content/releases/0.7.1/api/java/io/gearpump/streaming/source/DataSource.html - incubator-retired-gearpump-site - Git at Google

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 <pre>public interface <strong>DataSource</strong>
 extends java.io.Serializable</pre>
 <div class="block">interface to implement custom source where data is read into the system.
  a DataSource could be a message queue like kafka or simply data generation source.
  <p>
  an example would be like
  <pre><code>
   GenStringSource extends DataSource {

     def open(context: TaskContext, startTime: Option[TimeStamp]): Unit = {}

     def read(batchSize: Int): List[Message] = {
       List.fill(batchSize)(Message("message"))
     }

     def close(): Unit = {}
   }
  </code></pre>
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  subclass is required to be serializable</div>
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 <td class="colFirst"><code>void</code></td>
 <td class="colLast"><code><strong><a href="../../../../io/gearpump/streaming/source/DataSource.html#close()">close</a></strong>()</code>
 <div class="block">close connection to data source.</div>
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 <td class="colFirst"><code>void</code></td>
 <td class="colLast"><code><strong><a href="../../../../io/gearpump/streaming/source/DataSource.html#open(io.gearpump.streaming.task.TaskContext, scala.Option)">open</a></strong>(<a href="../../../../io/gearpump/streaming/task/TaskContext.html" title="interface in io.gearpump.streaming.task">TaskContext</a>&nbsp;context,
     scala.Option&lt;java.lang.Object&gt;&nbsp;startTime)</code>
 <div class="block">open connection to data source
  invoked in onStart() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
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 <td class="colFirst"><code>scala.collection.immutable.List&lt;io.gearpump.Message&gt;</code></td>
 <td class="colLast"><code><strong><a href="../../../../io/gearpump/streaming/source/DataSource.html#read(int)">read</a></strong>(int&nbsp;batchSize)</code>
 <div class="block">read a number of messages from data source.</div>
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 <h4>open</h4>
 <pre>void&nbsp;open(<a href="../../../../io/gearpump/streaming/task/TaskContext.html" title="interface in io.gearpump.streaming.task">TaskContext</a>&nbsp;context,
         scala.Option&lt;java.lang.Object&gt;&nbsp;startTime)</pre>
 <div class="block">open connection to data source
  invoked in onStart() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
 <dl><dt><span class="strong">Parameters:</span></dt><dd><code>context</code> - is the task context at runtime</dd><dd><code>startTime</code> - is the start time of system</dd></dl>
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 <pre>scala.collection.immutable.List&lt;io.gearpump.Message&gt;&nbsp;read(int&nbsp;batchSize)</pre>
 <div class="block">read a number of messages from data source.
  invoked in each onNext() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
 <dl><dt><span class="strong">Parameters:</span></dt><dd><code>batchSize</code> - max number of messages to read</dd>
 <dt><span class="strong">Returns:</span></dt><dd>a list of messages wrapped in <code>Message</code></dd></dl>
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 <pre>void&nbsp;close()</pre>
 <div class="block">close connection to data source.
  invoked in onStop() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
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	<pre>public interface <strong>DataSource</strong>
	extends java.io.Serializable</pre>
	<div class="block">interface to implement custom source where data is read into the system.
	a DataSource could be a message queue like kafka or simply data generation source.
	<p>
	an example would be like
	<pre><code>
	GenStringSource extends DataSource {

	def open(context: TaskContext, startTime: Option[TimeStamp]): Unit = {}

	def read(batchSize: Int): List[Message] = {
	List.fill(batchSize)(Message("message"))
	}

	def close(): Unit = {}
	}
	</code></pre>
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	subclass is required to be serializable</div>
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	<td class="colFirst"><code>void</code></td>
	<td class="colLast"><code><strong><a href="../../../../io/gearpump/streaming/source/DataSource.html#close()">close</a></strong>()</code>
	<div class="block">close connection to data source.</div>
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	<td class="colFirst"><code>void</code></td>
	<td class="colLast"><code><strong><a href="../../../../io/gearpump/streaming/source/DataSource.html#open(io.gearpump.streaming.task.TaskContext, scala.Option)">open</a></strong>(<a href="../../../../io/gearpump/streaming/task/TaskContext.html" title="interface in io.gearpump.streaming.task">TaskContext</a> context,
	scala.Option<java.lang.Object> startTime)</code>
	<div class="block">open connection to data source
	invoked in onStart() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
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	<td class="colFirst"><code>scala.collection.immutable.List<io.gearpump.Message></code></td>
	<td class="colLast"><code><strong><a href="../../../../io/gearpump/streaming/source/DataSource.html#read(int)">read</a></strong>(int batchSize)</code>
	<div class="block">read a number of messages from data source.</div>
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	<h4>open</h4>
	<pre>void open(<a href="../../../../io/gearpump/streaming/task/TaskContext.html" title="interface in io.gearpump.streaming.task">TaskContext</a> context,
	scala.Option<java.lang.Object> startTime)</pre>
	<div class="block">open connection to data source
	invoked in onStart() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
	<dl><dt><span class="strong">Parameters:</span></dt><dd><code>context</code> - is the task context at runtime</dd><dd><code>startTime</code> - is the start time of system</dd></dl>
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	<pre>scala.collection.immutable.List<io.gearpump.Message> read(int batchSize)</pre>
	<div class="block">read a number of messages from data source.
	invoked in each onNext() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
	<dl><dt><span class="strong">Parameters:</span></dt><dd><code>batchSize</code> - max number of messages to read</dd>
	<dt><span class="strong">Returns:</span></dt><dd>a list of messages wrapped in <code>Message</code></dd></dl>
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	<pre>void close()</pre>
	<div class="block">close connection to data source.
	invoked in onStop() method of <a href="../../../../io/gearpump/streaming/source/DataSourceTask.html" title="class in io.gearpump.streaming.source"><code>DataSourceTask</code></a></div>
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