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Servlet not being called

 
chelakkad ben
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Hello,
Can someone pl tell me why this servlet is not being called?


"Hello world " Servlet
----------------------


Deployment Descriptor
---------------------

testservlet folder in webapps/

testservlet.class is in webapps/testservlet/WEB-INF/classes

index.html is in webapps/testservlet/ folder

The deployment descriptor web.xml is in folder webapps/testservlet/WEB-INF/

index.html
----------

Now when i click on the 'Execute ' link on this page
http://www.knobe.org:8080/testservlet/
i get the error

HTTP - 500
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Class testservlet is not a Servlet
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
java.lang.Thread.run(Unknown Source)


root cause

java.lang.ClassCastException: testservlet
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
java.lang.Thread.run(Unknown Source)

Subsequent requests generates the error..

HTTP Status 404 - Servlet testservlet is not available

type Status report

message Servlet testservlet is not available

description The requested resource (Servlet testservlet is not available) is not available.



At the same time the servlets-examples are working fine..ie if i click on the 'Execute' link on this index page, the example works.

http://www.knobe.org:8080/servlets-examples/

rgds
ben

[ December 16, 2006: Message edited by: chelakkad ben ]
[BSouther: Added UBB Code Tags]
[ December 16, 2006: Message edited by: Ben Souther ]
 
Ben Souther
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javax.servlet.ServletException: Class testservlet is not a Servlet



Try re-compiling your class and try again.
Restart your container as well.
Maybe the class file got corrupted.

Java API J2EE API Servlet Spec JSP Spec How to ask a question... Simple Servlet Examples jsonf

 
chelakkad ben
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Hello Ben,

Deleted the old class file, recompiled and restarted Tomcat. But still the same error is displayed...

HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.

exception
javax.servlet.ServletException: Class testservlet is not a Servlet
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
java.lang.Thread.run(Unknown Source)


root cause

java.lang.ClassCastException: testservlet
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool

Is there any prob with the configuration, i wonder?
rgds
csb
 
Rahul Bhattacharjee
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Try with this.



And try with this URL

Rahul Bhattacharjee
LinkedIn - Blog

 
chelakkad ben
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Hello Rahul,
Now what is 'myApp'?
you mean <a href="testservlet/testservlet">Execute</a> or what?
i dont get it. pl clarify.
rgds
 
Rahul Bhattacharjee
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I wanted you to use
<url-pattern>/myApp/testservlet</url-pattern>
in place of
<url-pattern>/servlet/testservlet</url-pattern>

and change the anchor tag also to request /myApp/testservlet URL
instead of /servlet/testservlet

What I guess is , there is something called invoker servler in tomcat which has a pattern similar to what you have used ?(/servler/fullclassname).

I am guessing that you are using tomcat and you have not enabled the invoker servlet in the web.xml file.
Well there should not be a problem , but still I think you should try this , may be this helps.

Rahul Bhattacharjee
LinkedIn - Blog

 
chelakkad ben
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Rahul,
I tried what you said. Changed to 'myApp' in web.xml and index.html.
but getting the same HTTP - 500 error
rgds
 
Prabhu Venkatachalam
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java.lang.ClassCastException: testservlet



It seems like, the class container took for servicing request is not a class which implements HttpServlet.

Try packing your class and change <servlet-class>.

Prabhu Venkatachalam<br />SCJP 1.4,SCWCD 1.4<br />prabhu.venkatachalam@gmail.com

 
chelakkad ben
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Hi Prabhu,
No need. The servlets-examples is working perfectly! Its /servlet/.. there.
ie. http://www.knobe.org:8080/servlets-examples/servlet/HelloWorldExample
works fine.
rgds
 
chelakkad ben
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Hello
Any one got the solution?
 
Ulf Dittmer
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Any URL that starts with "/servlet/" uses the invoker servlet mechanism, which works, but should not be used for reasons explained in that FAQ page.

Go with Rahuls suggestion of using URLs that include the name of your web app instead (myApp in his example), and double-check the mapping in web.xml.
 
chelakkad ben
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Hello Dittmer,

In that case why is www.knobe.org:8080/servlets-examples working?

My app name is testservlet. This folder is in webapps. So the mapping in web.xml should be...

