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| <div class="subTitle"><span class="packageLabelInType">Package</span> <a href="package-summary.html">org.apache.heron.api.spout</a></div> |
| <h2 title="Interface ISpout" class="title">Interface ISpout</h2> |
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| <dt>All Superinterfaces:</dt> |
| <dd><code>java.io.Serializable</code></dd> |
| </dl> |
| <dl> |
| <dt>All Known Subinterfaces:</dt> |
| <dd><code><a href="IRichSpout.html" title="interface in org.apache.heron.api.spout">IRichSpout</a></code></dd> |
| </dl> |
| <dl> |
| <dt>All Known Implementing Classes:</dt> |
| <dd><code><a href="../../integration_test/common/spout/ABSpout.html" title="class in org.apache.heron.integration_test.common.spout">ABSpout</a></code>, <code><a href="BaseRichSpout.html" title="class in org.apache.heron.api.spout">BaseRichSpout</a></code>, <code><a href="../../streamlet/impl/sources/ComplexSource.html" title="class in org.apache.heron.streamlet.impl.sources">ComplexSource</a></code>, <code><a href="../../integration_test/topology/serialization/CustomSpout.html" title="class in org.apache.heron.integration_test.topology.serialization">CustomSpout</a></code>, <code><a href="../../integration_test/common/spout/HdfsStringSpout.html" title="class in org.apache.heron.integration_test.common.spout">HdfsStringSpout</a></code>, <code><a href="../../scheduler/yarn/HeronExecutorTaskTest.TestSpout.html" title="class in org.apache.heron.scheduler.yarn">HeronExecutorTaskTest.TestSpout</a></code>, <code><a href="../HeronSubmitterTest.TestSpout.html" title="class in org.apache.heron.api">HeronSubmitterTest.TestSpout</a></code>, <code><a href="../HeronSubmitterTest.TestSpout2.html" title="class in org.apache.heron.api">HeronSubmitterTest.TestSpout2</a></code>, <code><a href="../../integration_test/core/IntegrationTestSpout.html" title="class in org.apache.heron.integration_test.core">IntegrationTestSpout</a></code>, <code><a href="../../../../../backtype/storm/topology/IRichSpoutDelegate.html" title="class in backtype.storm.topology">IRichSpoutDelegate</a></code>, <code><a href="../../../storm/topology/IRichSpoutDelegate.html" title="class in org.apache.storm.topology">IRichSpoutDelegate</a></code>, <code><a href="../../spouts/kafka/KafkaSpout.html" title="class in org.apache.heron.spouts.kafka">KafkaSpout</a></code>, <code><a href="../../integration_test/common/spout/LocalFileSpout.html" title="class in org.apache.heron.integration_test.common.spout">LocalFileSpout</a></code>, <code><a href="../../integration_test/common/spout/PausedLocalFileSpout.html" title="class in org.apache.heron.integration_test.common.spout">PausedLocalFileSpout</a></code>, <code><a href="../../integration_topology_test/common/spout/StatefulABSpout.html" title="class in org.apache.heron.integration_topology_test.common.spout">StatefulABSpout</a></code>, <code><a href="../../integration_test/core/StatefulIntegrationTestSpout.html" title="class in org.apache.heron.integration_test.core">StatefulIntegrationTestSpout</a></code>, <code><a href="../../integration_topology_test/core/StatefulIntegrationTopologyTestSpout.html" title="class in org.apache.heron.integration_topology_test.core">StatefulIntegrationTopologyTestSpout</a></code>, <code><a href="../../examples/eco/StatefulNumberSpout.html" title="class in org.apache.heron.examples.eco">StatefulNumberSpout</a></code>, <code><a href="../../examples/eco/StatefulRandomIntSpout.html" title="class in org.apache.heron.examples.eco">StatefulRandomIntSpout</a></code>, <code><a href="../../integration_topology_test/core/StatefulSpout.html" title="class in org.apache.heron.integration_topology_test.core">StatefulSpout</a></code>, <code><a href="../../integration_test/topology/windowing/stateful/StatefulWindowingTest.RandomSentenceSpout.html" title="class in org.apache.heron.integration_test.topology.windowing.stateful">StatefulWindowingTest.RandomSentenceSpout</a></code>, <code><a href="../../streamlet/impl/sources/StreamletSource.html" title="class in org.apache.heron.streamlet.impl.sources">StreamletSource</a></code>, <code><a href="../../streamlet/impl/sources/SupplierSource.html" title="class in org.apache.heron.streamlet.impl.sources">SupplierSource</a></code>, <code><a href="../../resource/TestSpout.html" title="class in org.apache.heron.resource">TestSpout</a></code>, <code><a href="../../resource/TestStatefulSpout.html" title="class in org.apache.heron.resource">TestStatefulSpout</a></code>, <code><a href="../../resource/TestTwoPhaseStatefulSpout.html" title="class in org.apache.heron.resource">TestTwoPhaseStatefulSpout</a></code>, <code><a href="../../integration_test/topology/serialization/UnserializableCustomSpout.html" title="class in org.apache.heron.integration_test.topology.serialization">UnserializableCustomSpout</a></code>, <code><a href="../../integration_test/topology/windowing/WindowTestBase.IncrementingSpout.html" title="class in org.apache.heron.integration_test.topology.windowing">WindowTestBase.IncrementingSpout</a></code>, <code><a href="../../examples/eco/WordSpout.html" title="class in org.apache.heron.examples.eco">WordSpout</a></code></dd> |
