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<li class="toctree-l1 current"><a class="current reference internal" href="#">Client RPC API tutorial</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="#registering-classes-from-your-cordapp-with-rpc-kryo">Registering classes from your CorDapp with RPC Kryo</a></li>
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<li class="toctree-l1"><a class="reference internal" href="azure-vm.html">Working with the Corda Demo on Azure Marketplace</a></li>
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<div class="section" id="client-rpc-api-tutorial">
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<h1>Client RPC API tutorial<a class="headerlink" href="#client-rpc-api-tutorial" title="Permalink to this headline">¶</a></h1>
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<p>In this tutorial we will build a simple command line utility that
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connects to a node, creates some Cash transactions and meanwhile dumps
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the transaction graph to the standard output. We will then put some
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simple visualisation on top. For an explanation on how the RPC works
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see <a class="reference internal" href="clientrpc.html"><span class="doc">Client RPC</span></a>.</p>
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<p>We start off by connecting to the node itself. For the purposes of the tutorial we will use the Driver to start up a notary and a node that issues/exits and moves Cash around for herself. To authenticate we will use the certificates of the nodes directly.</p>
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<p>Note how we configure the node to create a user that has permission to start the CashFlow.</p>
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">enum</span> <span class="k">class</span> <span class="nc">PrintOrVisualise</span> <span class="p">{</span>
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<span class="n">Print</span><span class="p">,</span>
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<span class="n">Visualise</span>
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<span class="p">}</span>
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<span class="k">fun</span> <span class="nf">main</span><span class="p">(</span><span class="n">args</span><span class="p">:</span> <span class="n">Array</span><span class="p"><</span><span class="n">String</span><span class="p">>)</span> <span class="p">{</span>
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<span class="n">require</span><span class="p">(</span><span class="n">args</span><span class="p">.</span><span class="n">isNotEmpty</span><span class="p">())</span> <span class="p">{</span> <span class="s">"Usage: <binary> [Print|Visualise]"</span> <span class="p">}</span>
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<span class="k">val</span> <span class="py">printOrVisualise</span> <span class="p">=</span> <span class="n">PrintOrVisualise</span><span class="p">.</span><span class="n">valueOf</span><span class="p">(</span><span class="n">args</span><span class="p">[</span><span class="m">0</span><span class="p">])</span>
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<span class="k">val</span> <span class="py">baseDirectory</span> <span class="p">=</span> <span class="n">Paths</span><span class="p">.</span><span class="k">get</span><span class="p">(</span><span class="s">"build/rpc-api-tutorial"</span><span class="p">)</span>
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<span class="k">val</span> <span class="py">user</span> <span class="p">=</span> <span class="n">User</span><span class="p">(</span><span class="s">"user"</span><span class="p">,</span> <span class="s">"password"</span><span class="p">,</span> <span class="n">permissions</span> <span class="p">=</span> <span class="n">setOf</span><span class="p">(</span><span class="n">startFlowPermission</span><span class="p"><</span><span class="n">CashFlow</span><span class="p">>()))</span>
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<span class="n">driver</span><span class="p">(</span><span class="n">driverDirectory</span> <span class="p">=</span> <span class="n">baseDirectory</span><span class="p">)</span> <span class="p">{</span>
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<span class="n">startNode</span><span class="p">(</span><span class="s">"Notary"</span><span class="p">,</span> <span class="n">advertisedServices</span> <span class="p">=</span> <span class="n">setOf</span><span class="p">(</span><span class="n">ServiceInfo</span><span class="p">(</span><span class="n">ValidatingNotaryService</span><span class="p">.</span><span class="n">type</span><span class="p">)))</span>
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<span class="k">val</span> <span class="py">node</span> <span class="p">=</span> <span class="n">startNode</span><span class="p">(</span><span class="s">"Alice"</span><span class="p">,</span> <span class="n">rpcUsers</span> <span class="p">=</span> <span class="n">listOf</span><span class="p">(</span><span class="n">user</span><span class="p">)).</span><span class="k">get</span><span class="p">()</span>
