Please read the Basic API concepts guide in the documentation, in
particular
https://ci.apache.org/projects/flink/flink-docs-release-1.4/dev/api_concepts.html#lazy-evaluation.
The short answer is that main() is called on the client, while the sink
is executed on a taskmanager, i.e. in a different JVM. The sink must be
thus self-contained, i.e. it must call connectToMqttServer().
On 18.09.2017 06:00, Duy Truong wrote:
Hi
In my flink program, I want to send data to a server via MQTT
protocol, here is my code||
https://gist.github.com/duytruong/d240958d2c4140b554b604cbef05edc7
<https://gist.github.com/duytruong/d240958d2c4140b554b604cbef05edc7>
The problem is it ran well on IntelliJ, but when submitted to cluster
(bin/start-local.sh), it could connect but failed to send data. When
I've tried to move connectToMqttServer() to addSink(), it worked (on
cluster), so I have 2 questions:
1. Why it could connect but failed to send data, I guess the cause is
addSink() is executed in different thread from the
connectToMqttServer's thread but I can't find any document about it.
2. Why it ran well in IntelliJ but failed on cluster (I didn't move
connectToMqttServer() to addSink() in this case).
Thanks,
--
/Duy Truong/
