPS. Taler's security does
not depend upon the use of HTTPS, but obviously
merchants may choose to offer HTTPS for consistency
and because it generally is better for privacy
compared to HTTP. Taler uses JSON to encode
structure data, making it easy to integrate Taler
with existing Web applications. Taler's protocol
is documented in
detail <a href='https://api.taler.net/'>here</a>.
") }}</p>
</div>
</div>
<div class="row">
<div class="col-lg-4">
<h2>{{ _("Code") }}</h2>
<p>{{ _("Taler is currently primarily developed by a
research team at Inria and GNUnet e.V. However,
contributions from anyone are welcome. Our Git
repositories can be cloned using the Git and HTTP
access methods against <tt>git.taler.net</tt> with
the name of the respective repository. A list of
public repositories can be found in
our <a href='https://git.taler.net/'>GitWeb</a>.
") }}</p>
</div>
<div class="col-lg-4">
<h2>{{ _("Documentation") }}</h2>
<p>{{ _("In addition to this website,
the <a href='https://git.taler.net/'>documented
code</a> and
the <a href='https://api.taler.net/'>API
documentation</a>, we are in the process of
preparing a comprehensive design document which
will be published here soon. ") }}</p>
</div>
<div class="col-lg-4">
<h2>{{ _("Discussion") }}</h2>
<p>{{ _("We have a mailinglist for developer discussions.
You can subscribe to it or read the list archive at
<a href='http://lists.gnu.org/mailman/listinfo/taler'>http://lists.gnu.org/mailman/listinfo/taler</a>.") }}</p>
</div>
</div>
<div class="row">
<div class="col-lg-4">
<h2>{{ _("Regression Testing") }}</h2>
<p>{{ _("We have
<a href='https://buildbot.net/'>Buildbot</a>
automation tests to detect regressions and check
for portability at
<a href='https://buildbot.taler.net/'>buildbot.taler.net</a>.
") }}</p>
</div>
<div class="col-lg-4" note="not yet operational">
<h2>{{ _("Code Coverage Analysis") }}</h2>
<p>{{ _("We use
<a href='http://ltp.sourceforge.net/coverage/lcov.php'>LCOV</a>
to analyze the code coverage of our tests, the
results are available
at <a href='https://lcov.taler.net/'>lcov.taler.net</a>.
") }}</p>
</div>
<div class="col-lg-4">
<h2>{{ _("Performance Analysis") }}</h2>
<p>{{ _("We
use <a href='https://gnunet.org/gauger'>Gauger</a>
for performance regression analysis of the exchange
backend
at <a href='https://gauger.taler.net/'>gauger.taler.net</a>.
") }}</p>
</div>
</div>
<div class="col-lg-12">
<h2 id="overview">{{ _("Taler system overview") }}</h2>
<p>{{ _("The Taler system consists of protocols executed among
a number of actors with the help
of <a href='https://www.fsf.org/'>Free Software</a>
as illustrated in the illustration on the right.
Typical transactions involve the following steps: ")
}}</p>
<img src="{{ url('images/system.svg') }}" alt="system overview" style="float: right; margin: 50px 5px 5px 5px;" width="50%">
<ol>
<li>{{ _("A customer instructs his <b>bank</b> to
transfer funds from his account to the Taler
exchange (top left). In the subject of the
transaction, he includes an authentication
token from his electronic <b>wallet</b>. In
Taler terminology, the customer creates a
reserve at the exchange. ") }}</li>
<li>{{ _("Once the exchange has received the wire
transfer, it allows the customer's electronic
wallet to <b>withdraw</b> electronic coins.
The electronic coins are digital
representations of the original currency from
the transfer. It is important to note that the
exchange does not learn the "serial
numbers" of the coins created in this
process, so it cannot tell later which customer
purchased what at which merchant. The use of
Taler does not change the currency or the total
value of the funds (except for fees which the
exchange may charge for the service). ")
}}</li>
<li>{{ _("Once the customer has the digital coins in his
wallet, the wallet can be used to <b>spend</b>
the coins with merchant portals that support
the Taler payment system and accept the
respective exchange as a business partner
(bottom arrow). This creates a digital contract
signed by the customer's coins and the
merchant. If necessary, the customer can later
use this digitally signed contract in a court
of law to prove the exact terms of the contract
and that he paid the respective amount. The
customer does not learn the banking details of
the merchant, and Taler does not require the
merchant to learn the identity of the
customer. Naturally, the customer can spend any
fraction of his digital coins (the system takes
care of customers getting change). ") }}</li>
<li>{{ _("Merchants receiving digital
coins <b>deposit</b> the respective receipts
that resulted from the contract signing with
the customer at the exchange to redeem the
coins. The deposit step does not reveal the
details of the contract between the customer
and the merchant or the identity of the
customer to the exchange in any way. However,
the exchange does learn the identity of the
merchant via the provided bank routing
information. The merchant can, for example
when compelled by the state for taxation,
provide information linking the individual
deposit to the respective contract signed by
the customer. Thus, the exchange's database
allows the state to enforce that merchants pay
applicable taxes (and do not engage in illegal
contracts). ") }}</li>
<li>{{ _("Finally, the exchange transfers funds
corresponding to the digital coins redeemed by
the merchants to the merchant's <b>bank</b>
account. The exchange may combine multiple
small transactions into one larger bank
transfer. The merchant can query the exchange
about the relationship between the bank
transfers and the individual claims that were
deposited. ") }}</li>
<li>{{ _("Most importantly, the exchange keeps
cryptographic proofs that allow it to
demonstrate that it is operating correctly to
third parties. The system requires an
external <b>auditor</b>, such as a
government-appointed financial regulatory body,
to frequently verify the exchange's databases
and check that its bank balance matches the
total value of the remaining coins in
circulation. ") }}</li>
<li>{{ _("Without the auditor, the exchange operators
could embezzle funds they are holding in
reserve. Customers and merchants cannot cheat
each other or the exchange. If any party's
computers are compromised, the financial damage
is limited to the respective party and
proportional to the funds they have in
circulation during the period of the
compromise. ") }}</li>
</ol>
<p></p>
</div>
{% include "common/footer.j2.inc" %}:w
</div> <!-- /container -->
</body>
</html>
|
