Java NoClassDefFoundError : Apache Flink Complex Event Processing

Question

I am trying to understand the Apache Flink CEP program to monitor rack temperatures in a data center as described by Flink Official Documentation. But when I follow the steps and create a jar using mvn clean package and tried to execute the package using the command

java -cp "../cep-monitoring-1.0.jar" org.stsffap.cep.monitoring.CEPMonitoring

But I get the following error,

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/flink/streaming/api/functions/source/SourceFunction
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
    at java.lang.Class.privateGetMethodRecursive(Class.java:3048)
    at java.lang.Class.getMethod0(Class.java:3018)
    at java.lang.Class.getMethod(Class.java:1784)
    at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526)
Caused by: java.lang.ClassNotFoundException: org.apache.flink.streaming.api.functions.source.SourceFunction
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 7 more

I tried different variations of giving the classpath as described here but getting the same error. Can someone point out my mistake in running the program?

Yes. So the flink cluster should be executed explicitly in the background? — Ankit Jain, Feb 22 '18 at 13:57
You could include a piece of your pom.xml to better understand if you have the dependencies. — Alex, Feb 22 '18 at 14:25

score 2 · Answer 1 · answered Feb 22 '18 at 14:24

To submit a job to the local Flink cluster:

Run Flink.

/path/to/flink-1.4.0/bin/start-local.sh

Submit the job.

/path/to/flink-1.4.0/bin/flink run -c com.package.YourClass /path/to/jar.jar

Alternatively you can run the job simply from your IDE:

Your job in this case will be run in a Flink environement. Check Flink's example: https://github.com/apache/flink/blob/master/flink-examples/flink-examples-streaming/src/main/java/org/apache/flink/streaming/examples/wordcount/WordCount.java

score 1 · Accepted Answer · answered Feb 22 '18 at 20:38

The cep example uses flink version 1.3.2. So here are the steps to run it.

Install version 1.3.2 of apache flink. (wget it from here and extract it).
cd into flink-1.3.2
./bin/start-local.sh, this will start the flink cluster. Do cd ...
Clone this repo using git clone and cd into that.
mvn clean package to build the project. This will create target directory.
Run ../flink-1.3.2/bin/flink run target/cep-monitoring-1.0.jar, to start the process.
In separate terminal the output can be logged like this (assuming that you are in same directory as previous step) tail -f ../flink-1.3.2/log/flink-*-jobmanager-*.out (* will be replaced by specific user detail, press tab to autocomplete those).

Here is the sample output,

rshah9@bn18-20:~/tools/cep-monitoring-master$ tail -f ../flink-1.3.2/log/flink-rshah9-jobmanager-0-bn18-20.dcs.mcnc.org.out
TemperatureWarning(9, 102.45860162626161)
TemperatureWarning(6, 113.21295716135027)
TemperatureWarning(5, 105.46064102697723)
TemperatureWarning(0, 106.44635415722034)
TemperatureWarning(4, 112.07396748089734)
TemperatureWarning(9, 114.53346561628322)
TemperatureWarning(3, 109.05305417712648)
TemperatureWarning(7, 112.3698094257147)
TemperatureWarning(3, 107.78609416982076)
TemperatureWarning(9, 107.34373990230458)
TemperatureWarning(5, 111.46480675461656)

Java NoClassDefFoundError : Apache Flink Complex Event Processing

2 Answers2