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Rebuilds docs.
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Joel Dudley
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Chris Rankin
Chris Rankin
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commit
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76
docs/build/html/oracles.html
vendored
76
docs/build/html/oracles.html
vendored
@ -34,6 +34,9 @@
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<link rel="index" title="Index"
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href="genindex.html"/>
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<link rel="search" title="Search" href="search.html"/>
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<link rel="top" title="R3 Corda latest documentation" href="index.html"/>
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<link rel="next" title="Using attachments" href="tutorial-attachments.html"/>
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<link rel="prev" title="Using a notary service" href="using-a-notary.html"/>
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@ -117,7 +120,7 @@ API reference: <a href="api/kotlin/corda/index.html">Kotlin</a>/ <a href="api/ja
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<p class="caption"><span class="caption-text">CorDapps</span></p>
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<ul>
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<li class="toctree-l1"><a class="reference internal" href="creating-a-cordapp.html">CorDapp basics</a></li>
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<li class="toctree-l1"><a class="reference internal" href="tutorial-cordapp.html">The CorDapp template</a></li>
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<li class="toctree-l1"><a class="reference internal" href="tutorial-cordapp.html">The example CorDapp</a></li>
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</ul>
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<p class="caption"><span class="caption-text">The Corda node</span></p>
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<ul>
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@ -389,31 +392,27 @@ parameter and <code class="docutils literal"><span class="pre">CommandData</span
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<span class="k">if</span> <span class="p">(!</span><span class="n">ftx</span><span class="p">.</span><span class="n">verify</span><span class="p">(</span><span class="n">merkleRoot</span><span class="p">))</span> <span class="p">{</span>
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<span class="k">throw</span> <span class="n">MerkleTreeException</span><span class="p">(</span><span class="s">"Rate Fix Oracle: Couldn't verify partial Merkle tree."</span><span class="p">)</span>
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<span class="p">}</span>
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<span class="c1">// Reject if we have something different than only commands.</span>
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<span class="k">val</span> <span class="py">leaves</span> <span class="p">=</span> <span class="n">ftx</span><span class="p">.</span><span class="n">filteredLeaves</span>
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<span class="n">require</span><span class="p">(</span><span class="n">leaves</span><span class="p">.</span><span class="n">inputs</span><span class="p">.</span><span class="n">isEmpty</span><span class="p">()</span> <span class="p">&&</span> <span class="n">leaves</span><span class="p">.</span><span class="n">outputs</span><span class="p">.</span><span class="n">isEmpty</span><span class="p">()</span> <span class="p">&&</span> <span class="n">leaves</span><span class="p">.</span><span class="n">attachments</span><span class="p">.</span><span class="n">isEmpty</span><span class="p">())</span>
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<span class="k">val</span> <span class="py">fixes</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">Fix</span><span class="p">></span> <span class="p">=</span> <span class="n">ftx</span><span class="p">.</span><span class="n">filteredLeaves</span><span class="p">.</span><span class="n">commands</span><span class="p">.</span>
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<span class="n">filter</span> <span class="p">{</span> <span class="n">identity</span><span class="p">.</span><span class="n">owningKey</span> <span class="k">in</span> <span class="n">it</span><span class="p">.</span><span class="n">signers</span> <span class="p">&&</span> <span class="n">it</span><span class="p">.</span><span class="n">value</span> <span class="k">is</span> <span class="n">Fix</span> <span class="p">}.</span>
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<span class="n">map</span> <span class="p">{</span> <span class="n">it</span><span class="p">.</span><span class="n">value</span> <span class="k">as</span> <span class="n">Fix</span> <span class="p">}</span>
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<span class="c1">// Reject signing attempt if we received more commands than we should.</span>
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<span class="k">if</span> <span class="p">(</span><span class="n">fixes</span><span class="p">.</span><span class="n">size</span> <span class="p">!=</span> <span class="n">ftx</span><span class="p">.</span><span class="n">filteredLeaves</span><span class="p">.</span><span class="n">commands</span><span class="p">.</span><span class="n">size</span><span class="p">)</span>
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<span class="k">throw</span> <span class="n">IllegalArgumentException</span><span class="p">()</span>
