mirror of
https://github.com/corda/corda.git
synced 2024-12-28 00:38:55 +00:00
379 lines
20 KiB
HTML
379 lines
20 KiB
HTML
<!-- If you edit this, then please make the same changes to layout_for_doc_website.html, as that is used for the web
|
|
doc site generation which we put analytics tracking on to identify any potential problem pages -->
|
|
|
|
|
|
|
|
|
|
<!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>Event scheduling — 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="Network Simulator" href="network-simulator.html"/>
|
|
<link rel="prev" title="Using attachments" href="tutorial-attachments.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>
|
|
<br>
|
|
<a href="https://discourse.corda.net">Discourse Forums</a>
|
|
<br>
|
|
<a href="http://slack.corda.net">Slack</a>
|
|
<br>
|
|
|
|
</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="getting-set-up-fault-finding.html">Troubleshooting</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="running-the-demos.html">Running the demos</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="CLI-vs-IDE.html">CLI vs IDE</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>
|
|
<li class="toctree-l1"><a class="reference internal" href="clauses.html">Clauses</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">CorDapp basics</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="tutorial-cordapp.html">The CorDapp template</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-file.html">Node configuration</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="corda-plugins.html">The Corda plugin framework</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="node-services.html">Brief introduction to the node services</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="permissioning.html">Network permissioning</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="tutorial-contract.html">Writing a contract</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="tutorial-contract-clauses.html">Writing a contract using clauses</a></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-integration-testing.html">Integration testing</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="tutorial-building-transactions.html">Building transactions</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="flow-state-machines.html">Writing flows</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="flow-testing.html">Writing flow tests</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="running-a-notary.html">Running a notary service</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="using-a-notary.html">Using a notary service</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 current"><a class="current reference internal" href="#">Event scheduling</a><ul>
|
|
<li class="toctree-l2"><a class="reference internal" href="#introduction">Introduction</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="#how-to-implement-scheduled-events">How to implement scheduled events</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="#an-example">An example</a></li>
|
|
</ul>
|
|
</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>
|
|
</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="setting-up-a-corda-network.html">What is a corda network?</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-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>
|
|
<li class="toctree-l1"><a class="reference internal" href="publishing-corda.html">Publishing Corda</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="azure-vm.html">Working with the Corda Demo on Azure Marketplace</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>Event scheduling</li>
|
|
<li class="wy-breadcrumbs-aside">
|
|
|
|
|
|
<a href="_sources/event-scheduling.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="event-scheduling">
|
|
<h1>Event scheduling<a class="headerlink" href="#event-scheduling" title="Permalink to this headline">¶</a></h1>
|
|
<p>This article explains our approach to modelling time based events in code. It explains how a contract
|
|
state can expose an upcoming event and what action to take if the scheduled time for that event is reached.</p>
|
|
<div class="section" id="introduction">
|
|
<h2>Introduction<a class="headerlink" href="#introduction" title="Permalink to this headline">¶</a></h2>
|
|
<p>Many financial instruments have time sensitive components to them. For example, an Interest Rate Swap has a schedule
|
|
for when:</p>
|
|
<ul class="simple">
|
|
<li>Interest rate fixings should take place for floating legs, so that the interest rate used as the basis for payments
|
|
can be agreed.</li>
|
|
<li>Any payments between the parties are expected to take place.</li>
|
|
<li>Any payments between the parties become overdue.</li>
|
|
</ul>
|
|
<p>Each of these is dependent on the current state of the financial instrument. What payments and interest rate fixings
|
|
have already happened should already be recorded in the state, for example. This means that the <em>next</em> time sensitive
|
|
event is thus a property of the current contract state. By next, we mean earliest in chronological terms, that is still
|
|
due. If a contract state is consumed in the UTXO model, then what <em>was</em> the next event becomes irrelevant and obsolete
|
|
and the next time sensitive event is determined by any successor contract state.</p>
|
|
<p>Knowing when the next time sensitive event is due to occur is useful, but typically some <em>activity</em> is expected to take
|
|
place when this event occurs. We already have a model for business processes in the form of <a class="reference internal" href="flow-state-machines.html"><span class="doc">flows</span></a>,
|
|
so in the platform we have introduced the concept of <em>scheduled activities</em> that can invoke flow state machines
|
|
at a scheduled time. A contract state can optionally described the next scheduled activity for itself. If it omits
|
|
to do so, then nothing will be scheduled.</p>
|
|
</div>
|
|
<div class="section" id="how-to-implement-scheduled-events">
|
|
<h2>How to implement scheduled events<a class="headerlink" href="#how-to-implement-scheduled-events" title="Permalink to this headline">¶</a></h2>
|
|
<p>There are two main steps to implementing scheduled events:</p>
|
|
<ul class="simple">
|
|
<li>Have your <code class="docutils literal"><span class="pre">ContractState</span></code> implementation also implement <code class="docutils literal"><span class="pre">SchedulableState</span></code>. This requires a method named
|
|
<code class="docutils literal"><span class="pre">nextScheduledActivity</span></code> to be implemented which returns an optional <code class="docutils literal"><span class="pre">ScheduledActivity</span></code> instance.
|
|
<code class="docutils literal"><span class="pre">ScheduledActivity</span></code> captures what <code class="docutils literal"><span class="pre">FlowLogic</span></code> instance each node will run, to perform the activity, and when it
|
|
will run is described by a <code class="docutils literal"><span class="pre">java.time.Instant</span></code>. Once your state implements this interface and is tracked by the
|
|
wallet, it can expect to be queried for the next activity when committed to the wallet.</li>
|
|
<li>If nothing suitable exists, implement a <code class="docutils literal"><span class="pre">FlowLogic</span></code> to be executed by each node as the activity itself.
