Getting Started - Getting Started with Storm - page 11

}
}
/**
* We will create the file and get the collector object
*/
public void open ( Map conf , TopologyContext context ,
SpoutOutputCollector collector ) {
try {
this . context = context ;
this . fileReader = new FileReader ( conf . get ( "wordsFile" ). toString ());
} catch ( FileNotFoundException e ) {
throw new RuntimeException ( "Error reading file
[" + conf . get ( "wordFile" )+ "]" );
}
this . collector = collector ;
}
/**
* Declare the output field "word"
*/
public void declareOutputFields ( OutputFieldsDeclarer declarer ) {
declarer . declare ( new Fields ( "line" ));
}
}
The first method called in any spout is public void open(Map conf, TopologyContext
context, SpoutOutputCollector collector) . The parameters it receives are the Topo-
logyContext, which contains all our topology data; the conf object, which is created in
the topology definition; and the SpoutOutputCollector, which enables us to emit the
data that will be processed by the bolts. The following code block is the open method
implementation:
public void open ( Map conf , TopologyContext context ,
SpoutOutputCollector collector ) {
try {
this . context = context ;
this . fileReader = new FileReader ( conf . get ( "wordsFile" ). toString ());
} catch ( FileNotFoundException e ) {
throw new RuntimeException ( "Error reading file [" + conf . get ( "wordFile" )+ "]" );
}
this . collector = collector ;
}
In this method we also create the reader, which is responsible for reading the files. Next
we need to implement public void nextTuple() , from which we'll emit values to be
processed by the bolts. In our example, the method will read the file and emit a value
per line.
public void nextTuple () {
if ( completed ){
try {
Thread . sleep ( 1 );
} catch ( InterruptedException e ) {