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<span class="c1">// Reject this signing attempt if there are no commands of the right kind.</span>
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<span class="k">if</span> <span class="p">(</span><span class="n">fixes</span><span class="p">.</span><span class="n">isEmpty</span><span class="p">())</span>
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<span class="k">throw</span> <span class="n">IllegalArgumentException</span><span class="p">()</span>
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<span class="c1">// For each fix, verify that the data is correct.</span>
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<span class="k">val</span> <span class="py">knownFixes</span> <span class="p">=</span> <span class="n">knownFixes</span> <span class="c1">// Snapshot</span>
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<span class="k">for</span> <span class="p">(</span><span class="n">fix</span> <span class="k">in</span> <span class="n">fixes</span><span class="p">)</span> <span class="p">{</span>
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<span class="c1">// Performing validation of obtained FilteredLeaves.</span>
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<span class="k">fun</span> <span class="nf">commandValidator</span><span class="p">(</span><span class="n">elem</span><span class="p">:</span> <span class="n">Command</span><span class="p">):</span> <span class="n">Boolean</span> <span class="p">{</span>
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<span class="k">if</span> <span class="p">(!(</span><span class="n">identity</span><span class="p">.</span><span class="n">owningKey</span> <span class="k">in</span> <span class="n">elem</span><span class="p">.</span><span class="n">signers</span> <span class="p">&&</span> <span class="n">elem</span><span class="p">.</span><span class="n">value</span> <span class="k">is</span> <span class="n">Fix</span><span class="p">))</span>
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<span class="k">throw</span> <span class="n">IllegalArgumentException</span><span class="p">(</span><span class="s">"Oracle received unknown command (not in signers or not Fix)."</span><span class="p">)</span>
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<span class="k">val</span> <span class="py">fix</span> <span class="p">=</span> <span class="n">elem</span><span class="p">.</span><span class="n">value</span> <span class="k">as</span> <span class="n">Fix</span>
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<span class="k">val</span> <span class="py">known</span> <span class="p">=</span> <span class="n">knownFixes</span><span class="p">[</span><span class="n">fix</span><span class="p">.</span><span class="n">of</span><span class="p">]</span>
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<span class="k">if</span> <span class="p">(</span><span class="n">known</span> <span class="p">==</span> <span class="k">null</span> <span class="p">||</span> <span class="n">known</span> <span class="p">!=</span> <span class="n">fix</span><span class="p">)</span>
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<span class="k">throw</span> <span class="n">UnknownFix</span><span class="p">(</span><span class="n">fix</span><span class="p">.</span><span class="n">of</span><span class="p">)</span>
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<span class="k">return</span> <span class="k">true</span>
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<span class="p">}</span>
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<span class="k">fun</span> <span class="nf">check</span><span class="p">(</span><span class="n">elem</span><span class="p">:</span> <span class="n">Any</span><span class="p">):</span> <span class="n">Boolean</span> <span class="p">{</span>
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<span class="k">return</span> <span class="k">when</span> <span class="p">(</span><span class="n">elem</span><span class="p">)</span> <span class="p">{</span>
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<span class="k">is</span> <span class="n">Command</span> <span class="p">-></span> <span class="n">commandValidator</span><span class="p">(</span><span class="n">elem</span><span class="p">)</span>
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<span class="k">else</span> <span class="p">-></span> <span class="k">throw</span> <span class="n">IllegalArgumentException</span><span class="p">(</span><span class="s">"Oracle received data of different type than expected."</span><span class="p">)</span>
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<span class="p">}</span>
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<span class="p">}</span>
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<span class="k">val</span> <span class="py">leaves</span> <span class="p">=</span> <span class="n">ftx</span><span class="p">.</span><span class="n">filteredLeaves</span>
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<span class="k">if</span> <span class="p">(!</span><span class="n">leaves</span><span class="p">.</span><span class="n">checkWithFun</span><span class="p">(</span><span class="o">::</span><span class="n">check</span><span class="p">))</span>
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<span class="k">throw</span> <span class="n">IllegalArgumentException</span><span class="p">()</span>
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<span class="c1">// It all checks out, so we can return a signature.</span>
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<span class="c1">//</span>
