Home » Eclipse Projects » Equinox » Running multiple instances of servletbridge in a tomcat instance
| Running multiple instances of servletbridge in a tomcat instance [message #119918] |
Tue, 21 October 2008 14:36  |
Eclipse User |
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Hi,
I'm having an issue with deploying two war files (say A and B) both of
which use servletbridge running under a single tomcat instance.
The scenario is this:
1. Visit JSF pages in A.
2. open up a JSF page in B. I get this error:
org.apache.jasper.JasperException: org.apache.jasper.JasperException: The
absolute uri: http://java.sun.com/jsf/core cannot be resolved in either
web.xml or the jar files deployed with this application
If I run only one of the web apps at a time, then it works fine. Also, If
I visit B first and then A, then I get the same error in A.
After debugging, I found out that bundles in A and B having the same ID
have problems. What happens is that when Tomcat tries to compile a jsp
page, it needs to access all the jar files in the webapp's classpath to
get all the tld declarations. Jasper uses JarURLConnection to get jar
files from bundles which gets cached by JarURLConnection. The URL looks
like, "bundleentry://<bundle_id>/web/WEB-INF/lib/jsf-impl.jar".
So, for the first web application that gets accessed, everything works
fine. Jar files are accessed correctly and downloaded, and tlds are read
properly. But when the second web application gets accessed, Tomcat tries
to access all the jar files in the classpath for the web app, and ends up
creating a URL that looks like
"bundleentry://<bundle_id>/web/WEB-INF/lib/jsf-impl.jar" , which looks
exactly the same as the URL in the first application.
Then, JarURLConnection decides to return the cached jar file for the
request. This fails because the cached jar file has already been deleted
by Tomcat. Therefore, the compilation of the jsp page fails. Besides,
the jar file is from a different web app anyways, so the logic seems wrong
to me.
FYI, the error itself is from
org.apache.jasper.compiler.TldLocationsCache#scanJar(JarURLC onnection,
boolean):364, but basically, JarURLConnection#getJarFile() is returning a
cached file that doesn't exist, which causes this problem.
Is this a bug, or by design?
Thanks,
taki
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| Re: Running multiple instances of servletbridge in a tomcat instance [message #119967 is a reply to message #119918] |
Tue, 21 October 2008 23:26  |
| Eclipse User |
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Servletbridge webapps are themselves isolated and in now way restricted from
running many instances in the same app server. I've run 30+ instances as
part of my testing. Can you describe how you've packaged your application.
Are you trying to use the app servers jsp and faces engine along with the
servletbridge? AFAIK this approach won't work.
If you're taking the suggested approach of embedding a JSF engine (like
myfaces) in your servlet bridge application you should be aware that there
were some as of yet unresolved modularity issues when running and embedding
a JSF engine in an OSGi environment. I recall the issue was in how
FactoryFinder shared resources but never dug into it myself. Perhaps you're
already aware of these problems?? (See a post by Mark Allerton -- August 16,
2007)
-Simon
"Takahiro Kato" <takahiro.kato@sap.com> wrote in message
news:65a61e7d455bf3907e5bc2e1e22ffde6$1@www.eclipse.org...
> Hi,
>
> I'm having an issue with deploying two war files (say A and B) both of
> which use servletbridge running under a single tomcat instance.
> The scenario is this:
> 1. Visit JSF pages in A.
> 2. open up a JSF page in B. I get this error:
> org.apache.jasper.JasperException: org.apache.jasper.JasperException: The
> absolute uri: http://java.sun.com/jsf/core cannot be resolved in either
> web.xml or the jar files deployed with this application
>
> If I run only one of the web apps at a time, then it works fine. Also, If
> I visit B first and then A, then I get the same error in A.
>
> After debugging, I found out that bundles in A and B having the same ID
> have problems. What happens is that when Tomcat tries to compile a jsp
> page, it needs to access all the jar files in the webapp's classpath to
> get all the tld declarations. Jasper uses JarURLConnection to get jar
> files from bundles which gets cached by JarURLConnection. The URL looks
> like, "bundleentry://<bundle_id>/web/WEB-INF/lib/jsf-impl.jar".
>
> So, for the first web application that gets accessed, everything works
> fine. Jar files are accessed correctly and downloaded, and tlds are read
> properly. But when the second web application gets accessed, Tomcat tries
> to access all the jar files in the classpath for the web app, and ends up
> creating a URL that looks like
> "bundleentry://<bundle_id>/web/WEB-INF/lib/jsf-impl.jar" , which looks
> exactly the same as the URL in the first application.
>
> Then, JarURLConnection decides to return the cached jar file for the
> request. This fails because the cached jar file has already been deleted
> by Tomcat. Therefore, the compilation of the jsp page fails. Besides,
> the jar file is from a different web app anyways, so the logic seems wrong
> to me.
>
> FYI, the error itself is from
> org.apache.jasper.compiler.TldLocationsCache#scanJar(JarURLC onnection,
> boolean):364, but basically, JarURLConnection#getJarFile() is returning a
> cached file that doesn't exist, which causes this problem.
>
>
> Is this a bug, or by design?
>
> Thanks,
>
> taki
>
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| Re: Running multiple instances of servletbridge in a tomcat instance [message #120017 is a reply to message #119967] |
Wed, 22 October 2008 18:54 |
| Eclipse User |
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Hi Simon,
Thanks for the reply.
Yes, I'm aware of the JSF issue, but I'm taking a different approach.
