mirror of
https://github.com/corda/corda.git
synced 2024-12-30 17:57:02 +00:00
451 lines
34 KiB
HTML
451 lines
34 KiB
HTML
|
|
|
|
<!DOCTYPE html>
|
|
<!--[if IE 8]><html class="no-js lt-ie9" lang="en" > <![endif]-->
|
|
<!--[if gt IE 8]><!--> <html class="no-js" lang="en" > <!--<![endif]-->
|
|
<head>
|
|
<meta charset="utf-8">
|
|
|
|
<meta name="viewport" content="width=device-width, initial-scale=1.0">
|
|
|
|
<title>Writing a contract using clauses — R3 Corda latest documentation</title>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<link rel="stylesheet" href="_static/css/custom.css" type="text/css" />
|
|
|
|
|
|
|
|
|
|
|
|
<link rel="top" title="R3 Corda latest documentation" href="index.html"/>
|
|
<link rel="next" title="Writing a contract test" href="tutorial-test-dsl.html"/>
|
|
<link rel="prev" title="Writing a contract" href="tutorial-contract.html"/>
|
|
|
|
|
|
<script src="_static/js/modernizr.min.js"></script>
|
|
|
|
</head>
|
|
|
|
<body class="wy-body-for-nav" role="document">
|
|
|
|
<div class="wy-grid-for-nav">
|
|
|
|
|
|
<nav data-toggle="wy-nav-shift" class="wy-nav-side">
|
|
<div class="wy-side-scroll">
|
|
<div class="wy-side-nav-search">
|
|
|
|
|
|
|
|
|
|
<a href="index.html" class="icon icon-home"> R3 Corda
|
|
|
|
|
|
|
|
</a>
|
|
|
|
|
|
|
|
|
|
<div class="version">
|
|
latest
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div role="search">
|
|
<form id="rtd-search-form" class="wy-form" action="search.html" method="get">
|
|
<input type="text" name="q" placeholder="Search docs" />
|
|
<input type="hidden" name="check_keywords" value="yes" />
|
|
<input type="hidden" name="area" value="default" />
|
|
</form>
|
|
</div>
|
|
|
|
|
|
<br>
|
|
<a href="api/index.html">API reference</a>
|
|
|
|
</div>
|
|
|
|
<div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="main navigation">
|
|
|
|
|
|
|
|
<p class="caption"><span class="caption-text">Getting started</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="inthebox.html">What’s included?</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="getting-set-up.html">Getting set up</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="running-the-demos.html">Running the demos</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">Key concepts</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="data-model.html">Data model</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="transaction-data-types.html">Data types</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="merkle-trees.html">Transaction Tear-offs</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="consensus.html">Consensus model</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">The Corda node</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="clientrpc.html">Client RPC</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="messaging.html">Networking and messaging</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="persistence.html">Persistence</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="node-administration.html">Node administration</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="corda-configuration-files.html">The Corda Configuration File</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="node-services.html">A Brief Introduction To The Node Services</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">CorDapps</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="creating-a-cordapp.html">Creating a Cordapp</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="creating-a-cordapp.html#gradle-plugins-for-cordapps">Gradle Plugins for Cordapps</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">Tutorials</span></p>
|
|
<ul class="current">
|
|
<li class="toctree-l1"><a class="reference internal" href="where-to-start.html">Where to start</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="tutorial-contract.html">Writing a contract</a></li>
|
|
<li class="toctree-l1 current"><a class="current reference internal" href="#">Writing a contract using clauses</a><ul>
|
|
<li class="toctree-l2"><a class="reference internal" href="#commercial-paper-class">Commercial paper class</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="#clauses">Clauses</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="#group-clause">Group Clause</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="#summary">Summary</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="#debugging">Debugging</a></li>
|
|
</ul>
|
|
</li>
|
|