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<span class="c1">// Note that we will happily sign an invalid transaction, as we are only being presented with a filtered</span>
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@ -528,13 +527,12 @@ those for <code class="docutils literal"><span class="pre">NodeInterestRates.Ora
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<span class="p">}</span>
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<span class="p">}</span>
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<span class="k">class</span> <span class="nc">FixSignFlow</span><span class="p">(</span><span class="k">val</span> <span class="py">tx</span><span class="p">:</span> <span class="n">TransactionBuilder</span><span class="p">,</span> <span class="k">val</span> <span class="py">oracle</span><span class="p">:</span> <span class="n">Party</span><span class="p">,</span> <span class="k">val</span> <span class="py">filterFuns</span><span class="p">:</span> <span class="n">FilterFuns</span><span class="p">)</span> <span class="p">:</span> <span class="n">FlowLogic</span><span class="p"><</span><span class="n">DigitalSignature</span><span class="p">.</span><span class="n">LegallyIdentifiable</span><span class="p">>()</span> <span class="p">{</span>
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<span class="k">class</span> <span class="nc">FixSignFlow</span><span class="p">(</span><span class="k">val</span> <span class="py">tx</span><span class="p">:</span> <span class="n">TransactionBuilder</span><span class="p">,</span> <span class="k">val</span> <span class="py">oracle</span><span class="p">:</span> <span class="n">Party</span><span class="p">,</span>
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<span class="k">val</span> <span class="py">partialMerkleTx</span><span class="p">:</span> <span class="n">FilteredTransaction</span><span class="p">)</span> <span class="p">:</span> <span class="n">FlowLogic</span><span class="p"><</span><span class="n">DigitalSignature</span><span class="p">.</span><span class="n">LegallyIdentifiable</span><span class="p">>()</span> <span class="p">{</span>
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<span class="n">@Suspendable</span>
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<span class="k">override</span> <span class="k">fun</span> <span class="nf">call</span><span class="p">():</span> <span class="n">DigitalSignature</span><span class="p">.</span><span class="n">LegallyIdentifiable</span> <span class="p">{</span>
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<span class="k">val</span> <span class="py">wtx</span> <span class="p">=</span> <span class="n">tx</span><span class="p">.</span><span class="n">toWireTransaction</span><span class="p">()</span>
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<span class="k">val</span> <span class="py">partialMerkleTx</span> <span class="p">=</span> <span class="n">FilteredTransaction</span><span class="p">.</span><span class="n">buildMerkleTransaction</span><span class="p">(</span><span class="n">wtx</span><span class="p">,</span> <span class="n">filterFuns</span><span class="p">)</span>
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<span class="k">val</span> <span class="py">rootHash</span> <span class="p">=</span> <span class="n">wtx</span><span class="p">.</span><span class="n">id</span>
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<span class="k">val</span> <span class="py">resp</span> <span class="p">=</span> <span class="n">sendAndReceive</span><span class="p"><</span><span class="n">DigitalSignature</span><span class="p">.</span><span class="n">LegallyIdentifiable</span><span class="p">>(</span><span class="n">oracle</span><span class="p">,</span> <span class="n">SignRequest</span><span class="p">(</span><span class="n">rootHash</span><span class="p">,</span> <span class="n">partialMerkleTx</span><span class="p">))</span>
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<span class="k">return</span> <span class="n">resp</span><span class="p">.</span><span class="n">unwrap</span> <span class="p">{</span> <span class="n">sig</span> <span class="p">-></span>
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<span class="n">check</span><span class="p">(</span><span class="n">sig</span><span class="p">.</span><span class="n">signer</span> <span class="p">==</span> <span class="n">oracle</span><span class="p">)</span>
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@ -545,12 +543,13 @@ those for <code class="docutils literal"><span class="pre">NodeInterestRates.Ora
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<span class="p">}</span>
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</pre></div>
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</div>
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<p>You’ll note that the <code class="docutils literal"><span class="pre">FixSignFlow</span></code> requires a <code class="docutils literal"><span class="pre">FilterFuns</span></code> instance with the appropriate filter to include only
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the <code class="docutils literal"><span class="pre">Fix</span></code> commands. You can find a further explanation of this in <a class="reference internal" href="merkle-trees.html"><span class="doc">Transaction tear-offs</span></a>.</p>
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<p>You’ll note that the <code class="docutils literal"><span class="pre">FixSignFlow</span></code> requires a <code class="docutils literal"><span class="pre">FilterTransaction</span></code> instance which includes only <code class="docutils literal"><span class="pre">Fix</span></code> commands.