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</pre></div>
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</div>
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<p>Now we can connect to the node itself using a valid RPC login. We login using the configured user.</p>
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span> <span class="k">val</span> <span class="py">client</span> <span class="p">=</span> <span class="n">node</span><span class="p">.</span><span class="n">rpcClientToNode</span><span class="p">()</span>
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<span class="n">client</span><span class="p">.</span><span class="n">start</span><span class="p">(</span><span class="s">"user"</span><span class="p">,</span> <span class="s">"password"</span><span class="p">)</span>
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<span class="k">val</span> <span class="py">proxy</span> <span class="p">=</span> <span class="n">client</span><span class="p">.</span><span class="n">proxy</span><span class="p">()</span>
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<span class="n">thread</span> <span class="p">{</span>
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<span class="n">generateTransactions</span><span class="p">(</span><span class="n">proxy</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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</div>
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<p>We start generating transactions in a different thread (<code class="docutils literal"><span class="pre">generateTransactions</span></code> to be defined later) using <code class="docutils literal"><span class="pre">proxy</span></code>, which exposes the full RPC interface of the node:</p>
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<div class="admonition warning">
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<p class="first admonition-title">Warning</p>
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<p class="last">This API is evolving and will continue to grow as new functionality and features added to Corda are made available to RPC clients.</p>
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</div>
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<p>The one we need in order to dump the transaction graph is <code class="docutils literal"><span class="pre">verifiedTransactions</span></code>. The type signature tells us that the
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RPC will return a list of transactions and an Observable stream. This is a general pattern, we query some data and the
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node will return the current snapshot and future updates done to it. Observables are described in further detail in
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<a class="reference internal" href="clientrpc.html"><span class="doc">Client RPC</span></a></p>
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span> val (transactions: List<SignedTransaction>, futureTransactions: Observable<SignedTransaction>) = proxy.verifiedTransactions()
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</pre></div>
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</div>
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<p>The graph will be defined by nodes and edges between them. Each node represents a transaction and edges represent
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output-input relations. For now let’s just print <code class="docutils literal"><span class="pre">NODE</span> <span class="pre"><txhash></span></code> for the former and <code class="docutils literal"><span class="pre">EDGE</span> <span class="pre"><txhash></span> <span class="pre"><txhash></span></code> for the
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latter.</p>
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span> <span class="k">when</span> <span class="p">(</span><span class="n">printOrVisualise</span><span class="p">)</span> <span class="p">{</span>
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<span class="n">PrintOrVisualise</span><span class="p">.</span><span class="n">Print</span> <span class="p">-></span> <span class="p">{</span>
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<span class="n">futureTransactions</span><span class="p">.</span><span class="n">startWith</span><span class="p">(</span><span class="n">transactions</span><span class="p">).</span><span class="n">subscribe</span> <span class="p">{</span> <span class="n">transaction</span> <span class="p">-></span>
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<span class="n">println</span><span class="p">(</span><span class="s">"NODE ${transaction.id}"</span><span class="p">)</span>
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<span class="n">transaction</span><span class="p">.</span><span class="n">tx</span><span class="p">.</span><span class="n">inputs</span><span class="p">.</span><span class="n">forEach</span> <span class="p">{</span> <span class="n">input</span> <span class="p">-></span>