<li class="toctree-l1"><a class="reference internal" href="tutorial-test-dsl.html">Writing a contract test</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="tutorial-clientrpc-api.html">Client RPC API Tutorial</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="flow-state-machines.html">Flow state machines</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="oracles.html">Writing oracle services</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="tutorial-attachments.html">Using attachments</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="event-scheduling.html">Event scheduling</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">Other</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="network-simulator.html">Network Simulator</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="node-explorer.html">Node Explorer</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="initial-margin-agreement.html">Initial Margin Agreements</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">Component library</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="contract-catalogue.html">Contract catalogue</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="contract-irs.html">Interest Rate Swaps</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">Appendix</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="loadtesting.html">Load testing</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="secure-coding-guidelines.html">Secure coding guidelines</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="release-process.html">Release process</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="release-process.html#steps-to-cut-a-release">Steps to cut a release</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="release-notes.html">Release notes</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="building-the-docs.html">Building the documentation</a></li>
|
|
</ul>
|
|
<p class="caption"><span class="caption-text">Glossary</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="glossary.html">Glossary</a></li>
|
|
</ul>
|
|
|
|
|
|
|
|
</div>
|
|
</div>
|
|
</nav>
|
|
|
|
<section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">
|
|
|
|
|
|
<nav class="wy-nav-top" role="navigation" aria-label="top navigation">
|
|
<i data-toggle="wy-nav-top" class="fa fa-bars"></i>
|
|
<a href="index.html">R3 Corda</a>
|
|
</nav>
|
|
|
|
|
|
|
|
<div class="wy-nav-content">
|
|
<div class="rst-content">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<div role="navigation" aria-label="breadcrumbs navigation">
|
|
<ul class="wy-breadcrumbs">
|
|
<li><a href="index.html">Docs</a> »</li>
|
|
|
|
<li>Writing a contract using clauses</li>
|
|
<li class="wy-breadcrumbs-aside">
|
|
|
|
|
|
<a href="_sources/tutorial-contract-clauses.txt" rel="nofollow"> View page source</a>
|
|
|
|
|
|
</li>
|
|
</ul>
|
|
<hr/>
|
|
</div>
|
|
<div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
|
|
<div itemprop="articleBody">
|
|
|
|
<script type="text/javascript" src="_static/jquery.js"></script>
|
|
<script type="text/javascript" src="_static/codesets.js"></script><div class="section" id="writing-a-contract-using-clauses">
|
|
<h1>Writing a contract using clauses<a class="headerlink" href="#writing-a-contract-using-clauses" title="Permalink to this headline">¶</a></h1>
|
|
<p>This tutorial will take you through restructuring the commercial paper contract to use clauses. You should have
|
|
already completed “<a class="reference internal" href="tutorial-contract.html"><span class="doc">Writing a contract</span></a>”.</p>
|
|
<p>Clauses are essentially micro-contracts which contain independent verification logic, and can be logically composed
|
|
together to form a contract. Clauses are designed to enable re-use of common logic, for example issuing state objects
|
|
is generally the same for all fungible contracts, so a common issuance clause can be inherited for each contract’s
|
|
issue clause. This cuts down on scope for error, and improves consistency of behaviour. By splitting verification logic
|
|
into smaller chunks, they can also be readily tested in isolation.</p>
|
|
<p>Clauses can be composed of subclauses, for example the <code class="docutils literal"><span class="pre">AllClause</span></code> or <code class="docutils literal"><span class="pre">AnyClause</span></code> clauses take list of clauses
|
|
that they delegate to. Clauses can also change the scope of states and commands being verified, for example grouping
|
|
together fungible state objects and running a clause against each distinct group.</p>
|
|
