path: root/template/developers.html.j2

{% extends "common/base.j2" %}
{% block body_content %}
<div class="jumbotron">
  <div class="text-center">
    <h1>{{ _("Taler for developers") }}</h1>
  </div>
</div>

<div class="container">
  <div class="row">
    <div class="col-lg-6">
      <h3>{{ _("Free") }}</h3>

      <p>
        {% trans %}
          GNU Taler is free software implementing an open
          protocol. Anybody is welcome to 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 GPLv3+ are used for
          wallets and related customer-facing software.  We are
          open for constructive suggestions for maximizing the
          adoption of this payment platform.
         {% endtrans %}
      </p>

    </div>
    <div class="col-lg-6">
      <h3>{{ _("RESTful") }}</h3>

      <p>
        {% trans %}
          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 at
          <a href="https://docs.taler.net/">docs.taler.net</a>.
        {% endtrans %}
      </p>
    </div>
  </div>
</div>

<div class="container-fluid c_acronym">
<div class="container">
  <div class="row">
    <div class="col-lg-4">
      <h3>{{ _("Code") }}</h3>

      <p>
        {% trans %}
          Taler is currently primarily developed by a
          research team at <a href="http://www.inria.fr/">Inria</a> and
          <a href="https://gnunet.org/">GNUnet</a>. 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
          repositories can be found in our
          <a href="https://git.taler.net/">GitWeb</a>.
        {% endtrans %}
     </p>
    </div>
    <div class="col-lg-4">
      <h3>{{ _("Documentation") }}</h3>

      <p>
        {% trans %}
          In addition to this website, the
          <a href="https://git.taler.net/">documented code</a>
          and the
          <a href="https://docs.taler.net/">API documentation</a>.
          Technical papers can be found in our
          <a href="bibliography.html">bibliography</a>.
       {% endtrans %}
      </p>
    </div>
     <div class="col-lg-4">
      <h3>{{ _("Discussion") }}</h3>

      <p>
        {% trans %}
          We have a mailing list for developer discussions.
          You can subscribe to or read the list archive at
          <a href="http://lists.gnu.org/mailman/listinfo/taler">http://lists.gnu.org/mailman/listinfo/taler</a>.
        {% endtrans %}
      </p>
    </div>
  </div>
  <div class="row">
    <div class="col-lg-4">
      <h3>{{ _("Regression Testing") }}</h3>

      <p>
         {% trans %}
           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>.
        {% endtrans %}
       </p>
    </div>
    <div class="col-lg-4" note="not yet operational">
      <h3>{{ _("Code Coverage Analysis") }}</h3>

      <p>
         {% trans %}
           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>.
        {% endtrans %}
      </p>
    </div>
  </div>
</div>
</div>

<div class="container-fluid">
 <div class="container">
   <h2>{{ _("Technical Presentation") }}</h2>
  <div class="row">
   <div class="col-lg-4">
     <a href="{{ url('presentations/tech.pdf') }}"><img border=0 class="center-block" width=64 height=64 alt="PDF" src="{{ url('images/pdf.svg') }}"><br><p align="center">{{ _("Download") }}</p></a>
   </div>
   <div class="col-lg-4" id="canvas-left" style="display:none">
     <canvas id="the-canvas-left"></canvas>
   </div>
   <div class="col-lg-4" id="canvas-right" style="display:none">
    <canvas id="the-canvas-right"></canvas>
   </div>
   <script type="text/javascript" src="{{ url('dist/js/pdf.min.js') }}"></script>
   <script type="text/javascript" src="{{ url('dist/js/pdf-view-tech.js') }}"></script>
  </div>
 </div>
</div>

<div class="container">
  <div class="col-lg-12">
    <h3 id="overview">{{ _("Taler system overview") }}</h3>

    <p>
      {% trans %}
        The Taler system consists of protocols executed among
        a number of actors as illustrated in the illustration on the right.
        Typical transactions involve the following steps:
      {% endtrans %}
     </p>

      <img src="/images/taler-arch-full.svg" alt="{{_("system overview")}}" style="float: right; margin: 50px 5px 5px 5px;" width="50%">
      <ol>
         <li>
           {% trans %}
             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.
           {% endtrans %}
            </li>

         <li>
           {% trans %}
             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 &quot;serial
             numbers&quot; 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).
           {% endtrans %}
         </li>

         <li>
           {% trans %}
             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).
           {% endtrans %}
            </li>

         <li>
           {% trans %}
             Merchants receiving digital
             coins <b>deposit</b> the respective claims
             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).
           {% endtrans %}
         </li>

         <li>
           {% trans %}
             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.
           {% endtrans %}
         </li>

         <li>
           {% trans %}
             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.
           {% endtrans %}
         </li>

         <li>
           {% trans %}
             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.
           {% endtrans %}
         </li>
      </ol>
    <p></p>
    <div class="col">
      <img class="img-fluid" src="../images/diagram-complex.png">
    </div>
  </div>
</div> <!-- /container -->
{% endblock body_content %}