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<span class="n">println</span><span class="p">(</span><span class="s">"EDGE ${input.txhash} ${transaction.id}"</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="p">}</span>
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</pre></div>
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</div>
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<p>Now we just need to create the transactions themselves!</p>
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">fun</span> <span class="nf">generateTransactions</span><span class="p">(</span><span class="n">proxy</span><span class="p">:</span> <span class="n">CordaRPCOps</span><span class="p">)</span> <span class="p">{</span>
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<span class="k">var</span> <span class="py">ownedQuantity</span> <span class="p">=</span> <span class="n">proxy</span><span class="p">.</span><span class="n">vaultAndUpdates</span><span class="p">().</span><span class="n">first</span><span class="p">.</span><span class="n">fold</span><span class="p">(</span><span class="m">0L</span><span class="p">)</span> <span class="p">{</span> <span class="n">sum</span><span class="p">,</span> <span class="n">state</span> <span class="p">-></span>
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<span class="n">sum</span> <span class="p">+</span> <span class="p">(</span><span class="n">state</span><span class="p">.</span><span class="n">state</span><span class="p">.</span><span class="k">data</span> <span class="k">as</span> <span class="n">Cash</span><span class="p">.</span><span class="n">State</span><span class="p">).</span><span class="n">amount</span><span class="p">.</span><span class="n">quantity</span>
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<span class="p">}</span>
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|
<span class="k">val</span> <span class="py">issueRef</span> <span class="p">=</span> <span class="n">OpaqueBytes</span><span class="p">.</span><span class="n">of</span><span class="p">(</span><span class="m">0</span><span class="p">)</span>
|
|
<span class="k">val</span> <span class="py">notary</span> <span class="p">=</span> <span class="n">proxy</span><span class="p">.</span><span class="n">networkMapUpdates</span><span class="p">().</span><span class="n">first</span><span class="p">.</span><span class="n">first</span> <span class="p">{</span> <span class="n">it</span><span class="p">.</span><span class="n">advertisedServices</span><span class="p">.</span><span class="n">any</span> <span class="p">{</span> <span class="n">it</span><span class="p">.</span><span class="n">info</span><span class="p">.</span><span class="n">type</span><span class="p">.</span><span class="n">isNotary</span><span class="p">()</span> <span class="p">}</span> <span class="p">}.</span><span class="n">notaryIdentity</span>
|
|
<span class="k">val</span> <span class="py">me</span> <span class="p">=</span> <span class="n">proxy</span><span class="p">.</span><span class="n">nodeIdentity</span><span class="p">().</span><span class="n">legalIdentity</span>
|
|
<span class="k">val</span> <span class="py">meAndRef</span> <span class="p">=</span> <span class="n">PartyAndReference</span><span class="p">(</span><span class="n">me</span><span class="p">,</span> <span class="n">issueRef</span><span class="p">)</span>
|
|
<span class="k">while</span> <span class="p">(</span><span class="k">true</span><span class="p">)</span> <span class="p">{</span>
|
|
<span class="n">Thread</span><span class="p">.</span><span class="n">sleep</span><span class="p">(</span><span class="m">1000</span><span class="p">)</span>
|
|
<span class="k">val</span> <span class="py">random</span> <span class="p">=</span> <span class="n">SplittableRandom</span><span class="p">()</span>
|
|
<span class="k">val</span> <span class="py">n</span> <span class="p">=</span> <span class="n">random</span><span class="p">.</span><span class="n">nextDouble</span><span class="p">()</span>
|
|
<span class="k">if</span> <span class="p">(</span><span class="n">ownedQuantity</span> <span class="p">></span> <span class="m">10000</span> <span class="p">&&</span> <span class="n">n</span> <span class="p">></span> <span class="m">0.8</span><span class="p">)</span> <span class="p">{</span>
|
|
<span class="k">val</span> <span class="py">quantity</span> <span class="p">=</span> <span class="n">Math</span><span class="p">.</span><span class="n">abs</span><span class="p">(</span><span class="n">random</span><span class="p">.</span><span class="n">nextLong</span><span class="p">())</span> <span class="p">%</span> <span class="m">2000</span>
|
|
<span class="n">proxy</span><span class="p">.</span><span class="n">startFlow</span><span class="p">(</span><span class="o">::</span><span class="n">CashFlow</span><span class="p">,</span> <span class="n">CashCommand</span><span class="p">.</span><span class="n">ExitCash</span><span class="p">(</span><span class="n">Amount</span><span class="p">(</span><span class="n">quantity</span><span class="p">,</span> <span class="n">USD</span><span class="p">),</span> <span class="n">issueRef</span><span class="p">))</span>