<p>The commercial paper contract has a <code class="docutils literal"><span class="pre">Group</span></code> outermost clause, which contains the <code class="docutils literal"><span class="pre">Issue</span></code>, <code class="docutils literal"><span class="pre">Move</span></code> and <code class="docutils literal"><span class="pre">Redeem</span></code>
|
|
clauses. The result is a contract that looks something like this:</p>
|
|
<blockquote>
|
|
<div><ol class="arabic">
|
|
<li><dl class="first docutils">
|
|
<dt>Group input and output states together, and then apply the following clauses on each group:</dt>
|
|
<dd><ol class="first last loweralpha simple">
|
|
<li>If an <code class="docutils literal"><span class="pre">Issue</span></code> command is present, run appropriate tests and end processing this group.</li>
|
|
<li>If a <code class="docutils literal"><span class="pre">Move</span></code> command is present, run appropriate tests and end processing this group.</li>
|
|
<li>If a <code class="docutils literal"><span class="pre">Redeem</span></code> command is present, run appropriate tests and end processing this group.</li>
|
|
</ol>
|
|
</dd>
|
|
</dl>
|
|
</li>
|
|
</ol>
|
|
</div></blockquote>
|
|
<div class="section" id="commercial-paper-class">
|
|
<h2>Commercial paper class<a class="headerlink" href="#commercial-paper-class" title="Permalink to this headline">¶</a></h2>
|
|
<p>To use the clause verification logic, the contract needs to call the <code class="docutils literal"><span class="pre">verifyClause</span></code> function, passing in the
|
|
transaction, a clause to verify, and a collection of commands the clauses are expected to handle all of. This list of
|
|
commands is important because <code class="docutils literal"><span class="pre">verifyClause</span></code> checks that none of the commands are left unprocessed at the end, and
|
|
raises an error if they are. The top level clause would normally be a composite clause (such as <code class="docutils literal"><span class="pre">AnyComposition</span></code>,
|
|
<code class="docutils literal"><span class="pre">AllComposition</span></code>, etc.) which contains further clauses. The following examples are trimmed to the modified class
|
|
definition and added elements, for brevity:</p>
|
|
<div class="codeset container">
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">CommercialPaper</span> <span class="p">:</span> <span class="n">Contract</span> <span class="p">{</span>
|
|
<span class="k">override</span> <span class="k">val</span> <span class="py">legalContractReference</span><span class="p">:</span> <span class="n">SecureHash</span> <span class="p">=</span> <span class="n">SecureHash</span><span class="p">.</span><span class="n">sha256</span><span class="p">(</span><span class="s">"https://en.wikipedia.org/wiki/Commercial_paper"</span><span class="p">)</span>
|
|
|
|
<span class="k">override</span> <span class="k">fun</span> <span class="nf">verify</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">)</span> <span class="p">=</span> <span class="n">verifyClause</span><span class="p">(</span><span class="n">tx</span><span class="p">,</span> <span class="n">Clauses</span><span class="p">.</span><span class="n">Group</span><span class="p">(),</span> <span class="n">tx</span><span class="p">.</span><span class="n">commands</span><span class="p">.</span><span class="n">select</span><span class="p"><</span><span class="n">Commands</span><span class="p">>())</span>
|
|
</pre></div>
|
|
</div>
|
|
<div class="highlight-java"><div class="highlight"><pre><span></span><span class="kd">public</span> <span class="kd">class</span> <span class="nc">CommercialPaper</span> <span class="kd">implements</span> <span class="n">Contract</span> <span class="o">{</span>
|
|
<span class="nd">@Override</span>
|
|
<span class="kd">public</span> <span class="n">SecureHash</span> <span class="nf">getLegalContractReference</span><span class="o">()</span> <span class="o">{</span>
|
|
<span class="k">return</span> <span class="n">SecureHash</span><span class="o">.</span><span class="na">Companion</span><span class="o">.</span><span class="na">sha256</span><span class="o">(</span><span class="s">"https://en.wikipedia.org/wiki/Commercial_paper"</span><span class="o">);</span>
|
|
<span class="o">}</span>
|
|
|
|
<span class="nd">@Override</span>
|
|
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">verify</span><span class="o">(</span><span class="nd">@NotNull</span> <span class="n">TransactionForContract</span> <span class="n">tx</span><span class="o">)</span> <span class="kd">throws</span> <span class="n">IllegalArgumentException</span> <span class="o">{</span>