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You can find a further explanation of this in <a class="reference internal" href="merkle-trees.html"><span class="doc">Transaction tear-offs</span></a>. Below you will see how to build such transaction with
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hidden fields.</p>
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</div>
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</div>
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<div class="section" id="using-an-oracle">
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<h2>Using an oracle<a class="headerlink" href="#using-an-oracle" title="Permalink to this headline">¶</a></h2>
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<span id="filtering-ref"></span><h2>Using an oracle<a class="headerlink" href="#using-an-oracle" title="Permalink to this headline">¶</a></h2>
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<p>The oracle is invoked through sub-flows to query for values, add them to the transaction as commands and then get
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the transaction signed by the oracle. Following on from the above examples, this is all encapsulated in a sub-flow
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called <code class="docutils literal"><span class="pre">RatesFixFlow</span></code>. Here’s the <code class="docutils literal"><span class="pre">call</span></code> method of that flow.</p>
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@ -563,7 +562,8 @@ called <code class="docutils literal"><span class="pre">RatesFixFlow</span></cod
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<span class="n">tx</span><span class="p">.</span><span class="n">addCommand</span><span class="p">(</span><span class="n">fix</span><span class="p">,</span> <span class="n">oracle</span><span class="p">.</span><span class="n">owningKey</span><span class="p">)</span>
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<span class="n">beforeSigning</span><span class="p">(</span><span class="n">fix</span><span class="p">)</span>
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<span class="n">progressTracker</span><span class="p">.</span><span class="n">currentStep</span> <span class="p">=</span> <span class="n">SIGNING</span>
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<span class="k">val</span> <span class="py">signature</span> <span class="p">=</span> <span class="n">subFlow</span><span class="p">(</span><span class="n">FixSignFlow</span><span class="p">(</span><span class="n">tx</span><span class="p">,</span> <span class="n">oracle</span><span class="p">,</span> <span class="n">filterFuns</span><span class="p">))</span>
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<span class="k">val</span> <span class="py">mtx</span> <span class="p">=</span> <span class="n">tx</span><span class="p">.</span><span class="n">toWireTransaction</span><span class="p">().</span><span class="n">buildFilteredTransaction</span><span class="p">({</span> <span class="n">filtering</span><span class="p">(</span><span class="n">it</span><span class="p">)</span> <span class="p">})</span>
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<span class="k">val</span> <span class="py">signature</span> <span class="p">=</span> <span class="n">subFlow</span><span class="p">(</span><span class="n">FixSignFlow</span><span class="p">(</span><span class="n">tx</span><span class="p">,</span> <span class="n">oracle</span><span class="p">,</span> <span class="n">mtx</span><span class="p">))</span>
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<span class="n">tx</span><span class="p">.</span><span class="n">addSignatureUnchecked</span><span class="p">(</span><span class="n">signature</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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@ -574,14 +574,12 @@ called <code class="docutils literal"><span class="pre">RatesFixFlow</span></cod
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<li>Does some quick validation.</li>
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<li>Adds the command to the transaction containing the fact to be signed for by the oracle.</li>
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<li>Calls an extension point that allows clients to generate output states based on the fact from the oracle.</li>
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<li>Builds filtered transaction based on filtering function extended from <code class="docutils literal"><span class="pre">RatesFixFlow</span></code>.</li>
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<li>Requests the signature from the oracle using the client sub-flow for signing from above.</li>
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<li>Adds the signature returned from the oracle.</li>
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</ol>
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<p>Here’s an example of it in action from <code class="docutils literal"><span class="pre">FixingFlow.Fixer</span></code>.</p>
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span> fun filterCommands(c: Command) = oracleParty.owningKey in c.signers && c.value is Fix
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val filterFuns = FilterFuns(filterCommands = ::filterCommands)
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val addFixing = object : RatesFixFlow(ptx, filterFuns, oracleParty, fixOf, BigDecimal.ZERO, BigDecimal.ONE) {
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span> val addFixing = object : RatesFixFlow(ptx, oracleParty, fixOf, BigDecimal.ZERO, BigDecimal.ONE) {
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@Suspendable
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override fun beforeSigning(fix: Fix) {
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newDeal.generateFix(ptx, StateAndRef(txState, handshake.payload.ref), fix)
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@ -590,10 +588,24 @@ called <code class="docutils literal"><span class="pre">RatesFixFlow</span></cod
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// to have one.
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ptx.setTime(serviceHub.clock.instant(), 30.seconds)
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}
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@Suspendable
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override fun filtering(elem: Any): Boolean {
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return when (elem) {
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is Command -> oracleParty.owningKey in elem.signers && elem.value is Fix
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else -> false
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}
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}
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}
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subFlow(addFixing)
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</pre></div>
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</div>
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<div class="admonition note">
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<p class="first admonition-title">Note</p>
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<p class="last">When overriding be careful when making the sub-class an anonymous or inner class (object declarations in Kotlin),
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because that kind of classes can access variables from the enclosing scope and cause serialization problems when
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checkpointed.</p>
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</div>
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</div>
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</div>
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Reference in New Issue
Block a user