| </dl> |
| <hr> |
| <pre>public interface <span class="typeNameLabel">ISpout</span> |
| extends java.io.Serializable</pre> |
| <div class="block">ISpout is the core interface for implementing spouts. A Spout is responsible |
| for feeding messages into the topology for processing. For every tuple emitted by |
| a spout, Heron will track the (potentially very large) DAG of tuples generated |
| based on a tuple emitted by the spout. When Heron detects that every tuple in |
| that DAG has been successfully processed, it will send an ack message to the Spout. |
| <p> |
| <p>If a tuple fails to be fully process within the configured timeout for the |
| topology (see <a href="../Config.html" title="class in org.apache.heron.api"><code>Config</code></a>), Heron will send a fail |
| message to the spout |
| for the message.</p> |
| <p> |
| <p> When a Spout emits a tuple, it can tag the tuple with a message id. The message id |
| can be any type. When Heron acks or fails a message, it will pass back to the |
| spout the same message id to identify which tuple it's referring to. If the spout leaves out |
| the message id, or sets it to null, then Heron will not track the message and the spout |
| will not receive any ack or fail callbacks for the message.</p> |
| <p> |
| <p>Heron executes ack, fail, and nextTuple all on the same thread. This means that an implementor |
| of an ISpout does not need to worry about concurrency issues between those methods. However, it |
| also means that an implementor must ensure that nextTuple is non-blocking: otherwise |
| the method could await acks and fails that are pending to be processed.</p></div> |
| </li> |
| </ul> |
| </div> |
| <div class="summary"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- ========== METHOD SUMMARY =========== --> |
| <section> |
| <ul class="blockList"> |
| <li class="blockList"><a id="method.summary"> |
| <!-- --> |
| </a> |
| <h3>Method Summary</h3> |
| <table class="memberSummary"> |
| <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="colSecond" scope="col">Method</th> |
| <th class="colLast" scope="col">Description</th> |
| </tr> |
| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#ack(java.lang.Object)">ack</a></span>​(java.lang.Object msgId)</code></th> |
| <td class="colLast"> |
| <div class="block">Heron has determined that the tuple emitted by this spout with the msgId identifier |
| has been fully processed.</div> |
| </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code>void</code></td> |
| <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#activate()">activate</a></span>()</code></th> |
| <td class="colLast"> |
| <div class="block">Called when a spout has been activated out of a deactivated mode.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#close()">close</a></span>()</code></th> |
| <td class="colLast"> |
| <div class="block">Called when an ISpout is going to be shutdown.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code>void</code></td> |
| <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#deactivate()">deactivate</a></span>()</code></th> |
| <td class="colLast"> |
| <div class="block">Called when a spout has been deactivated.</div> |
| </td> |
| </tr> |
| <tr id="i4" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#fail(java.lang.Object)">fail</a></span>​(java.lang.Object msgId)</code></th> |
| <td class="colLast"> |
| <div class="block">The tuple emitted by this spout with the msgId identifier has failed to be |
| fully processed.</div> |
| </td> |
| </tr> |
| <tr id="i5" class="rowColor"> |
| <td class="colFirst"><code>void</code></td> |
| <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#nextTuple()">nextTuple</a></span>()</code></th> |
| <td class="colLast"> |
| <div class="block">When this method is called, Heron is requesting that the Spout emit tuples to the |
| output collector.</div> |
| </td> |
| </tr> |
| <tr id="i6" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <th class="colSecond" scope="row"><code><span class="memberNameLink"><a href="#open(java.util.Map,org.apache.heron.api.topology.TopologyContext,org.apache.heron.api.spout.SpoutOutputCollector)">open</a></span>​(java.util.Map<java.lang.String,​java.lang.Object> conf, |
| <a href="../topology/TopologyContext.html" title="interface in org.apache.heron.api.topology">TopologyContext</a> context, |
| <a href="SpoutOutputCollector.html" title="class in org.apache.heron.api.spout">SpoutOutputCollector</a> collector)</code></th> |
| <td class="colLast"> |