|
|
<span class="n">ClauseVerifier</span><span class="o">.</span><span class="na">verifyClause</span><span class="o">(</span><span class="n">tx</span><span class="o">,</span> <span class="k">new</span> <span class="n">Clauses</span><span class="o">.</span><span class="na">Group</span><span class="o">(),</span> <span class="n">extractCommands</span><span class="o">(</span><span class="n">tx</span><span class="o">));</span>
|
|
<span class="o">}</span>
|
|
</pre></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="section" id="clauses">
|
|
<h2>Clauses<a class="headerlink" href="#clauses" title="Permalink to this headline">¶</a></h2>
|
|
<p>We’ll tackle the inner clauses that contain the bulk of the verification logic, first, and the clause which handles
|
|
grouping of input/output states later. The clauses must extend the <code class="docutils literal"><span class="pre">Clause</span></code> abstract class, which defines
|
|
the <code class="docutils literal"><span class="pre">verify</span></code> function, and the <code class="docutils literal"><span class="pre">requiredCommands</span></code> property used to determine the conditions under which a clause
|
|
is triggered. Composite clauses should extend the <code class="docutils literal"><span class="pre">CompositeClause</span></code> abstract class, which extends <code class="docutils literal"><span class="pre">Clause</span></code> to
|
|
add support for wrapping around multiple clauses.</p>
|
|
<p>The <code class="docutils literal"><span class="pre">verify</span></code> function defined in the <code class="docutils literal"><span class="pre">Clause</span></code> interface is similar to the conventional <code class="docutils literal"><span class="pre">Contract</span></code> verification
|
|
function, although it adds new parameters and returns the set of commands which it has processed. Normally this returned
|
|
set is identical to the <code class="docutils literal"><span class="pre">requiredCommands</span></code> used to trigger the clause, however in some cases the clause may process
|
|
further optional commands which it needs to report that it has handled.</p>
|
|
<p>The <code class="docutils literal"><span class="pre">Move</span></code> clause for the commercial paper contract is relatively simple, so we will start there:</p>
|
|
<div class="codeset container">
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Move</span><span class="p">:</span> <span class="n">Clause</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>>()</span> <span class="p">{</span>
|
|
<span class="k">override</span> <span class="k">val</span> <span class="py">requiredCommands</span><span class="p">:</span> <span class="n">Set</span><span class="p"><</span><span class="n">Class</span><span class="p"><</span><span class="k">out</span> <span class="n">CommandData</span><span class="p">>></span>
|
|
<span class="k">get</span><span class="p">()</span> <span class="p">=</span> <span class="n">setOf</span><span class="p">(</span><span class="n">Commands</span><span class="p">.</span><span class="n">Move</span><span class="o">::</span><span class="k">class</span><span class="p">.</span><span class="n">java</span><span class="p">)</span>
|
|
|
|
<span class="k">override</span> <span class="k">fun</span> <span class="nf">verify</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">,</span>
|
|
<span class="n">inputs</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">State</span><span class="p">>,</span>
|
|
<span class="n">outputs</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">State</span><span class="p">>,</span>
|
|
<span class="n">commands</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">AuthenticatedObject</span><span class="p"><</span><span class="n">Commands</span><span class="p">>>,</span>
|
|
<span class="n">groupingKey</span><span class="p">:</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>?):</span> <span class="n">Set</span><span class="p"><</span><span class="n">Commands</span><span class="p">></span> <span class="p">{</span>
|
|
<span class="k">val</span> <span class="py">command</span> <span class="p">=</span> <span class="n">commands</span><span class="p">.</span><span class="n">requireSingleCommand</span><span class="p"><</span><span class="n">Commands</span><span class="p">.</span><span class="n">Move</span><span class="p">>()</span>
|
|
<span class="k">val</span> <span class="py">input</span> <span class="p">=</span> <span class="n">inputs</span><span class="p">.</span><span class="n">single</span><span class="p">()</span>
