| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <!-- NewPage --> |
| <html lang="en"> |
| <head> |
| <!-- Generated by javadoc --> |
| <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> |
| <title>Function (Storm 2.4.0 API)</title> |
| <link rel="stylesheet" type="text/css" href="../../../../../stylesheet.css" title="Style"> |
| <script type="text/javascript" src="../../../../../script.js"></script> |
| </head> |
| <body> |
| <script type="text/javascript"><!-- |
| try { |
| if (location.href.indexOf('is-external=true') == -1) { |
| parent.document.title="Function (Storm 2.4.0 API)"; |
| } |
| } |
| catch(err) { |
| } |
| //--> |
| var methods = {"i0":6}; |
| var tabs = {65535:["t0","All Methods"],2:["t2","Instance Methods"],4:["t3","Abstract Methods"]}; |
| var altColor = "altColor"; |
| var rowColor = "rowColor"; |
| var tableTab = "tableTab"; |
| var activeTableTab = "activeTableTab"; |
| </script> |
| <noscript> |
| <div>JavaScript is disabled on your browser.</div> |
| </noscript> |
| <!-- ========= START OF TOP NAVBAR ======= --> |
| <div class="topNav"><a name="navbar.top"> |
| <!-- --> |
| </a> |
| <div class="skipNav"><a href="#skip.navbar.top" title="Skip navigation links">Skip navigation links</a></div> |
| <a name="navbar.top.firstrow"> |
| <!-- --> |
| </a> |
| <ul class="navList" title="Navigation"> |
| <li><a href="../../../../../overview-summary.html">Overview</a></li> |
| <li><a href="package-summary.html">Package</a></li> |
| <li class="navBarCell1Rev">Class</li> |
| <li><a href="class-use/Function.html">Use</a></li> |
| <li><a href="package-tree.html">Tree</a></li> |
| <li><a href="../../../../../deprecated-list.html">Deprecated</a></li> |
| <li><a href="../../../../../index-all.html">Index</a></li> |
| <li><a href="../../../../../help-doc.html">Help</a></li> |
| </ul> |
| </div> |
| <div class="subNav"> |
| <ul class="navList"> |
| <li><a href="../../../../../org/apache/storm/trident/operation/FlatMapFunction.html" title="interface in org.apache.storm.trident.operation"><span class="typeNameLink">Prev Class</span></a></li> |
| <li><a href="../../../../../org/apache/storm/trident/operation/GroupedMultiReducer.html" title="interface in org.apache.storm.trident.operation"><span class="typeNameLink">Next Class</span></a></li> |
| </ul> |
| <ul class="navList"> |
| <li><a href="../../../../../index.html?org/apache/storm/trident/operation/Function.html" target="_top">Frames</a></li> |
| <li><a href="Function.html" target="_top">No Frames</a></li> |
| </ul> |
| <ul class="navList" id="allclasses_navbar_top"> |
| <li><a href="../../../../../allclasses-noframe.html">All Classes</a></li> |
| </ul> |
| <div> |
| <script type="text/javascript"><!-- |
| allClassesLink = document.getElementById("allclasses_navbar_top"); |
| if(window==top) { |
| allClassesLink.style.display = "block"; |
| } |
| else { |
| allClassesLink.style.display = "none"; |
| } |
| //--> |
| </script> |
| </div> |
| <div> |
| <ul class="subNavList"> |
| <li>Summary: </li> |
| <li>Nested | </li> |
| <li>Field | </li> |
| <li>Constr | </li> |
| <li><a href="#method.summary">Method</a></li> |
| </ul> |
| <ul class="subNavList"> |
| <li>Detail: </li> |
| <li>Field | </li> |
| <li>Constr | </li> |
| <li><a href="#method.detail">Method</a></li> |
| </ul> |
| </div> |
| <a name="skip.navbar.top"> |
| <!-- --> |
| </a></div> |
| <!-- ========= END OF TOP NAVBAR ========= --> |
| <!-- ======== START OF CLASS DATA ======== --> |
| <div class="header"> |
| <div class="subTitle">org.apache.storm.trident.operation</div> |
| <h2 title="Interface Function" class="title">Interface Function</h2> |
| </div> |
| <div class="contentContainer"> |
| <div class="description"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <dl> |
| <dt>All Superinterfaces:</dt> |
| <dd><a href="../../../../../org/apache/storm/trident/operation/EachOperation.html" title="interface in org.apache.storm.trident.operation">EachOperation</a>, <a href="../../../../../org/apache/storm/trident/operation/Operation.html" title="interface in org.apache.storm.trident.operation">Operation</a>, <a href="https://docs.oracle.com/javase/8/docs/api/java/io/Serializable.html?is-external=true" title="class or interface in java.io">Serializable</a></dd> |