| <div class="block">Called when a task for this component is initialized within a worker on the cluster.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
| </ul> |
| </section> |
| </li> |
| </ul> |
| </div> |
| <div class="details"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <!-- ============ METHOD DETAIL ========== --> |
| <section> |
| <ul class="blockList"> |
| <li class="blockList"><a id="method.detail"> |
| <!-- --> |
| </a> |
| <h3>Method Detail</h3> |
| <a id="open(java.util.Map,org.apache.heron.api.topology.TopologyContext,org.apache.heron.api.spout.SpoutOutputCollector)"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>open</h4> |
| <pre class="methodSignature">void open​(java.util.Map<java.lang.String,​java.lang.Object> conf, |
| <a href="../topology/TopologyContext.html" title="interface in org.apache.heron.api.topology">TopologyContext</a> context, |
| <a href="SpoutOutputCollector.html" title="class in org.apache.heron.api.spout">SpoutOutputCollector</a> collector)</pre> |
| <div class="block">Called when a task for this component is initialized within a worker on the cluster. |
| It provides the spout with the environment in which the spout executes. |
| <p> |
| <p>This includes the:</p></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>conf</code> - The Heron configuration for this spout. This is the configuration provided to the topology merged in with cluster configuration on this machine.</dd> |
| <dd><code>context</code> - This object can be used to get information about this task's place within the topology, including the task id and component id of this task, input and output information, etc.</dd> |
| <dd><code>collector</code> - The collector is used to emit tuples from this spout. Tuples can be emitted at any time, including the open and close methods. The collector is thread-safe and should be saved as an instance variable of this spout object.</dd> |
| </dl> |
| </li> |
| </ul> |
| <a id="close()"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>close</h4> |
| <pre class="methodSignature">void close()</pre> |
| <div class="block">Called when an ISpout is going to be shutdown. There is no guarentee that close |
| will be called, because the supervisor kill -9's worker processes on the cluster. |
| <p> |
| <p>The one context where close is guaranteed to be called is a topology is |
| killed when running Heron in simulator.</p></div> |
| </li> |
| </ul> |
| <a id="activate()"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>activate</h4> |
| <pre class="methodSignature">void activate()</pre> |
| <div class="block">Called when a spout has been activated out of a deactivated mode. |
| nextTuple will be called on this spout soon. A spout can become activated |
| after having been deactivated when the topology is manipulated using the |
| `heron` client.</div> |
| </li> |
| </ul> |
| <a id="deactivate()"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>deactivate</h4> |
| <pre class="methodSignature">void deactivate()</pre> |
| <div class="block">Called when a spout has been deactivated. nextTuple will not be called while |
| a spout is deactivated. The spout may or may not be reactivated in the future.</div> |
| </li> |
| </ul> |
| <a id="nextTuple()"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>nextTuple</h4> |
| <pre class="methodSignature">void nextTuple()</pre> |
| <div class="block">When this method is called, Heron is requesting that the Spout emit tuples to the |
| output collector. This method should be non-blocking, so if the Spout has no tuples |
| to emit, this method should return. nextTuple, ack, and fail are all called in a tight |
| loop in a single thread in the spout task. When there are no tuples to emit, it is courteous |
| to have nextTuple sleep for a short amount of time (like a single millisecond) |
| so as not to waste too much CPU.</div> |
| </li> |
| </ul> |
| <a id="ack(java.lang.Object)"> |
| <!-- --> |
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| <h4>ack</h4> |
| <pre class="methodSignature">void ack​(java.lang.Object msgId)</pre> |
| <div class="block">Heron has determined that the tuple emitted by this spout with the msgId identifier |
| has been fully processed. Typically, an implementation of this method will take that |
| message off the queue and prevent it from being replayed.</div> |
| </li> |
| </ul> |
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| <!-- --> |
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| <li class="blockList"> |
| <h4>fail</h4> |
| <pre class="methodSignature">void fail​(java.lang.Object msgId)</pre> |
| <div class="block">The tuple emitted by this spout with the msgId identifier has failed to be |
| fully processed. Typically, an implementation of this method will put that |
| message back on the queue to be replayed at a later time.</div> |
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