Icepush add-on !

 I'm using Vaadin 7.6.2. 
 Now I add Icepush add-on ( 0.5.6 ) in my project. 
But when I run, it has error: "  java.lang.NoClassDefFoundError: org/vaadin/artur/icepush/ICEPush ". 
In folder Dependencies had icepush-0.5.6.jar .
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I rebuild my project had error :  "Failed to execute goal com.vaadin:vaadin-maven-plugin:7.6.2:compile (default) on project 'myProject': GWT Module org.icepush.gwt.ICEpush not found in project sources or resources."

How to fix ? 
Thanks all !
 

Thank @Tobias Demuth for your reply  !
I'm newbie. 
We use Server push as TimerTask for apply to initiate changes in the browser from the server ?

Especially as a newbie it will be much easier for you to just use the built-in support instead of an addon. Please follow the link to the documentation in my last post. 

OK - Thank you so much !