|
|
<span class="n">requireThat</span> <span class="p">{</span>
|
|
<span class="s">"the transaction is signed by the owner of the CP"</span> <span class="k">by</span> <span class="p">(</span><span class="n">input</span><span class="p">.</span><span class="n">owner</span> <span class="k">in</span> <span class="n">command</span><span class="p">.</span><span class="n">signers</span><span class="p">)</span>
|
|
<span class="s">"the state is propagated"</span> <span class="k">by</span> <span class="p">(</span><span class="n">outputs</span><span class="p">.</span><span class="n">size</span> <span class="p">==</span> <span class="m">1</span><span class="p">)</span>
|
|
<span class="c1">// Don't need to check anything else, as if outputs.size == 1 then the output is equal to</span>
|
|
<span class="c1">// the input ignoring the owner field due to the grouping.</span>
|
|
<span class="p">}</span>
|
|
<span class="k">return</span> <span class="n">setOf</span><span class="p">(</span><span class="n">command</span><span class="p">.</span><span class="n">value</span><span class="p">)</span>
|
|
<span class="p">}</span>
|
|
<span class="p">}</span>
|
|
</pre></div>
|
|
</div>
|
|
<div class="highlight-java"><div class="highlight"><pre><span></span><span class="kd">class</span> <span class="nc">Move</span> <span class="kd">extends</span> <span class="n">Clause</span><span class="o"><</span><span class="n">State</span><span class="o">,</span> <span class="n">Commands</span><span class="o">,</span> <span class="n">State</span><span class="o">></span> <span class="o">{</span>
|
|
<span class="nd">@NotNull</span>
|
|
<span class="nd">@Override</span>
|
|
<span class="kd">public</span> <span class="n">Set</span><span class="o"><</span><span class="n">Class</span><span class="o"><?</span> <span class="kd">extends</span> <span class="n">CommandData</span><span class="o">>></span> <span class="nf">getRequiredCommands</span><span class="o">()</span> <span class="o">{</span>
|
|
<span class="k">return</span> <span class="n">Collections</span><span class="o">.</span><span class="na">singleton</span><span class="o">(</span><span class="n">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">.</span><span class="na">class</span><span class="o">);</span>
|
|
<span class="o">}</span>
|
|
|
|
<span class="nd">@NotNull</span>
|
|
<span class="nd">@Override</span>
|
|
<span class="kd">public</span> <span class="n">Set</span><span class="o"><</span><span class="n">Commands</span><span class="o">></span> <span class="nf">verify</span><span class="o">(</span><span class="nd">@NotNull</span> <span class="n">TransactionForContract</span> <span class="n">tx</span><span class="o">,</span>
|
|
<span class="nd">@NotNull</span> <span class="n">List</span><span class="o"><?</span> <span class="kd">extends</span> <span class="n">State</span><span class="o">></span> <span class="n">inputs</span><span class="o">,</span>
|
|
<span class="nd">@NotNull</span> <span class="n">List</span><span class="o"><?</span> <span class="kd">extends</span> <span class="n">State</span><span class="o">></span> <span class="n">outputs</span><span class="o">,</span>
|
|
<span class="nd">@NotNull</span> <span class="n">List</span><span class="o"><?</span> <span class="kd">extends</span> <span class="n">AuthenticatedObject</span><span class="o"><?</span> <span class="kd">extends</span> <span class="n">Commands</span><span class="o">>></span> <span class="n">commands</span><span class="o">,</span>
|
|
<span class="nd">@NotNull</span> <span class="n">State</span> <span class="n">groupingKey</span><span class="o">)</span> <span class="o">{</span>
|
|
<span class="n">AuthenticatedObject</span><span class="o"><</span><span class="n">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">></span> <span class="n">cmd</span> <span class="o">=</span> <span class="n">requireSingleCommand</span><span class="o">(</span><span class="n">tx</span><span class="o">.</span><span class="na">getCommands</span><span class="o">(),</span> <span class="n">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">.</span><span class="na">class</span><span class="o">);</span>
|
|
<span class="c1">// There should be only a single input due to aggregation above</span>
|
|
<span class="n">State</span> <span class="n">input</span> <span class="o">=</span> <span class="n">single</span><span class="o">(</span><span class="n">inputs</span><span class="o">);</span>
|
|
|
|
