我正在尝试编写一个执行以下操作的拓扑：
- 订阅 twitter 提要的 spout（基于关键字）
- 一个聚合螺栓，它聚合一个集合中的许多推文（比如 N）并将它们发送到打印机螺栓
- 一个简单的螺栓，可以立即将集合打印到控制台。
实际上，我想对集合进行更多处理。
我在本地对其进行了测试，看起来它正在工作。但是，我不确定我是否正确设置了螺栓上的分组，以及在实际风暴集群上部署时是否可以正常工作。如果有人可以帮助查看此拓扑并提出任何错误、更改或改进建议，我将不胜感激。
谢谢。
这就是我的拓扑结构。
builder.setSpout("spout", new TwitterFilterSpout("pittsburgh"));
builder.setBolt("sampleaggregate", new SampleAggregatorBolt())
.shuffleGrouping("spout");
builder.setBolt("printaggreator",new PrinterBolt()).shuffleGrouping("sampleaggregate");
聚合螺栓
public class SampleAggregatorBolt implements IRichBolt {
protected OutputCollector collector;
protected Tuple currentTuple;
protected Logger log;
/**
* Holds the messages in the bolt till you are ready to send them out
*/
protected List<Status> statusCache;
@Override
public void prepare(Map stormConf, TopologyContext context,
OutputCollector collector) {
this.collector = collector;
log = Logger.getLogger(getClass().getName());
statusCache = new ArrayList<Status>();
}
@Override
public void execute(Tuple tuple) {
currentTuple = tuple;
Status currentStatus = null;
try {
currentStatus = (Status) tuple.getValue(0);
} catch (ClassCastException e) {
}
if (currentStatus != null) {
//add it to the status cache
statusCache.add(currentStatus);
collector.ack(tuple);
//check the size of the status cache and pass it to the next stage if you have enough messages to emit
if (statusCache.size() > 10) {
collector.emit(new Values(statusCache));
}
}
}
@Override
public void cleanup() {
}
@Override
public void declareOutputFields(OutputFieldsDeclarer declarer) {
declarer.declare(new Fields("tweets"));
}
@Override
public Map<String, Object> getComponentConfiguration() {
return null; //To change body of implemented methods use File | Settings | File Templates.
}
protected void setupNonSerializableAttributes() {
}
}
打印机螺栓
public class PrinterBolt extends BaseBasicBolt {
@Override
public void execute(Tuple tuple, BasicOutputCollector collector) {
System.out.println(tuple.size() + " " + tuple);
}
@Override
public void declareOutputFields(OutputFieldsDeclarer ofd) {
}
}