Hi,
I've submitted a question on stackoverflow regarding the serialization of
members of bolts.
I wanted to bring it to the attention of the subscribers of this list:
http://stackoverflow.com/questions/26931220/how-to-simply-set-up-a-serializer-for-storm-bolt-spout-members
Thanks.
PS: here's a copy of the question:
I have a bolt that uses a factory interface to create the tools it uses. It
creates those tools when `prepare` is called. The Factory implementation
only has basic members (strings, integers) that should be serializable by
default.
When I run my topology I get a `NotSerializableException`, coming from the
factory implementation. I was wondering how I could register a serializer
for the factory.
here's an example:
public class Demo extends BaseRichBolt {
public static interface IExecutor
{
public void execute( Tuple tuple );
}
public static interface IExecutorCreator
{
public IExecutor create( Map map, TopologyContext tc,
OutputCollector oc );
};
public static class DummyExecutor implements IExecutor
{
public void execute( Tuple tuple ) {}
};
public static class DummyExecutorCreator implements IExecutorCreator
{
String name_;
public DummyExecutorCreator(String name) { this.name_ = name;}
public IExecutor create(Map map, TopologyContext tc,
OutputCollector oc) {
return new DummyExecutor();
}
};
public void declareOutputFields(OutputFieldsDeclarer ofd) {
}
private IExecutor executor_;
private IExecutorCreator creator_;
public Demo(IExecutorCreator creator)
{
this.creator_ = creator;
}
public void prepare(Map map, TopologyContext tc, OutputCollector
oc) {
this.executor_ = this.creator_.create(map, tc, oc);
}
public void execute(Tuple tuple) {
this.executor_.execute(tuple);
}
}
And I get this error when I try to run it in a topology:
`java.io.NotSerializableException: Demo$DummyExecutorCreator`
As a side note I'm starting to wonder, why don't Storm have you to register
factories instead of Bolts and Spouts. since in the end they get serialized
and copied across the different threads, it'd be probably better to just
give storm a mean to generate those bolts and separate the concerns.