|
|
<span class="n">ownedQuantity</span> <span class="p">-=</span> <span class="n">quantity</span>
|
|
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span> <span class="p">(</span><span class="n">ownedQuantity</span> <span class="p">></span> <span class="m">1000</span> <span class="p">&&</span> <span class="n">n</span> <span class="p"><</span> <span class="m">0.7</span><span class="p">)</span> <span class="p">{</span>
|
|
<span class="k">val</span> <span class="py">quantity</span> <span class="p">=</span> <span class="n">Math</span><span class="p">.</span><span class="n">abs</span><span class="p">(</span><span class="n">random</span><span class="p">.</span><span class="n">nextLong</span><span class="p">()</span> <span class="p">%</span> <span class="n">Math</span><span class="p">.</span><span class="n">min</span><span class="p">(</span><span class="n">ownedQuantity</span><span class="p">,</span> <span class="m">2000</span><span class="p">))</span>
|
|
<span class="n">proxy</span><span class="p">.</span><span class="n">startFlow</span><span class="p">(</span><span class="o">::</span><span class="n">CashFlow</span><span class="p">,</span> <span class="n">CashCommand</span><span class="p">.</span><span class="n">PayCash</span><span class="p">(</span><span class="n">Amount</span><span class="p">(</span><span class="n">quantity</span><span class="p">,</span> <span class="n">Issued</span><span class="p">(</span><span class="n">meAndRef</span><span class="p">,</span> <span class="n">USD</span><span class="p">)),</span> <span class="n">me</span><span class="p">))</span>
|
|
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
|
|
<span class="k">val</span> <span class="py">quantity</span> <span class="p">=</span> <span class="n">Math</span><span class="p">.</span><span class="n">abs</span><span class="p">(</span><span class="n">random</span><span class="p">.</span><span class="n">nextLong</span><span class="p">()</span> <span class="p">%</span> <span class="m">1000</span><span class="p">)</span>
|
|
<span class="n">proxy</span><span class="p">.</span><span class="n">startFlow</span><span class="p">(</span><span class="o">::</span><span class="n">CashFlow</span><span class="p">,</span> <span class="n">CashCommand</span><span class="p">.</span><span class="n">IssueCash</span><span class="p">(</span><span class="n">Amount</span><span class="p">(</span><span class="n">quantity</span><span class="p">,</span> <span class="n">USD</span><span class="p">),</span> <span class="n">issueRef</span><span class="p">,</span> <span class="n">me</span><span class="p">,</span> <span class="n">notary</span><span class="p">))</span>
|
|
<span class="n">ownedQuantity</span> <span class="p">+=</span> <span class="n">quantity</span>
|
|
<span class="p">}</span>
|
|
<span class="p">}</span>
|
|
<span class="p">}</span>
|
|
</pre></div>
|
|
</div>
|
|
<p>We utilise several RPC functions here to query things like the notaries in the node cluster or our own vault.</p>
|
|
<p>Then in a loop we generate randomly either an Issue, a Pay or an Exit transaction.</p>
|
|
<p>The RPC we need to initiate a Cash transaction is <code class="docutils literal"><span class="pre">startFlowDynamic</span></code> which may start an arbitrary flow, given sufficient permissions to do so. We won’t use this function directly, but rather a type-safe wrapper around it <code class="docutils literal"><span class="pre">startFlow</span></code> that type-checks the arguments for us.</p>
|
|
<p>Finally we have everything in place: we start a couple of nodes, connect to them, and start creating transactions while listening on successfully created ones, which are dumped to the console. We just need to run it!:</p>
|
|
<div class="highlight-text"><div class="highlight"><pre><span></span># Build the example
|
|
./gradlew docs/source/example-code:installDist
|
|
# Start it
|
|
./docs/source/example-code/build/install/docs/source/example-code/bin/client-rpc-tutorial Print
|
|
</pre></div>
|
|
</div>
|
|
<p>Now let’s try to visualise the transaction graph. We will use a graph drawing library called <a class="reference external" href="http://graphstream-project.org/">graphstream</a></p>
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span> <span class="n">PrintOrVisualise</span><span class="p">.</span><span class="n">Visualise</span> <span class="p">-></span> <span class="p">{</span>
|
|
<span class="k">val</span> <span class="py">graph</span> <span class="p">=</span> <span class="n">MultiGraph</span><span class="p">(</span><span class="s">"transactions"</span><span class="p">)</span>
|
|
<span class="n">transactions</span><span class="p">.</span><span class="n">forEach</span> <span class="p">{</span> <span class="n">transaction</span> <span class="p">-></span>
|
|
<span class="n">graph</span><span class="p">.</span><span class="n">addNode</span><span class="p"><</span><span class="n">Node</span><span class="p">>(</span><span class="s">"${transaction.id}"</span><span class="p">)</span>
