Hi Detelin,
Thanks very much for the information.
Would it possible to enter a bug report for this? That way your history
and input is properly captured and the Gemini Web maintainers can track it.
https://bugs.eclipse.org/bugs/enter_bug.cgi?product=Gemini.Web
Thanks,
-Mike
On 03/04/2014 9:21 AM, [email protected] wrote:
Seems it is not as trivial as I initially thought. After doing the
proposed changes, the simple-war is redeployed successfully. I then
went ahead and tested this on a more complex WAB but got an exception
during servlet initialization which indicated that the
"osgi-bundlecontext" servlet context attribute is not available.
Researching this further, I found out that Tomcat would re-create the
ServletContext instance when reloading a web application. Gemini Web
however is not coded to expect that ServletContext will change. In
fact, it assumes that the web application lifecycle is bound entirely
to the corresponding bundle's lifecycle, so it does not assume that
the web application might be controlled from Tomcat at all.
This seems like a general design issue of Gemini Web and solving it
might require changing the its architecture. I would be interested to
know if this issue has already been discussed and whether you think it
makes sense to improve Gemini Web to handle this use case.
Regards,
Detelin
On Wed, Apr 2, 2014 at 3:57 PM, <[email protected]
<mailto:[email protected]>> wrote:
Hello Gemini Web devs,
We are using Gemini Web with Equinox and we had to update our
test setup recently to reload a web application, while Tomcat is
running. We ended up using Tomcat JMX for that, but it turned out
a NPE is thrown when the web application is re-started. The issue
is reproducible with any web application bundle. To reproduce it
with latest Gemini Web 2.2.2 and the "simple-war.war" web
application, follow these steps:
1. Install the war in Equinox:
osgi> install file:simple-war.war
2. Run jconsole JDK tool and connect to the Equinox process
3. Open the "//localhost/simple-war" node under
"Catalina/WebModule", navigate to the operations and execute "reload"
4. Observe the following exception appears in Equinox console:
org.apache.catalina.core.StandardContext reload
SEVERE: Exception starting Context with name [/simple-war]
org.apache.catalina.LifecycleException: Failed to start component
[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/simple-war]]
at
org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
at
org.apache.catalina.core.StandardContext.reload(StandardContext.java:3926)
...
Caused by: org.apache.catalina.LifecycleException: Failed to start
component
[org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappLoader@6638e53]
...
Caused by: java.lang.NullPointerException
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleClassPathURLExtractor.extractBundleClassPathURLs(BundleClassPathURLExtractor.java:37)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappClassLoader.addBundleClassPathURLs(BundleWebappClassLoader.java:101)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappClassLoader.<init>(BundleWebappClassLoader.java:77)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappLoader.createClassLoader(BundleWebappLoader.java:88)
at
org.eclipse.gemini.web.tomcat.internal.loading.BundleWebappLoader.startInternal(BundleWebappLoader.java:169)
I checked the sources and it seems that the
BundleWebappClassLoader nulls out the "bundle" and
"classLoaderCustomizer" fields upon stop:
http://git.eclipse.org/c/gemini.web/org.eclipse.gemini.web.gemini-web-container.git/tree/org.eclipse.gemini.web.tomcat/src/main/java/org/eclipse/gemini/web/tomcat/internal/loading/BundleWebappLoader.java#n212
These are initialized in the constructor and since a new
BundleWebappClassLoader instance is not created when starting the
context after a stop, these remain null and ultimately cause the
exception.
It seems like the fix would be easy - removing the respective null
assigments so that the "bundle" and "classLoaderCustomizer"
instances are preserved. If there are no side effects and there is
no specific reason for this piece of code, I would open a defect
and attach a patch, but first I wanted to get your opinion on
this. Does this sound reasonable?
Thanks,
Detelin
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