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Posted to users@felix.apache.org by Chetan Mehrotra <ch...@gmail.com> on 2012/09/02 17:00:50 UTC
Determining Servlet class which handles a given HTTP request
At times while debugging we need to find the servlet class name which
handles a particular request. In a JEE based Web Application one can find
out that by looking at the web.xml. However in OSGi it becomes bit tricky
to find out the information easily. Some information is provided by the
"Http Whiteboard" WebConsole Plugin [1]. However it does not provide
information about servlets which are registered directly through
org.osgi.service.http.HttpService.registerServlet(String, Servlet,
Dictionary, HttpContext) method or servlets which are managed by other Fwk
like Sling
In case of Felix HttpService implementation this information is present
with o.a.f.http.base.internal.handler.HandlerRegistry [2] so I had to use
Sling Script Console [3] with script [7] to extract that information. It
would useful if all this information is exposed as part of some WebConsole
plugin similar to "Http Whiteboard" plugin. I am not sure what would be the
best way to achieve that but if we have a WebConsole plugin which exposes
some sort of API to allow various sub systems to provide Servlet
registration info then it can be used to provide all the required
information at one place collected from various sources like
1. Http Whiteboard information
2. HttpService handlerRegistry (possibly a super set of #1)
3. SlingServletResolver [4]
4. Sling Filter Printer [5]
At minimum having access to HandlerRegistry state via current Http
Whiteboard would also help. Information related to Sling can somewhat be
extracted from Recent Requests plugin [6]
Thoughts?
Chetan Mehrotra
[1]
https://github.com/apache/felix/blob/trunk/http/whiteboard/src/main/java/org/apache/felix/http/whiteboard/internal/manager/HttpWhiteboardWebConsolePlugin.java
[2]
https://github.com/apache/felix/blob/trunk/http/base/src/main/java/org/apache/felix/http/base/internal/handler/HandlerRegistry.java
[3] https://github.com/chetanmeh/c/wiki/Sling-Script-Console
[4]
https://github.com/apache/sling/blob/trunk/bundles/servlets/resolver/src/main/java/org/apache/sling/servlets/resolver/internal/SlingServletResolver.java
[5]
https://github.com/apache/sling/blob/trunk/bundles/engine/src/main/java/org/apache/sling/engine/impl/WebConsoleConfigPrinter.java
[6] http://sling.apache.org/site/monitoring-requests.html
[7]
import org.osgi.service.http.HttpService
import org.osgi.framework.FrameworkUtil
import org.osgi.framework.Bundle
def httpService = sling.getService(HttpService.class)
httpService.handlerRegistry.aliasMap.each{alias,servlet ->
Bundle bnd = FrameworkUtil.getBundle(servlet.class)
println "$alias : ${servlet.class.name} ($bnd.symbolicName)"
}
Re: Determining Servlet class which handles a given HTTP request
Posted by Felix Meschberger <fm...@adobe.com>.
Hi,
Am 28.09.2012 um 13:53 schrieb Chetan Mehrotra:
>> (BTW: I had to change the formatting of the new class. Please, in the future, apply our formatting styles. See [1] . Thanks.)
>
> I had checked that link but there was no formatting file for Intellij.
> So in the end I took the liberty of getting you to perform the
> formatting :)
;-)
> Would try to configure my Intellij as per guideline for
> future work though
Yeah, we don't have one for IntelliJ ... if only we had ... (hint, hint ;-) )
Regards
Felix
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Re: Determining Servlet class which handles a given HTTP request
Posted by Chetan Mehrotra <ch...@gmail.com>.
> (BTW: I had to change the formatting of the new class. Please, in the future, apply our formatting styles. See [1] . Thanks.)
I had checked that link but there was no formatting file for Intellij.
So in the end I took the liberty of getting you to perform the
formatting :) Would try to configure my Intellij as per guideline for
future work though
Chetan Mehrotra
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Re: Determining Servlet class which handles a given HTTP request
Posted by Felix Meschberger <fm...@adobe.com>.
Hi Chetan
Thanks for providing the patch. I have applied it and resolved the issue. You might want to crosscheck, whether all still works...
(BTW: I had to change the formatting of the new class. Please, in the future, apply our formatting styles. See [1] . Thanks.)
Regards
Felix
[1] http://felix.apache.org/site/coding-standards.html
Am 26.09.2012 um 18:39 schrieb Chetan Mehrotra:
> Created issue FELIX-3684 [1] and provided patch which exposes a
> webconsole plugin. This plugin displays information in a manner
> similar to how HTTP Whiteboard plugin does
>
> Chetan Mehrotra
> [1] https://issues.apache.org/jira/browse/FELIX-3684
>
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Re: Determining Servlet class which handles a given HTTP request
Posted by Chetan Mehrotra <ch...@gmail.com>.
Created issue FELIX-3684 [1] and provided patch which exposes a
webconsole plugin. This plugin displays information in a manner
similar to how HTTP Whiteboard plugin does
Chetan Mehrotra
[1] https://issues.apache.org/jira/browse/FELIX-3684
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Re: Determining Servlet class which handles a given HTTP request
Posted by Felix Meschberger <fm...@adobe.com>.
Hi Chetan
Am 02.09.2012 um 10:11 schrieb Chetan Mehrotra:
>> I am not sure whether it is possible at all to have a single plugin suitable for all of the Http Service plus any existing frameworks ... This would rather be something pluggable...
>
> A - Would it make sense to implement a new plugin in Http base module.