|
|
The important thing to remember is that in the current implementation, each node that is party to the transaction
|
|
will execute the same <code class="docutils literal"><span class="pre">FlowLogic</span></code>, so it needs to establish roles in the business process based on the contract
|
|
state and the node it is running on. Each side will follow different but complementary paths through the business logic.</li>
|
|
</ul>
|
|
<div class="admonition note">
|
|
<p class="first admonition-title">Note</p>
|
|
<p class="last">The scheduler’s clock always operates in the UTC time zone for uniformity, so any time zone logic must be
|
|
performed by the contract, using <code class="docutils literal"><span class="pre">ZonedDateTime</span></code>.</p>
|
|
</div>
|
|
<p>In the short term, until we have automatic flow session set up, you will also likely need to install a network
|
|
handler to help with obtaining a unique and secure random session. An example is described below.</p>
|
|
<p>The production and consumption of <code class="docutils literal"><span class="pre">ContractStates</span></code> is observed by the scheduler and the activities associated with
|
|
any consumed states are unscheduled. Any newly produced states are then queried via the <code class="docutils literal"><span class="pre">nextScheduledActivity</span></code>
|
|
method and if they do not return <code class="docutils literal"><span class="pre">null</span></code> then that activity is scheduled based on the content of the
|
|
<code class="docutils literal"><span class="pre">ScheduledActivity</span></code> object returned. Be aware that this <em>only</em> happens if the wallet considers the state
|
|
“relevant”, for instance, because the owner of the node also owns that state. States that your node happens to
|
|
encounter but which aren’t related to yourself will not have any activities scheduled.</p>
|
|
</div>
|
|
<div class="section" id="an-example">
|
|
<h2>An example<a class="headerlink" href="#an-example" title="Permalink to this headline">¶</a></h2>
|
|
<p>Let’s take an example of the interest rate swap fixings for our scheduled events. The first task is to implement the
|
|
<code class="docutils literal"><span class="pre">nextScheduledActivity</span></code> method on the <code class="docutils literal"><span class="pre">State</span></code>.</p>
|
|
<div class="codeset container">
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span>override fun nextScheduledActivity(thisStateRef: StateRef,
|
|
flowLogicRefFactory: FlowLogicRefFactory): ScheduledActivity? {
|
|
val nextFixingOf = nextFixingOf() ?: return null
|
|
|
|
val (instant, duration) = suggestInterestRateAnnouncementTimeWindow(index = nextFixingOf.name,
|
|
source = floatingLeg.indexSource,
|
|
date = nextFixingOf.forDay)
|
|
return ScheduledActivity(flowLogicRefFactory.create(TwoPartyDealFlow.FixingRoleDecider::class.java,
|
|
thisStateRef, duration), instant)
|
|
}
|
|
</pre></div>
|
|
</div>
|
|
</div>
|
|
<p>The first thing this does is establish if there are any remaining fixings. If there are none, then it returns <code class="docutils literal"><span class="pre">null</span></code>
|
|
to indicate that there is no activity to schedule. Otherwise it calculates the <code class="docutils literal"><span class="pre">Instant</span></code> at which the interest rate
|
|
should become available and schedules an activity at that time to work out what roles each node will take in the fixing
|
|
business process and to take on those roles. That <code class="docutils literal"><span class="pre">FlowLogic</span></code> will be handed the <code class="docutils literal"><span class="pre">StateRef</span></code> for the interest
|
|
rate swap <code class="docutils literal"><span class="pre">State</span></code> in question, as well as a tolerance <code class="docutils literal"><span class="pre">Duration</span></code> of how long to wait after the activity is triggered
|
|
for the interest rate before indicating an error.</p>
|
|
<div class="admonition note">
|
|
<p class="first admonition-title">Note</p>
|
|
<p class="last">This is a way to create a reference to the FlowLogic class and its constructor parameters to
|
|
instantiate. The reference can be checked against a per-node whitelist of approved and allowable types as
|
|
part of our overall security sandboxing.</p>
|
|
</div>
|
|
<p>As previously mentioned, we currently need a small network handler to assist with session setup until the work to
|
|
automate that is complete. See the interest rate swap specific implementation <code class="docutils literal"><span class="pre">FixingSessionInitiationHandler</span></code> which
|
|
is responsible for starting a <code class="docutils literal"><span class="pre">FlowLogic</span></code> to perform one role in the fixing flow with the <code class="docutils literal"><span class="pre">sessionID</span></code> sent
|
|
by the <code class="docutils literal"><span class="pre">FixingRoleDecider</span></code> on the other node which then launches the other role in the fixing flow. Currently
|
|
the handler needs to be manually installed in the node.</p>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
</div>
|
|
</div>
|
|
<footer>
|
|
|
|
<div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
|
|
|
|
<a href="network-simulator.html" class="btn btn-neutral float-right" title="Network Simulator" accesskey="n">Next <span class="fa fa-arrow-circle-right"></span></a>
|
|
|
|
|
|
<a href="tutorial-attachments.html" class="btn btn-neutral" title="Using attachments" accesskey="p"><span class="fa fa-arrow-circle-left"></span> Previous</a>
|
|
|
|
</div>
|
|
|
|
|
|
<hr/>
|
|
|
|
<div role="contentinfo">
|
|
<p>
|
|
© Copyright 2016, R3 Limited.
|
|
|
|
</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> |