| </dl> |
| <dl> |
| <dt>All Known Implementing Classes:</dt> |
| <dd><a href="../../../../../org/apache/storm/trident/operation/BaseFunction.html" title="class in org.apache.storm.trident.operation">BaseFunction</a>, <a href="../../../../../org/apache/storm/trident/operation/impl/CombinerAggregatorInitImpl.html" title="class in org.apache.storm.trident.operation.impl">CombinerAggregatorInitImpl</a>, <a href="../../../../../org/apache/storm/trident/operation/impl/ConsumerExecutor.html" title="class in org.apache.storm.trident.operation.impl">ConsumerExecutor</a>, <a href="../../../../../org/apache/storm/trident/operation/impl/FilterExecutor.html" title="class in org.apache.storm.trident.operation.impl">FilterExecutor</a>, <a href="../../../../../org/apache/storm/trident/operation/impl/FlatMapFunctionExecutor.html" title="class in org.apache.storm.trident.operation.impl">FlatMapFunctionExecutor</a>, <a href="../../../../../org/apache/storm/trident/operation/impl/MapFunctionExecutor.html" title="class in org.apache.storm.trident.operation.impl">MapFunctionExecutor</a>, <a href="../../../../../org/apache/storm/mqtt/trident/MqttPublishFunction.html" title="class in org.apache.storm.mqtt.trident">MqttPublishFunction</a>, <a href="../../../../../org/apache/storm/mongodb/trident/PrintFunction.html" title="class in org.apache.storm.mongodb.trident">PrintFunction</a>, <a href="../../../../../org/apache/storm/redis/trident/PrintFunction.html" title="class in org.apache.storm.redis.trident">PrintFunction</a>, <a href="../../../../../org/apache/storm/hbase/trident/PrintFunction.html" title="class in org.apache.storm.hbase.trident">PrintFunction</a>, <a href="../../../../../org/apache/storm/trident/testing/Split.html" title="class in org.apache.storm.trident.testing">Split</a>, <a href="../../../../../org/apache/storm/trident/testing/StringLength.html" title="class in org.apache.storm.trident.testing">StringLength</a>, <a href="../../../../../org/apache/storm/starter/trident/TridentReach.ExpandList.html" title="class in org.apache.storm.starter.trident">TridentReach.ExpandList</a>, <a href="../../../../../org/apache/storm/starter/trident/TridentWordCount.Split.html" title="class in org.apache.storm.starter.trident">TridentWordCount.Split</a>, <a href="../../../../../org/apache/storm/trident/testing/TuplifyArgs.html" title="class in org.apache.storm.trident.testing">TuplifyArgs</a></dd> |
| </dl> |
| <hr> |
| <br> |
| <pre>public interface <span class="typeNameLabel">Function</span> |
| extends <a href="../../../../../org/apache/storm/trident/operation/EachOperation.html" title="interface in org.apache.storm.trident.operation">EachOperation</a></pre> |
| <div class="block"><p>A function takes in a set of input fields and emits zero or more tuples as output. The fields of the output tuple are appended to the original input tuple in the stream. If a function emits no tuples, the original input tuple is filtered out. Otherwise, the input tuple is duplicated for each output tuple.</p><p><p>For example, if you have the following function:</p><p><p><code>java public class MyFunction extends BaseFunction { public void execute(TridentTuple tuple, TridentCollector collector) |
| { for(int i=0; i < tuple.getInteger(0); i++) { collector.emit(new Values(i)); } } } |