> As the Http base module has access to all the internal state and which
> is also super set of information present with Http Whiteboard module.
> This plugin can dump all the information present in HandlerRegistry.
+1
>
> B - Further it can expose some API similar to ConfigurationPrinter say
> ServletConfigPrinter. This API can then be implemented by Sling
> servlet resolver module module which provide the information it has
> about various servlets it manages. The information might consist of
>
> 1. Servlet Alias
> 2. Servlet Class
> 3. Bundle which provides that servlet
>
> Similarly information about registered filters can be captured
The problem is that for Sling there is no "Servlet alias" and servlet selection for request exection is really special and a lot more elaborate than plain Servlet API.
We (Sling) could of course fold the servlet registration paths (we use for Servlet Resource Registration) into a multi-value alias definition. But I am not sure, whether this helps, really.
Regards
Felix
>
> Chetan Mehrotra
>
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Re: Determining Servlet class which handles a given HTTP request
Posted by Chetan Mehrotra <ch...@gmail.com>.
> I am not sure whether it is possible at all to have a single plugin suitable for all of the Http Service plus any existing frameworks ... This would rather be something pluggable...
A - Would it make sense to implement a new plugin in Http base module.
As the Http base module has access to all the internal state and which
is also super set of information present with Http Whiteboard module.
This plugin can dump all the information present in HandlerRegistry.
B - Further it can expose some API similar to ConfigurationPrinter say
ServletConfigPrinter. This API can then be implemented by Sling
servlet resolver module module which provide the information it has
about various servlets it manages. The information might consist of
1. Servlet Alias
2. Servlet Class
3. Bundle which provides that servlet
Similarly information about registered filters can be captured
Chetan Mehrotra
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Re: Determining Servlet class which handles a given HTTP request
Posted by Felix Meschberger <fm...@adobe.com>.
Hi,
Am 02.09.2012 um 09:00 schrieb Chetan Mehrotra:
> At times while debugging we need to find the servlet class name which
> handles a particular request. In a JEE based Web Application one can find
> out that by looking at the web.xml. However in OSGi it becomes bit tricky
> to find out the information easily. Some information is provided by the
> "Http Whiteboard" WebConsole Plugin [1]. However it does not provide
> information about servlets which are registered directly through
> org.osgi.service.http.HttpService.registerServlet(String, Servlet,
> Dictionary, HttpContext) method or servlets which are managed by other Fwk
> like Sling
Right.
I created the "Http Whiteboard" plugin to see how and whether the whiteboard works. But maybe it is too short-sighted with respect to servlets and filters registered through the service. This is definitively something which should be improved.
As to registration through other frameworks, particularly Sling: This is not something that we in the Apache Felix project can do much about (except for those servlets and filters registered through the HttpService (or ExtHttpService). Particularly in the case of Sling the servlets are only registered inside of Sling and not with the Http Service, that is the Http Service does not know anything about them.
So I think these other frameworks should care to display that information and you should contact that community.
>
> In case of Felix HttpService implementation this information is present
> with o.a.f.http.base.internal.handler.HandlerRegistry [2] so I had to use
> Sling Script Console [3] with script [7] to extract that information. It
> would useful if all this information is exposed as part of some WebConsole
> plugin similar to "Http Whiteboard" plugin. I am not sure what would be the
> best way to achieve that but if we have a WebConsole plugin which exposes
> some sort of API to allow various sub systems to provide Servlet
> registration info then it can be used to provide all the required
> information at one place collected from various sources like
>
> 1. Http Whiteboard information
exists
> 2. HttpService handlerRegistry (possibly a super set of #1)
+1, as I said
> 3. SlingServletResolver [4]
Problem of Sling. But I have been thinking about a plugin for that one where you could enter an URL (or path) and the plugin would return the candidate scripts and servlets and mark the selected one.
> 4. Sling Filter Printer [5]
>
> At minimum having access to HandlerRegistry state via current Http
> Whiteboard would also help. Information related to Sling can somewhat be
> extracted from Recent Requests plugin [6]
>
> Thoughts?
I am not sure whether it is possible at all to have a single plugin suitable for all of the Http Service plus any existing frameworks ... This would rather be something pluggable...
Regards
Felix
>
> Chetan Mehrotra
>
> [1]
> https://github.com/apache/felix/blob/trunk/http/whiteboard/src/main/java/org/apache/felix/http/whiteboard/internal/manager/HttpWhiteboardWebConsolePlugin.java
>
> [2]
> https://github.com/apache/felix/blob/trunk/http/base/src/main/java/org/apache/felix/http/base/internal/handler/HandlerRegistry.java
>
> [3] https://github.com/chetanmeh/c/wiki/Sling-Script-Console
> [4]
> https://github.com/apache/sling/blob/trunk/bundles/servlets/resolver/src/main/java/org/apache/sling/servlets/resolver/internal/SlingServletResolver.java
>
> [5]
> https://github.com/apache/sling/blob/trunk/bundles/engine/src/main/java/org/apache/sling/engine/impl/WebConsoleConfigPrinter.java
> [6] http://sling.apache.org/site/monitoring-requests.html
>
> [7]
> import org.osgi.service.http.HttpService
> import org.osgi.framework.FrameworkUtil
> import org.osgi.framework.Bundle
>
> def httpService = sling.getService(HttpService.class)
> httpService.handlerRegistry.aliasMap.each{alias,servlet ->
> Bundle bnd = FrameworkUtil.getBundle(servlet.class)
> println "$alias : ${servlet.class.name} ($bnd.symbolicName)"
> }
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