Sunday, July 8, 2018

Re: After upgrading to GWT 2.8.2: Exception "ServiceConfigurationError: org.apache.juli.logging.Log: Provider org.eclipse.jetty.apache.jsp.JuliLog not a subtype" during Super Dev Mode

Hello Thomas,

sorry for my slow response, work schedule was a bit full the last days...

Eventually I could solve my problems and get it up running again - I really appreciate your help Thomas, thank you!

Am Montag, 2. Juli 2018 16:26:12 UTC+2 schrieb Thomas Broyer:

Just to clarify: by "in the logs", I specifically meant the "Jetty" tab in the DevMode window.
Oh I see. I checked it, there was no log message of the kind you mentioned.

Given what you shared about your classpath and WEB-INF/lib (where both classes only exist in gwt-dev.jar), I'm ready to bet that this is a classloader issue, where at one point the gwt-dev.jar is added to the webapp classloader (almost as if it was in the WEB-INF/lib), and then there are "conflicts" between the same class from the system classloader (DevMode) and the webapp classloader (WEB-INF/lib) can't be cast from/to one another.

Thanks for the explanation, that might be the problem. I was not able to check that, but fortunately, I could solve the problem by using a separate webserver, as you suggested.

When you start the CodeServer with -launcherDir, it writes a special myapp.nocache.js that automatically calls the CodeServer to (re)compile the application and then load the compiled app.

When it starts, the CodeServer starts a server (HTTP, port 9876 by default) and writes the a myapp/myapp.nocache.js in the -launcherDir, that references the CodeServer's URL (when you launch the DevMode, it actually launches the CodeServer behind the scene, with the -launcherDir being the same as the -war).
When your browser loads that myapp.nocache.js (through the web server that serves your webapp), it automatically "calls" the CodeServer to compile the app and then load it; this is what the bookmarklets did prior to GWT 2.7 (and can still do, if you don't use -launcherDir).

It is really helpful that you took the time to describe the process, now I understand it way better.

I ended up using the Eclipse Jetty Plugin to start my webapp and I created an Ant task to start the CodeServer like this:

<java failonerror="true" fork="true" classname="">
<path refid="gwtCodeServerClasspath" />

<jvmarg value="-Xmx1200m" />

<arg value="-launcherDir" />
<arg value="war" />
<arg value="-logLevel" />
<arg value="INFO" />
<arg value="-port" />
<arg value="9876" />
<arg value="de.myapp.MyWebApp" />

This setup works for me.

Just out of curiosity: Is there a difference between launching the DevMode with "-noserver" and CodeServer with "-launchDir"?

Thomas, thanks again for taking the time to help!

Kind regards

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