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Tomcat not loading its jars to classpath at run time

ramya narayanan

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posted 14 years ago

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Dear All,
I'm using Tomcat 5.5.27 version & this is my configuration of environment variables.

I've read that

Tomcat automatically appends the location of its jar files to your existing CLASSPATH.

Then I created a simple webapplication with the following directory structure:

My java source is in src/WebTest.java

when I compile it :

E:\apache-tomcat-5.5.27\webapps\FirstApplication\WEB-INF\src>javac WebTest.java
WebTest.java:4: package javax.servlet does not exist
import javax.servlet.ServletException;
                     ^
WebTest.java:5: package javax.servlet.http does not exist
import javax.servlet.http.HttpServlet;
                          ^
WebTest.java:6: package javax.servlet.http does not exist
import javax.servlet.http.HttpServletRequest;
                          ^
WebTest.java:7: package javax.servlet.http does not exist
import javax.servlet.http.HttpServletResponse;
                          ^
WebTest.java:9: cannot find symbol
symbol: class HttpServlet
public final class WebTest extends HttpServlet {
                                   ^
WebTest.java:11: cannot find symbol
symbol  : class HttpServletRequest
location: class WebTest
  public void doGet(HttpServletRequest request, HttpServletResponse response)
                    ^
WebTest.java:11: cannot find symbol
symbol  : class HttpServletResponse
location: class WebTest
  public void doGet(HttpServletRequest request, HttpServletResponse response)
                                                ^
WebTest.java:12: cannot find symbol
symbol  : class ServletException
location: class WebTest
    throws IOException, ServletException
                        ^
8 errors

1)It clearly meant that Tomcat has not loaded its jar servlet-api.jar into the classpath & why is it happening & what can be done to rectify this

2) Since I've ant I want to use Ant to separate source from the generated class files.
How to use that.
If i have the package structure com.common.java;
then the class files should be in webinf/classes/com/common/java/WebTest.class
How this can be achieved using Ant.
Remember ant is in my path.

BestRegards

Seetharaman Venkatasamy

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posted 14 years ago

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where you placed your servlet-api.jar . better to place in tomcat/common/lib

ramya narayanan

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The server was started using startup.bat
This is the document trace which i got when I run the server
I ran the server by

Server trace:

Dec 23, 2008 3:00:39 PM org.apache.catalina.core.AprLifecycleListener lifecycleE
vent
INFO: The Apache Tomcat Native library which allows optimal performance in produ
ction environments was not found on the java.library.path: C:\jdk1.5.0\bin;.;C:\
WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\W
bem;C:\Program Files\ZipGenius 6\;C:\jdk1.5.0\bin;c:\sai;C:\ant16\bin;E:\TestAnt
;
Dec 23, 2008 3:00:39 PM org.apache.coyote.http11.Http11BaseProtocol init
INFO: Initializing Coyote HTTP/1.1 on http-8080
Dec 23, 2008 3:00:39 PM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 828 ms
Dec 23, 2008 3:00:40 PM org.apache.catalina.core.StandardService start
INFO: Starting service Catalina
Dec 23, 2008 3:00:40 PM org.apache.catalina.core.StandardEngine start
INFO: Starting Servlet Engine: Apache Tomcat/5.5.27
Dec 23, 2008 3:00:40 PM org.apache.catalina.core.StandardHost start
INFO: XML validation disabled
Dec 23, 2008 3:00:41 PM org.apache.coyote.http11.Http11BaseProtocol start
INFO: Starting Coyote HTTP/1.1 on http-8080
Dec 23, 2008 3:00:41 PM org.apache.jk.common.ChannelSocket init
INFO: JK: ajp13 listening on /0.0.0.0:8009
Dec 23, 2008 3:00:41 PM org.apache.jk.server.JkMain start
INFO: Jk running ID=0 time=0/110  config=null
Dec 23, 2008 3:00:41 PM org.apache.catalina.storeconfig.StoreLoader load
INFO: Find registry server-registry.xml at classpath resource
Dec 23, 2008 3:00:41 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 2000 ms

Now when i compile, by appending the jar manually to the classpath it's working.

1)Why we should manually append the jar to the classpath doesn't Tomcat does it of its own

2) How to use Ant here to separate java from class files.
Regards.

ramya narayanan

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posted 14 years ago

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Dear seetharaman venkatasamy,
My servlet-api.jar is only in CATALINA_HOME\common\lib.
Where CATALINA_HOME is pointing to E:\apache-tomcat-5.5.27
Regards.