<span class="k">if</span> <span class="o">(!</span><span class="n">cmd</span><span class="o">.</span><span class="na">getSigners</span><span class="o">().</span><span class="na">contains</span><span class="o">(</span><span class="n">input</span><span class="o">.</span><span class="na">getOwner</span><span class="o">()))</span>
|
|
<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">"Failed requirement: the transaction is signed by the owner of the CP"</span><span class="o">);</span>
|
|
|
|
<span class="c1">// Check the output CP state is the same as the input state, ignoring the owner field.</span>
|
|
<span class="k">if</span> <span class="o">(</span><span class="n">outputs</span><span class="o">.</span><span class="na">size</span><span class="o">()</span> <span class="o">!=</span> <span class="mi">1</span><span class="o">)</span> <span class="o">{</span>
|
|
<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">"the state is propagated"</span><span class="o">);</span>
|
|
<span class="o">}</span>
|
|
<span class="c1">// Don't need to check anything else, as if outputs.size == 1 then the output is equal to</span>
|
|
<span class="c1">// the input ignoring the owner field due to the grouping.</span>
|
|
<span class="k">return</span> <span class="n">Collections</span><span class="o">.</span><span class="na">singleton</span><span class="o">(</span><span class="n">cmd</span><span class="o">.</span><span class="na">getValue</span><span class="o">());</span>
|
|
<span class="o">}</span>
|
|
<span class="o">}</span>
|
|
</pre></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="section" id="group-clause">
|
|
<h2>Group Clause<a class="headerlink" href="#group-clause" title="Permalink to this headline">¶</a></h2>
|
|
<p>We need to wrap the move clause (as well as the issue and redeem clauses - see the relevant contract code for their
|
|
full specifications) in an outer clause that understands how to group contract states and objects. For this we extend
|
|
the standard <code class="docutils literal"><span class="pre">GroupClauseVerifier</span></code> and specify how to group input/output states, as well as the top-level to run on
|
|
each group. As with the top level clause on a contract, this is normally a composite clause that delegates to subclauses.</p>
|
|
<div class="codeset container">
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Group</span> <span class="p">:</span> <span class="n">GroupClauseVerifier</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>>(</span>
|
|
<span class="n">AnyComposition</span><span class="p">(</span>
|
|
<span class="n">Redeem</span><span class="p">(),</span>
|
|
<span class="n">Move</span><span class="p">(),</span>
|
|
<span class="n">Issue</span><span class="p">()))</span> <span class="p">{</span>
|
|
<span class="k">override</span> <span class="k">fun</span> <span class="nf">groupStates</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">):</span> <span class="n">List</span><span class="p"><</span><span class="n">TransactionForContract</span><span class="p">.</span><span class="n">InOutGroup</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>>></span>
|
|
<span class="p">=</span> <span class="n">tx</span><span class="p">.</span><span class="n">groupStates</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>></span> <span class="p">{</span> <span class="n">it</span><span class="p">.</span><span class="n">token</span> <span class="p">}</span>
|
|
<span class="p">}</span>
|
|
</pre></div>
|
|
</div>
|
|
<div class="highlight-java"><div class="highlight"><pre><span></span><span class="kd">class</span> <span class="nc">Group</span> <span class="kd">extends</span> <span class="n">GroupClauseVerifier</span><span class="o"><</span><span class="n">State</span><span class="o">,</span> <span class="n">Commands</span><span class="o">,</span> <span class="n">State</span><span class="o">></span> <span class="o">{</span>
|
|
<span class="kd">public</span> <span class="nf">Group</span><span class="o">()</span> <span class="o">{</span>
|
|
<span class="kd">super</span><span class="o">(</span><span class="k">new</span> <span class="n">AnyComposition</span><span class="o"><>(</span>
|
|
<span class="k">new</span> <span class="n">Clauses</span><span class="o">.</span><span class="na">Redeem</span><span class="o">(),</span>
|
|
<span class="k">new</span> <span class="n">Clauses</span><span class="o">.</span><span class="na">Move</span><span class="o">(),</span>
|
|
<span class="k">new</span> <span class="n">Clauses</span><span class="o">.</span><span class="na">Issue</span><span class="o">()</span>
|
|
<span class="o">));</span>
|
|
<span class="o">}</span>
