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Communication response from servlet fails but it worked before

gretty Gretscki

Joined: Feb 19, 2011
Posts: 1

I have an applet (where the user logins) & on pressing login button I send the login details to my servlet. In my applet, the function responsible for sending the login details to the servelt & receiving the servlet response object FAILS.

My problem is: I dont know why my function sendObject( Object o ) fails & I dont know how to fix it. Could you help me understand what is wrong & why?

I am using Apache 7.0. I think that receiving the response (getting the input stream) from the servlet fails but I dont know why & logging in was working fine the other day so I know my WEB-INF folder is set up fine & the web.xml is fine.

My function (I document where the function fails):

Java Console Output:
Result from applet.getCodeBase() = http://localhost:8080/Updater/
In sendObject(): Server returned HTTP response code: 500 for URL: http://localhost:8080/Updater/Updater

From the Apache log:
20/02/2011 11:15:08 AM org.apache.catalina.core.ApplicationContext log
INFO: ContextListener: contextInitialized()
20/02/2011 11:15:08 AM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener: contextInitialized()
20/02/2011 11:15:23 AM org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet Updater as unavailable
20/02/2011 11:15:23 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Allocate exception for servlet Updater
at javax.servlet.GenericServlet.getServletContext(
at UpdaterServlet.<init>( // REFER BELOW TO SEE LINE 32 OF THIS FILE
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(
at org.apache.catalina.core.StandardWrapper.loadServlet(
at org.apache.catalina.core.StandardWrapper.allocate(
at org.apache.catalina.core.StandardWrapperValve.invoke(
at org.apache.catalina.core.StandardContextValve.invoke(
at org.apache.catalina.core.StandardHostValve.invoke(
at org.apache.catalina.valves.ErrorReportValve.invoke(
at org.apache.catalina.valves.AccessLogValve.invoke(
at org.apache.catalina.core.StandardEngineValve.invoke(
at org.apache.catalina.connector.CoyoteAdapter.service(
at org.apache.coyote.http11.Http11Processor.process(
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$ Source)
at Source)

localhost_access_log...: - - [20/Feb/2011:11:15:12 +1100] "GET /Updater/index.html HTTP/1.1" 304 - - - [20/Feb/2011:11:15:15 +1100] "GET /Updater/UpdaterApplet.class HTTP/1.1" 304 - - - [20/Feb/2011:11:15:15 +1100] "GET /Updater/ContentTree.class HTTP/1.1" 304 - - - [20/Feb/2011:11:15:15 +1100] "GET /Updater/ContentMap.class HTTP/1.1" 304 - - - [20/Feb/2011:11:15:15 +1100] "GET /Updater/UpdaterApplet$1.class HTTP/1.1" 304 - - - [20/Feb/2011:11:15:15 +1100] "GET /Updater/SQLInterface.class HTTP/1.1" 304 - - - [20/Feb/2011:11:15:23 +1100] "GET /Updater/ObjSerializationInterface.class HTTP/1.1" 304 - - - [20/Feb/2011:11:15:23 +1100] "POST /Updater/Updater HTTP/1.1" 500 3117

This is the file (if you see above theres an error at line 32 of this file):

William Brogden
Author and all-around good cowpoke

Joined: Mar 22, 2000
Posts: 12868
You better go back and study the servlet life cycle. Apparently you are relying on the constructor for UpdaterServlet to do all the work. I suspect your init method for that servlet does not correctly set the servlet context which is why you get:

at javax.servlet.GenericServlet.getServletContext(

I agree. Here's the link:
subject: Communication response from servlet fails but it worked before