Basically, I'm taking multiple war files to deployed under two webapps
each of which uses servlet bridge. So, each of my webapp contains
multiple "used-to-be webapps" within it. The structure of a used-to-be
war file bundle looks like this:
web/
web/myjsp.jsp
...
web/WEB-INF
web/WEB-INF/lib
web/WEB-INF/lib/jsf-impl.jar
...
META-INF
META-INF/MANIFEST.MF
As you can see, I didn't create a separate bundle for JSF. JSF jars are
contained within each bundle that needs to use JSF. I have serveral
bundles that look like this within a war file, and i have two of those war
files.
Let's say I have war files A and B, and A contains bundle a, b, and c, and
B has d and e. all the bundles in A and B have the same structure as the
"war file bundle" as explained above. That means that each bundle
contains its own jsf-impl.jar file.
When A and B are deployed in a tomcat, OSGi starts up in both web apps,
and assign IDs to bundles. For example, in A, a will have an ID of 1, b
will have an ID of 2 etc. In B, d will have an ID of 1 as it's a totally
separate OSGi instance from that of A.
However, the interesting thing is that, when those bundles are read to get
tlds as I described in the original post, jsf-impl.jar, for example, are
considered the same by URLConnection object created by the jasper
compiler. It seems that it happens because the URL to jar files in a (in
A with ID of 1) and d (in B with ID of 1) look exactly the same. For
example, the URL to the jsf-impl.jar in a and d both would look like
"bundleentry://1/web/WEB-INF/lib/jsf-impl.jar.
This is a problem as the contents of jar files in different web apps can
be shared unintentionally. (in my case, though, the cached jar file
downloaded using URLConnection has been deleted by the time the second web
app tries to retrieve to use it -- hence the tld not found error)
IMHO, the keys to reproduce this issue are:
1. two "war file bundles" deployed under different webapps need to have
exactly the same structures so that the URL path to a jar file would look
exactly the same.
2. the war file bundles must contain the same jar files. again, this is
necessary as the URL path to it must look the same.
3. the war file bundles that satisfy above must have the same bundle ID.
Please let me know if I'm not clear.
thanks,
taki
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| Re: Running multiple instances of servletbridge in a tomcat instance [message #120043 is a reply to message #120017] |
Wed, 22 October 2008 21:35 |
| Eclipse User |
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Thanks Taki,
Would it be possible for you to open a bug and construct an example that I
could try on my machine. I think you do have something here.
I'm at a loss why the cached result of the URLConnection is being re-used
across frameworks. We use a special URLStreamHandlerFactory to figure out
which framework is the owner of a particular bundleentry (or any other type
of) URL. There could conceivably be a bug in there but off the top of my
head all I can think of is that somewhere in the URLClassLoader chain the
implementation is somehow doing some caching of the result. In particular
I'd be suspicious of how the jar URLHandler caches jar files loaded from
non-file URLConnections. You've identified that there might be an issue with
bundleentry URLs with the same external form but operating in different
framework instances. We might be able to make a change to guarantee
uniqueness cross framework in the same VM but we would need have a
legitimate testcase to justify this sort of a change.
-Simon
"Takahiro Kato" <takahiro.kato@sap.com> wrote in message
news:2f7a19b388725fbb2c5d97d3707351a2$1@www.eclipse.org...
> Hi Simon,
>
> Thanks for the reply.
>
> Yes, I'm aware of the JSF issue, but I'm taking a different approach.
>
> Basically, I'm taking multiple war files to deployed under two webapps
> each of which uses servlet bridge. So, each of my webapp contains
> multiple "used-to-be webapps" within it. The structure of a used-to-be
> war file bundle looks like this:
>
> web/
> web/myjsp.jsp
> ..
> web/WEB-INF
> web/WEB-INF/lib
> web/WEB-INF/lib/jsf-impl.jar
> ..
> META-INF
> META-INF/MANIFEST.MF
>
> As you can see, I didn't create a separate bundle for JSF. JSF jars are
> contained within each bundle that needs to use JSF. I have serveral
> bundles that look like this within a war file, and i have two of those war
> files.
>
> Let's say I have war files A and B, and A contains bundle a, b, and c, and
> B has d and e. all the bundles in A and B have the same structure as the
> "war file bundle" as explained above. That means that each bundle
> contains its own jsf-impl.jar file.
>
> When A and B are deployed in a tomcat, OSGi starts up in both web apps,
> and assign IDs to bundles. For example, in A, a will have an ID of 1, b
> will have an ID of 2 etc. In B, d will have an ID of 1 as it's a totally
> separate OSGi instance from that of A.
>
> However, the interesting thing is that, when those bundles are read to get
> tlds as I described in the original post, jsf-impl.jar, for example, are
> considered the same by URLConnection object created by the jasper
> compiler. It seems that it happens because the URL to jar files in a (in
> A with ID of 1) and d (in B with ID of 1) look exactly the same. For
> example, the URL to the jsf-impl.jar in a and d both would look like
> "bundleentry://1/web/WEB-INF/lib/jsf-impl.jar.
>
> This is a problem as the contents of jar files in different web apps can
> be shared unintentionally. (in my case, though, the cached jar file
> downloaded using URLConnection has been deleted by the time the second web
> app tries to retrieve to use it -- hence the tld not found error)
>
> IMHO, the keys to reproduce this issue are:
> 1. two "war file bundles" deployed under different webapps need to have
> exactly the same structures so that the URL path to a jar file would look
> exactly the same.
> 2. the war file bundles must contain the same jar files. again, this is
> necessary as the URL path to it must look the same.
>
> 3. the war file bundles that satisfy above must have the same bundle ID.
>
>
> Please let me know if I'm not clear.
>
>
> thanks,
>
> taki
>
>
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