1. start/stop cluster: ./bin/start-cluster.sh ./bin/stop-cluster.sh

2. run default example: $ ./bin/flink run examples/streaming/WordCount.jar $ tail log/flink--taskexecutor-.out refer to https://ci.apache.org/projects/flink/flink-docs-release-1.12/try-flink/local_installation.html

3. prepare example:

• create maven based project
• write source code
• package jar file
• use ./bin/flink to invoke above jar file

• ./bin/flink run /tmp/wordcount-0.1.jar (consume default text)
• ./bin/flink run /tmp/wordcount-0.1.jar --input /opt/flink-1.12.1/README.txt --output /opt/flink-1.12.1/result.txt

• open one terminal, start local nc: nc -lk 9999
• open another terminal, invoke datastream example: ./bin/flink run /tmp/windowwordcount-0.1.jar
• back to first terminal, input value and enter to new line, continue to input
• open third terminal, check result under /opt/flink-1.12.1/log

input: root@hall-OptiPlex-9020:~# nc -lk 9999 aa aa aa aa aa aa aa aa aa aaa aaa aa aa aa bb bb bb bb bb bb bb bb bbb abc abc abc abc ded

output under third terminal: cat flink-root-taskexecutor-2-hall-OptiPlex-9020.out WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by org.apache.flink.shaded.akka.org.jboss.netty.util.internal.ByteBufferUtil (file:/opt/flink-1.12.1/lib/flink-dist_2.12-1.12.1.jar) to method java.nio.DirectByteBuffer.cleaner() WARNING: Please consider reporting this to the maintainers of org.apache.flink.shaded.akka.org.jboss.netty.util.internal.ByteBufferUtil WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release (aa,7) (aa,2) (aaa,2) (aa,3) (bb,5) (bb,3) (bbb,1) (abc,4) (ded,1)

output under second terminal: ./bin/flink run /tmp/windowwordcount-0.1.jar WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/opt/flink-1.12.1/lib/flink-dist_2.12-1.12.1.jar) to field java.lang.String.value WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release

View job status on GUI:

• http://10.182.173.198:8081/#/job/running

under second terminal, click "Ctrl + C" to quit stream process then get below output: ./bin/flink run /tmp/windowwordcount-0.1.jar WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/opt/flink-1.12.1/lib/flink-dist_2.12-1.12.1.jar) to field java.lang.String.value WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release Job has been submitted with JobID 4b78a3668e35c432a9258f8d8ce3efc7 Program execution finished Job with JobID 4b78a3668e35c432a9258f8d8ce3efc7 has finished. Job Runtime: 179893 ms

View job status on GUI:

• http://10.182.173.198:8081/#/job/completed

https://ci.apache.org/projects/flink/flink-docs-stable/learn-flink/