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*** As of June 2017, the latest Solr Ref Guide is located at https://lucene.apache.org/solr/guide ***

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Code Block
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StreamContext context = new StreamContext()
SolrClientCache cache = new SolrClientCache();
context.setSolrClientCache(cache);

Map topicQueryParams = new HashMap();  
topicQueryParams.put("q","hello");  // The query for the topic
topicQueryparams.put("rows", "500"); // How many rows to fetch during each run
topicQueryparams.put("fl", "id, "title"); // The field list to return with the documents

TopicStream topicStream = new TopicStream(zkHost,        // Host address for the zookeeper service housing the collections 
                                         "checkpoints",  // The collection to store the topic checkpoints
                                         "topicData",    // The collection to query for the topic records
                                         "topicId",      // The id of the topic
                                         -1,             // checkpoint every X tuples, if set -1 it will checkpoint after each run.
                                          topicQueryParams); // The query parameters for the TopicStream

DaemonStream daemonStream = new DaemonStream(topicStream,             // The underlying stream to run. 
                                             "daemonId",              // The id of the daemon
                                             1000,                    // The interval at which to run the internal stream
                                             500);                    // The internal queue size for the daemon stream. Tuples will be placed in the queue
                                                                      // as they are read by the internal internal thread.
	                                                                  // Calling read() on the daemon stream reads records from the internal queue.
                                                                       
daemonStream.setStreamContext(context);

daemonStream.open();
 
//Read until it's time to shutdown the DaemonStream. You can define the shutdown criteria.
while(!shutdown()) {
    Tuple tuple = daemonStream.read() // This will block until tuples become available from the underlying stream (TopicStream)
                                      // The EOF tuple (signaling the end of the stream) will never occur until the DaemonStream has been shutdown.
    //Do something with the tuples
}
 
// Shutdown the DaemonStream.
daemonStream.shutdown();
 
//Read the DaemonStream until the EOF Tuple is found.
//This allows the underlying stream to perform an orderly shutdown.
 
while(true) {
    Tuple tuple = daemonStream.read();
    if(tuple.EOF) {
		break;
    } else {
		//Do something with the tuples.
	}
}
//Finally close the stream
daemonStream.close();

eval

executor

The executor function wraps a stream source that contains streaming expressions, and executes the expressions in parallel. The executor function looks for the expression in the expr_s field in each tuple. The executor function has an internal thread pool that runs tasks that compile and run expressions in parallel on the same worker node. This function can also be parallelized across worker nodes by wrapping it in the parallel  function to provide parallel execution of expressions across a cluster.

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