<web-app>
<servlet>
<servlet-name>testservlet</servlet-name>
<servlet-class>testservlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>testservlet</servlet-name>
<url-pattern>/testservlet/testservlet</url-pattern>
</servlet-mapping>
</web-app>

Is that correct? The second 'testservlet' in the url-pattern being the class file. And the index.html in webapps/testservlet/ should have
<a href="testservlet/testservlet">Execute</a> . Right?

rgds
 
Ben Souther
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Originally posted by chelakkad ben:
Hello Dittmer,

In that case why is www.knobe.org:8080/servlets-examples working?

My app name is testservlet. This folder is in webapps. So the mapping in web.xml should be...

<web-app>
<servlet>
<servlet-name>testservlet</servlet-name>
<servlet-class>testservlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>testservlet</servlet-name>
<url-pattern>/testservlet/testservlet</url-pattern>
</servlet-mapping>
</web-app>

Is that correct? The second 'testservlet' in the url-pattern being the class file. And the index.html in webapps/testservlet/ should have
<a href="testservlet/testservlet">Execute</a> . Right?

rgds



At a glance that all looks right.
Is it still not working?

Java API J2EE API Servlet Spec JSP Spec How to ask a question... Simple Servlet Examples jsonf

 
Ulf Dittmer
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And the index.html in webapps/testservlet/ should have
<a href="testservlet/testservlet">Execute</a> . Right?



This looks wrong. If index.html is in webapps/testservlet, then a URL of "testservlet/testservlet" would access "testservlet/testservlet/testservlet". Try either href="testservlet" or href="/testservlet/testservlet".
 
Ben Souther
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Originally posted by Ulf Dittmer:


This looks wrong. If index.html is in webapps/testservlet, then a URL of "testservlet/testservlet" would access "testservlet/testservlet/testservlet". Try either href="testservlet" or href="/testservlet/testservlet".



Look at the URL pattern:
<url-pattern>/testservlet/testservlet</url-pattern>

/testservlet/testservlet/testservlet is what is needed in this case.

Java API J2EE API Servlet Spec JSP Spec How to ask a question... Simple Servlet Examples jsonf

 
Bear Bibeault
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Calls into question whether naming everything testservlet is a good idea or not, no?

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chelakkad ben
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Hi
Its all a bit confusing!! I have changed the class name to Hello. So will this do?

<web-app>
<servlet>
<servlet-name>Hello</servlet-name>
<servlet-class>Hello</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>Hello</servlet-name>
<url-pattern>/testservlet/Hello</url-pattern>
</servlet-mapping>
</web-app>

and the index.html in webapps/testservlet/ folder
<a href="/testservlet/Hello">Execute</a> ?

rgds
 
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Why do you insist upon making it harder than it needs to be?

Just make it:

<url-pattern>/Hello</url-pattern>

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chelakkad ben
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Hello

'Why do you insist upon making it harder than it needs to be?'

Sorry. Not intentionally. New to servlets.
Wont repeat,once i learn them.

Changed to what you said...
<web-app>
<servlet>
<servlet-name>Hello</servlet-name>
<servlet-class>Hello</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Hello</servlet-name>
<url-pattern>/Hello</url-pattern>
</servlet-mapping>
</web-app>
and the index.html with
<a href="/testservlet/Hello">Execute</a>

But still the error remains
HTTP Status 500
exception
javax.servlet.ServletException: Class Hello is not a Servlet
Any changes needed in conf/web.xml?
rgds
 
Ben Souther
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Try one of my examples.
SimpleServlet is a basic "Hello, World" program like the one you're trying to deploy.
http://simple.souther.us

Just download the war file and drop it into your webapps directory.
See if that one runs properly.
If it does, then you know your server is OK,
You can then compare your code with the code in the example to see what might be different.

Java API J2EE API Servlet Spec JSP Spec How to ask a question... Simple Servlet Examples jsonf

 
yu wang
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java.lang.ClassCastException means that your class have some problem. The tomcat don't think it as a servlet. Maybe your class don't have the post method.
 
Rahul Bhattacharjee
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Originally posted by yu wang:
java.lang.ClassCastException means that your class have some problem. The tomcat don't think it as a servlet. Maybe your class don't have the post method.



There is no method in servlet named post and if you are talking about doPost method , then ,it inherits the default version of doPost method from HTTPServlet class.

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Shashi Kant
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Try this out




[BSouther: Added UBB CODE tags]
[ December 20, 2006: Message edited by: Ben Souther ]

If it's true that we are here to help others, then what exactly are the others here for?

 
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