|
|
<span class="p">}</span>
|
|
<span class="n">transactions</span><span class="p">.</span><span class="n">forEach</span> <span class="p">{</span> <span class="n">transaction</span> <span class="p">-></span>
|
|
<span class="n">transaction</span><span class="p">.</span><span class="n">tx</span><span class="p">.</span><span class="n">inputs</span><span class="p">.</span><span class="n">forEach</span> <span class="p">{</span> <span class="n">ref</span> <span class="p">-></span>
|
|
<span class="n">graph</span><span class="p">.</span><span class="n">addEdge</span><span class="p"><</span><span class="n">Edge</span><span class="p">>(</span><span class="s">"$ref"</span><span class="p">,</span> <span class="s">"${ref.txhash}"</span><span class="p">,</span> <span class="s">"${transaction.id}"</span><span class="p">)</span>
|
|
<span class="p">}</span>
|
|
<span class="p">}</span>
|
|
<span class="n">futureTransactions</span><span class="p">.</span><span class="n">subscribe</span> <span class="p">{</span> <span class="n">transaction</span> <span class="p">-></span>
|
|
<span class="n">graph</span><span class="p">.</span><span class="n">addNode</span><span class="p"><</span><span class="n">Node</span><span class="p">>(</span><span class="s">"${transaction.id}"</span><span class="p">)</span>
|
|
<span class="n">transaction</span><span class="p">.</span><span class="n">tx</span><span class="p">.</span><span class="n">inputs</span><span class="p">.</span><span class="n">forEach</span> <span class="p">{</span> <span class="n">ref</span> <span class="p">-></span>
|
|
<span class="n">graph</span><span class="p">.</span><span class="n">addEdge</span><span class="p"><</span><span class="n">Edge</span><span class="p">>(</span><span class="s">"$ref"</span><span class="p">,</span> <span class="s">"${ref.txhash}"</span><span class="p">,</span> <span class="s">"${transaction.id}"</span><span class="p">)</span>
|
|
<span class="p">}</span>
|
|
<span class="p">}</span>
|
|
<span class="n">graph</span><span class="p">.</span><span class="n">display</span><span class="p">()</span>
|
|
<span class="p">}</span>
|
|
<span class="p">}</span>
|
|
<span class="n">waitForAllNodesToFinish</span><span class="p">()</span>
|
|
<span class="p">}</span>
|
|
|
|
<span class="p">}</span>
|
|
</pre></div>
|
|
</div>
|
|
<p>If we run the client with <code class="docutils literal"><span class="pre">Visualise</span></code> we should see a simple random graph being drawn as new transactions are being created.</p>
|
|
<div class="section" id="registering-classes-from-your-cordapp-with-rpc-kryo">
|
|
<h2>Registering classes from your CorDapp with RPC Kryo<a class="headerlink" href="#registering-classes-from-your-cordapp-with-rpc-kryo" title="Permalink to this headline">¶</a></h2>
|
|
<p>As described in <a class="reference internal" href="clientrpc.html"><span class="doc">Client RPC</span></a>, you currently have to register any additional classes you add that are needed in RPC
|
|
requests or responses with the <cite>Kryo</cite> instance RPC uses. Here’s an example of how you do this for an example class.</p>
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">data</span> <span class="k">class</span> <span class="nc">ExampleRPCValue</span><span class="p">(</span><span class="k">val</span> <span class="py">foo</span><span class="p">:</span> <span class="n">String</span><span class="p">)</span>
|
|
|
|
<span class="k">class</span> <span class="nc">ExampleRPCCordaPluginRegistry</span> <span class="p">:</span> <span class="n">CordaPluginRegistry</span><span class="p">()</span> <span class="p">{</span>
|
|
<span class="k">override</span> <span class="k">fun</span> <span class="nf">registerRPCKryoTypes</span><span class="p">(</span><span class="n">kryo</span><span class="p">:</span> <span class="n">Kryo</span><span class="p">):</span> <span class="n">Boolean</span> <span class="p">{</span>
|
|
<span class="c1">// Add classes like this.</span>
|
|
<span class="n">kryo</span><span class="p">.</span><span class="n">register</span><span class="p">(</span><span class="n">ExampleRPCValue</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="c1">// You should return true, otherwise your plugin will be ignored for registering classes with Kryo.</span>
|
|
<span class="k">return</span> <span class="k">true</span>
|
|
<span class="p">}</span>
|
|
<span class="p">}</span>
|
|
</pre></div>
|
|
</div>
|
|
<p>See more on plugins in <a class="reference internal" href="creating-a-cordapp.html"><span class="doc">CorDapp basics</span></a>.</p>
|
|
<div class="admonition warning">
|
|
<p class="first admonition-title">Warning</p>
|
|
<p class="last">We will be replacing the use of Kryo in RPC with a stable message format and this will mean that this plugin
|
|
customisation point will either go away completely or change.</p>
|
|
</div>
|
|
</div>
|
|
<div class="section" id="security">
|
|
<h2>Security<a class="headerlink" href="#security" title="Permalink to this headline">¶</a></h2>
|
|
<p>RPC credentials associated with a Client must match the permission set configured on the server Node.