|
|
|
|
<span class="nd">@NotNull</span>
|
|
<span class="nd">@Override</span>
|
|
<span class="kd">public</span> <span class="n">List</span><span class="o"><</span><span class="n">InOutGroup</span><span class="o"><</span><span class="n">State</span><span class="o">,</span> <span class="n">State</span><span class="o">>></span> <span class="nf">groupStates</span><span class="o">(</span><span class="nd">@NotNull</span> <span class="n">TransactionForContract</span> <span class="n">tx</span><span class="o">)</span> <span class="o">{</span>
|
|
<span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">groupStates</span><span class="o">(</span><span class="n">State</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="n">State</span><span class="o">::</span><span class="n">withoutOwner</span><span class="o">);</span>
|
|
<span class="o">}</span>
|
|
<span class="o">}</span>
|
|
</pre></div>
|
|
</div>
|
|
</div>
|
|
<p>For the <code class="docutils literal"><span class="pre">CommercialPaper</span></code> contract, this is the top level clause for the contract, and is passed directly into
|
|
<code class="docutils literal"><span class="pre">verifyClause</span></code> (see the example code at the top of this tutorial).</p>
|
|
</div>
|
|
<div class="section" id="summary">
|
|
<h2>Summary<a class="headerlink" href="#summary" title="Permalink to this headline">¶</a></h2>
|
|
<p>In summary the top level contract <code class="docutils literal"><span class="pre">CommercialPaper</span></code> specifies a single grouping clause of type
|
|
<code class="docutils literal"><span class="pre">CommercialPaper.Clauses.Group</span></code> which in turn specifies <code class="docutils literal"><span class="pre">GroupClause</span></code> implementations for each type of command
|
|
(<code class="docutils literal"><span class="pre">Redeem</span></code>, <code class="docutils literal"><span class="pre">Move</span></code> and <code class="docutils literal"><span class="pre">Issue</span></code>). This reflects the flow of verification: In order to verify a <code class="docutils literal"><span class="pre">CommercialPaper</span></code>
|
|
we first group states, check which commands are specified, and run command-specific verification logic accordingly.</p>
|
|
</div>
|
|
<div class="section" id="debugging">
|
|
<h2>Debugging<a class="headerlink" href="#debugging" title="Permalink to this headline">¶</a></h2>
|
|
<p>Debugging clauses which have been composed together can be complicated due to the difficulty in knowing which clauses
|
|
have been matched, whether specific clauses failed to match or passed verification, etc. There is “trace” level
|
|
logging code in the clause verifier which evaluates which clauses will be matched and logs them, before actually
|
|
performing the validation. To enable this, ensure trace level logging is enabled on the <code class="docutils literal"><span class="pre">Clause</span></code> interface.</p>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
</div>
|
|
</div>
|
|
<footer>
|
|
|
|
<div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
|
|
|
|
<a href="tutorial-test-dsl.html" class="btn btn-neutral float-right" title="Writing a contract test" accesskey="n">Next <span class="fa fa-arrow-circle-right"></span></a>
|
|
|
|
|
|
<a href="tutorial-contract.html" class="btn btn-neutral" title="Writing a contract" accesskey="p"><span class="fa fa-arrow-circle-left"></span> Previous</a>
|
|
|
|
</div>
|
|
|
|
|
|
<hr/>
|
|
|
|
<div role="contentinfo">
|
|
<p>
|
|
© Copyright 2016, Distributed Ledger Group, LLC.
|
|
|
|
</p>
|
|
</div>
|
|
Built with <a href="http://sphinx-doc.org/">Sphinx</a> using a <a href="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <a href="https://readthedocs.org">Read the Docs</a>.
|
|
|
|
</footer>
|
|
|
|
</div>
|
|
</div>
|
|
|
|
</section>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
<script type="text/javascript">
|
|
var DOCUMENTATION_OPTIONS = {
|
|
URL_ROOT:'./',
|
|
VERSION:'latest',
|
|
COLLAPSE_INDEX:false,
|
|
FILE_SUFFIX:'.html',
|
|
HAS_SOURCE: true
|
|
};
|
|
</script>
|
|
<script type="text/javascript" src="_static/jquery.js"></script>
|
|
<script type="text/javascript" src="_static/underscore.js"></script>
|
|
<script type="text/javascript" src="_static/doctools.js"></script>
|
|
|
|
|
|
|
|
|
|
|
|
<script type="text/javascript" src="_static/js/theme.js"></script>
|
|
|
|
|
|
|
|
|
|
<script type="text/javascript">
|
|
jQuery(function () {
|
|
SphinxRtdTheme.StickyNav.enable();
|
|
});
|
|
</script>
|
|
|
|
|
|
</body>
|
|
</html> |