| </code></p><p><p>Now suppose you have a stream in the variable <code>mystream</code> with the fields <code>["a", "b", "c"]</code> with the following tuples:</p><p><p><code>[1, 2, 3] [4, 1, 6] [3, 0, 8]</code> If you had the following code in your topology definition:</p><p><p><code>java mystream.each(new Fields("b"), new MyFunction(), new Fields("d")))</code></p><p><p>The resulting tuples would have the fields <code>["a", "b", "c", "d"]</code> and look like this:</p><p><p><code>[1, 2, 3, 0] [1, 2, 3, 1] [4, 1, 6, 0]</code></p><p><p>In this case, the parameter <code>new Fields("b")</code> tells Trident that you would like to select the field “b” as input to the function, and that will be the only field in the Tuple passed to the <code>execute()</code> method. The value of “b” in the first tuple (2) causes the for loop to execute twice, so 2 tuples are emitted. similarly the second tuple causes one tuple to be emitted. For the third tuple, the value of 0 causes the <code>for</code> loop to be skipped, so nothing is emitted and the incoming tuple is filtered out of the stream.</p><p><p>### Configuration If your <code>Function</code> implementation has configuration requirements, you will typically want to extend <a href="../../../../../org/apache/storm/trident/operation/BaseFunction.html" title="class in org.apache.storm.trident.operation"><code>BaseFunction</code></a> and override the <a href="../../../../../org/apache/storm/trident/operation/Operation.html#prepare-java.util.Map-org.apache.storm.trident.operation.TridentOperationContext-"><code>Operation.prepare(Map, |
| TridentOperationContext)</code></a> method to perform your custom initialization.</p><p><p>### Performance Considerations Because Trident Functions perform logic on individual tuples – as opposed to batches – it is advisable to avoid expensive operations such as database operations in a Function, if possible. For data store interactions it is better to use a <a href="../../../../../org/apache/storm/trident/state/State.html" title="interface in org.apache.storm.trident.state"><code>State</code></a> or <a href="../../../../../org/apache/storm/trident/state/QueryFunction.html" title="interface in org.apache.storm.trident.state"><code>QueryFunction</code></a> implementation since Trident states operate on batch partitions and can perform bulk updates to a database.</p></div> |
| </li> |
| </ul> |
| </div> |
| <div class="summary"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- ========== METHOD SUMMARY =========== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="method.summary"> |
| <!-- --> |
| </a> |
| <h3>Method Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> |
| <caption><span id="t0" class="activeTableTab"><span>All Methods</span><span class="tabEnd"> </span></span><span id="t2" class="tableTab"><span><a href="javascript:show(2);">Instance Methods</a></span><span class="tabEnd"> </span></span><span id="t3" class="tableTab"><span><a href="javascript:show(4);">Abstract Methods</a></span><span class="tabEnd"> </span></span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Method and Description</th> |
| </tr> |
| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/storm/trident/operation/Function.html#execute-org.apache.storm.trident.tuple.TridentTuple-org.apache.storm.trident.operation.TridentCollector-">execute</a></span>(<a href="../../../../../org/apache/storm/trident/tuple/TridentTuple.html" title="interface in org.apache.storm.trident.tuple">TridentTuple</a> tuple, |
| <a href="../../../../../org/apache/storm/trident/operation/TridentCollector.html" title="interface in org.apache.storm.trident.operation">TridentCollector</a> collector)</code> |
| <div class="block">Performs the function logic on an individual tuple and emits 0 or more tuples.</div> |
| </td> |
| </tr> |
| </table> |
| <ul class="blockList"> |
| <li class="blockList"><a name="methods.inherited.from.class.org.apache.storm.trident.operation.Operation"> |
| <!-- --> |
| </a> |
| <h3>Methods inherited from interface org.apache.storm.trident.operation.<a href="../../../../../org/apache/storm/trident/operation/Operation.html" title="interface in org.apache.storm.trident.operation">Operation</a></h3> |
| <code><a href="../../../../../org/apache/storm/trident/operation/Operation.html#cleanup--">cleanup</a>, <a href="../../../../../org/apache/storm/trident/operation/Operation.html#prepare-java.util.Map-org.apache.storm.trident.operation.TridentOperationContext-">prepare</a></code></li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| <div class="details"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- ============ METHOD DETAIL ========== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="method.detail"> |