|
|
This refers to both authentication (username and password) and role-based authorisation (a permissioned set of RPC operations an
|
|
authenticated user is entitled to run).</p>
|
|
<div class="admonition note">
|
|
<p class="first admonition-title">Note</p>
|
|
<p class="last">Permissions are represented as <em>String’s</em> to allow RPC implementations to add their own permissioning.
|
|
Currently the only permission type defined is <em>StartFlow</em>, which defines a list of whitelisted flows an authenticated use may execute.</p>
|
|
</div>
|
|
<p>In the instructions above the server node permissions are configured programmatically in the driver code:</p>
|
|
<div class="highlight-text"><div class="highlight"><pre><span></span>driver(driverDirectory = baseDirectory) {
|
|
val user = User("user", "password", permissions = setOf(startFlowPermission<CashFlow>()))
|
|
val node = startNode("Alice", rpcUsers = listOf(user)).get()
|
|
</pre></div>
|
|
</div>
|
|
<p>When starting a standalone node using a configuration file we must supply the RPC credentials as follows:</p>
|
|
<div class="highlight-text"><div class="highlight"><pre><span></span>rpcUsers : [
|
|
{ user=user, password=password, permissions=[ StartFlow.net.corda.flows.CashFlow ] }
|
|
]
|
|
</pre></div>
|
|
</div>
|
|
<p>When using the gradle Cordformation plugin to configure and deploy a node you must supply the RPC credentials in a similar manner:</p>
|
|
<div class="highlight-text"><div class="highlight"><pre><span></span>rpcUsers = [
|
|
['user' : "user",
|
|
'password' : "password",
|
|
'permissions' : ["StartFlow.net.corda.flows.CashFlow"]]
|
|
]
|
|
</pre></div>
|
|
</div>
|
|
<p>You can then deploy and launch the nodes (Notary and Alice) as follows:</p>
|
|
<div class="highlight-text"><div class="highlight"><pre><span></span># to create a set of configs and installs under ``docs/source/example-code/build/nodes`` run
|
|
./gradlew docs/source/example-code:deployNodes
|
|
# to open up two new terminals with the two nodes run
|
|
./docs/source/example-code/build/nodes/runnodes
|
|
# followed by the same commands as before:
|
|
./docs/source/example-code/build/install/docs/source/example-code/bin/client-rpc-tutorial Print
|
|
./docs/source/example-code/build/install/docs/source/example-code/bin/client-rpc-tutorial Visualise
|
|
</pre></div>
|
|
</div>
|
|
<p>See more on security in <a class="reference internal" href="secure-coding-guidelines.html"><span class="doc">Secure coding guidelines</span></a>, node configuration in <a class="reference internal" href="corda-configuration-file.html"><span class="doc">Node configuration</span></a> and
|
|
Cordformation in <a class="reference internal" href="creating-a-cordapp.html"><span class="doc">CorDapp basics</span></a></p>
|
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</div>
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</div>
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<footer>
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<a href="tutorial-building-transactions.html" class="btn btn-neutral float-right" title="Building transactions" accesskey="n">Next <span class="fa fa-arrow-circle-right"></span></a>
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