Vijitha Kumara

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1)It clearly meant that Tomcat has not loaded its jar servlet-api.jar into the classpath & why is it happening

Because here you are compiling the source files which has nothing to do with the tomcat (It's JAVA compiler you are using

). By the way it's really a bad practice to put the source files & compiling from inside the Application server.

Keep your development environment out of application server. When you want to deploy you may create a WAR or move the necessary files to the application server.

If i have the package structure com.common.java;
then the class files should be in webinf/classes/com/common/java/WebTest.class
How this can be achieved using Ant.

You have to use Ant's javac Task with srcdir and destdir attributes. Have a look at the manual for complete information.

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ramya narayanan

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After the class gets compiled , i enhanced the web.xml .
This is my web.xml

My class file is in classes folder.
1)Then I created a war file using

2) Copied these war file in webapps folder

3) Then I shutdown the server & restarted the server.

4) When I try to run

It says an error

HTTP Status 404 - /FirstApplication/

--------------------------------------------------------------------------------

type Status report

message /FirstApplication/

description The requested resource (/FirstApplication/) is not available.

--------------------------------------------------------------------------------

Apache Tomcat/5.5.27

How this can be fixed.
Is my web.xml proper.
I'm using tomcat version 5.5.27
Regards.

Ulf Dittmer

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posted 14 years ago

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What about http://localhost:8080/FirstApplication/start-web-test since that's the only resource you have mapped?

Does the Tomcat Manager (usually at http://localhost:8080/manager/html/list) list the application as running?
[ December 23, 2008: Message edited by: Ulf Dittmer ]

ramya narayanan

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What about http://localhost:8080/FirstApplication/start-web-test since that's the only resource you have mapped?

Correct ! Now when I go over the above link it's working & I get the output

A Simple Web Application
Here's some text...
...and a bit more text

But,

Does the Tomcat Manager (usually at http://localhost:8080/manager/html/list) list the application as running?

No.
The error it's showing is:

HTTP Status 403 - Access to the requested resource has been denied

--------------------------------------------------------------------------------

type Status report

message Access to the requested resource has been denied

description Access to the specified resource (Access to the requested resource has been denied) has been forbidden.

--------------------------------------------------------------------------------

Apache Tomcat/5.5.27

Thanks Ulf Dittmer for your valuable input.

For vijitha,

By the way it's really a bad practice to put the source files & compiling from inside the Application server.

I'm very eager to know why is it so? Because inside the application, i'm separating the source & class files right.

Because here you are compiling the source files which has nothing to do with the tomcat (It's JAVA compiler you are using )

But i'm using some dependencies ( some classes of servlet-api.jar) in my source file(WebTest.java) which directly access the tomcat dependencies only right.

You have to use Ant's javac Task with srcdir and destdir attributes. Have a look at the manual for complete information.

Certainly & thanks for the links.
Regards.

ramya narayanan

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posted 14 years ago

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Doesn't Tomcat load all of its jars inside common\lib to classpath when we start the server .
I have JAVA_HOME & also CATALINA_HOME defined properly, which is echoed when the server is started up.(Please see my second post)
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Ulf Dittmer

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Doesn't Tomcat load all of its jars inside common\lib to classpath when we start the server.

Yes it does, but as was said above, Tomcat has nothing to do with the Java compiler. And compiling servlets has no dependency on Tomcat - rather it depends on the jar file that contains the Servlet API. Tomcat just happens to include this jar file, that's all.

ramya narayanan

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Understood !
When we are compiling, we are compiling with the java compiler javac, which as of such doesn't know about servlet-api.jar or any other jars, which has to be directed using javac -classpath.
Then what is the use of Tomcat loading all the jars at the time of starting the server?
Regards.

Ulf Dittmer

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posted 14 years ago

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How could Tomcat function if it didn't have the servlet API and all those other jar files?

ramya narayanan

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For what function does Tomcat is loading these jars like servlet-api.jar & other jars in the classpath.
Regards.

ramya narayanan

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posted 14 years ago

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Any replies?

Ulf Dittmer

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Once again:

Originally posted by Ulf Dittmer:
How could Tomcat function if it didn't have the servlet API and all those other jar files available?

If you're curious what's inside of these jars, you can use "java -tf foobar.jar" to see all the classes. And if you're really curious how it all works, well, it's open source, so the source code is available for study.

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