| <!-- --> |
| </a> |
| <h3>Method Detail</h3> |
| <a name="execute-org.apache.storm.trident.tuple.TridentTuple-org.apache.storm.trident.operation.TridentCollector-"> |
| <!-- --> |
| </a> |
| <ul class="blockListLast"> |
| <li class="blockList"> |
| <h4>execute</h4> |
| <pre>void execute(<a href="../../../../../org/apache/storm/trident/tuple/TridentTuple.html" title="interface in org.apache.storm.trident.tuple">TridentTuple</a> tuple, |
| <a href="../../../../../org/apache/storm/trident/operation/TridentCollector.html" title="interface in org.apache.storm.trident.operation">TridentCollector</a> collector)</pre> |
| <div class="block"><p>Performs the function logic on an individual tuple and emits 0 or more tuples.</p></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>tuple</code> - The incoming tuple</dd> |
| <dd><code>collector</code> - A collector instance that can be used to emit tuples</dd> |
| </dl> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| </div> |
| <!-- ========= END OF CLASS DATA ========= --> |
| <!-- ======= START OF BOTTOM NAVBAR ====== --> |
| <div class="bottomNav"><a name="navbar.bottom"> |
| <!-- --> |
| </a> |
| <div class="skipNav"><a href="#skip.navbar.bottom" title="Skip navigation links">Skip navigation links</a></div> |
| <a name="navbar.bottom.firstrow"> |
| <!-- --> |
| </a> |
| <ul class="navList" title="Navigation"> |
| <li><a href="../../../../../overview-summary.html">Overview</a></li> |
| <li><a href="package-summary.html">Package</a></li> |
| <li class="navBarCell1Rev">Class</li> |
| <li><a href="class-use/Function.html">Use</a></li> |
| <li><a href="package-tree.html">Tree</a></li> |
| <li><a href="../../../../../deprecated-list.html">Deprecated</a></li> |
| <li><a href="../../../../../index-all.html">Index</a></li> |
| <li><a href="../../../../../help-doc.html">Help</a></li> |
| </ul> |
| <div class="aboutLanguage"><script type="text/javascript" src="../../../../../highlight.pack.js"></script> |
| <script type="text/javascript"><!-- |
| hljs.initHighlightingOnLoad(); |
| //--></script></div> |
| </div> |
| <div class="subNav"> |
| <ul class="navList"> |
| <li><a href="../../../../../org/apache/storm/trident/operation/FlatMapFunction.html" title="interface in org.apache.storm.trident.operation"><span class="typeNameLink">Prev Class</span></a></li> |
| <li><a href="../../../../../org/apache/storm/trident/operation/GroupedMultiReducer.html" title="interface in org.apache.storm.trident.operation"><span class="typeNameLink">Next Class</span></a></li> |
| </ul> |
| <ul class="navList"> |
| <li><a href="../../../../../index.html?org/apache/storm/trident/operation/Function.html" target="_top">Frames</a></li> |
| <li><a href="Function.html" target="_top">No Frames</a></li> |
| </ul> |
| <ul class="navList" id="allclasses_navbar_bottom"> |
| <li><a href="../../../../../allclasses-noframe.html">All Classes</a></li> |
| </ul> |
| <div> |
| <script type="text/javascript"><!-- |
| allClassesLink = document.getElementById("allclasses_navbar_bottom"); |
| if(window==top) { |
| allClassesLink.style.display = "block"; |
| } |
| else { |
| allClassesLink.style.display = "none"; |
| } |
| //--> |
| </script> |
| </div> |
| <div> |
| <ul class="subNavList"> |
| <li>Summary: </li> |
| <li>Nested | </li> |
| <li>Field | </li> |
| <li>Constr | </li> |
| <li><a href="#method.summary">Method</a></li> |
| </ul> |
| <ul class="subNavList"> |
| <li>Detail: </li> |
| <li>Field | </li> |
| <li>Constr | </li> |
| <li><a href="#method.detail">Method</a></li> |
| </ul> |
| </div> |
| <a name="skip.navbar.bottom"> |
| <!-- --> |
| </a></div> |
| <!-- ======== END OF BOTTOM NAVBAR ======= --> |
| <p class="legalCopy"><small>Copyright © 2022 <a href="https://www.apache.org/">The Apache Software Foundation</a>. All rights reserved.</small></p> |
| </body> |
| </html> |
