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Setting classpath

Contents

What is classpath?

Packages, directories, zip files and jar files

Setting classpath for WebLogic Server

Important note regarding WebLogic RMI over IIOP

Java system classpath

WebLogic classpath

Setting the Java system classpath

Setting the Java system classpath in the environment

Setting the Java system classpath from the Java command line

What to put in your classpath

to start a WebLogic Server

Important note regarding WebLogic RMI over IIOP

To run a JDBC client

To run a JDBC driver with a WebLogic multitier driver

To run third-party applications with WebLogic Server

to run client applications

to run WebLogic Java utilities

to compile Java applications using WebLogic classes

to run WebLogic Server without dynamic classloading

Using variables to set classpath

Common problems and solutions

What is classpath?

Classpath is used by a Java application to locate the Java classes it needs to run. Classpath lists the directories, .jar

files, or .zip files that contain the compiled Java classes. Since these classes could be anywhere on your system or network, you need to specify where to find the classes you are trying to run. The contents of your classpath will vary depending on the system you are running and how your directories are organized. Classpath can be set either as an environment variable, or from the java command line.

Setting classpath correctly is essential for running any Java application. WebLogic Server has some very specific requirements for setting classpath, so care should be taken in setting classpath correctly. For additional information on setting classpath when compiling or running the examples shipped with WebLogic see Setting your development environment.

Packages, directories, .zip files and .jar files

Packages and directories

It can be tricky to figure out exactly what needs to be in your classpath. In order to understand what to put in your classpath, you need to understand a little about Java package names. Package names are well described by JavaSoft in the Java tutorial.

A package name reflects the directory structure of how the Java file is stored on disk. For example, the class weblogic.common.T3Client is located inside
(in UNIX)

  /weblogic/classes/weblogic/common/T3Client.class

(or in Windows NT)

  c:\weblogic\classes\weblogic\common\T3Client.class

The directory structure is reflected in the package name. The way we refer to this relationship is as follows: The directory that represents the "left-most" part of the package -- in this example, the "weblogic" of "weblogic.common.T3Client" -- should be contained in the directory (classes, in this case) that you list in your classpath.

That means for this particular package, you'd need to add the directory weblogic/classes to your classpath. If your own classes do not use package names, then you will include the directory or directories that contain your Java class files.

.jar and .zip files

Some products, like the JDK, are shipped with all of the Java classes zipped into a single .zip or .jar file. Other products, like WebLogic Server, are shipped with the classes unzipped. When the classes are in a .zip or .jar file, you need to include the .jar or .zip file itself in the classpath. Otherwise, the classpath just points to a directory.

Setting classpath for WebLogic Server

To start WebLogic Server, use a combination of two classpaths, the Java system classpath and the WebLogic classpath. This enables WebLogic Server to use Dynamic class loading, a process that allows you to deploy, redeploy, and undeploy Enterprise Java Beans and servlets in a running WebLogic Server without restarting WebLogic Server. (Note that you should NOT locate your EJBs in the weblogic.class.path.) For more information on the Hot Deploy feature, see Using WebLogic Server hot deploy.

Note that dynamic classloading works only with JavaSoft JDKs; it does not yet work with the Microsoft SDK for Java (Jview). You can run WebLogic Server without dynamic classloading, but you will need to set your classpath differently.

Important note regarding WebLogic RMI over IIOP

If you are using WebLogic RMI over IIOP, you must set your classpath differently than is described in this document. For details, see Using WebLogic RMI over IIOP.

Java system classpath

The Java system classpath can be set with the environment variable CLASSPATH or with the -classpath option from the java command line. The Java system classpath contains classes needed to start WebLogic Server.

WebLogic classpath

The WebLogic classpath, is set with the weblogic.class.path property on the java command line. The weblogic.class.path property specifies the location of classes that WebLogic Server needs to run.

Setting the Java system classpath

Setting the Java system classpath in the environment

Setting the Java system classpath in the environment as an environment variable is a common way to set your classpath. However, BEA recommends that you set your classpath on the java command line or in your scripts rather than setting your Java system classpath by setting the CLASSPATH environment variable.

Setting the Java system classpath using the -classpath option on the Java command line setting overrides any environment settings and therefore prevents extraneous classes from being loaded. Setting classpath in this manner also allows you to set different Java system classpaths for different applications, which is often necessary when developing and deploying applications using WebLogic Server. For convenience, you may wish to set up your own variables to substitute for commonly used classpaths.

If you decide to set the Java system classpath in your environment, you must put only those classes detailed in this document as belonging in the Java system classpath in your environment CLASSPATH variable. Instructions for setting the CLASSPATH environment variable vary among platforms and operating systems. Check the documentation for your platform or your JDK for details.

Setting the Java system classpath from the java command line

You can set your Java system classpath from the java command line with the -classpath option. This setting will override any classpath previously set in the environment. For example:

  $ java ... -classpath c:/java/lib/classes.zip;
    c:/weblogic/classes/boot;
    c:/weblogic/eval/cloudscape/lib/cloudscape.jar ...

Note that when you specify a Java system classpath in this manner it will only be in effect when executing the Java class on that command line. You will need to specify it again each time you run the java command.

What to include in your classpath

Depending on the Java application you are running, the classes you include in your classpath will vary. This section tells you how to set your classpath to start a WebLogic Server and to perform other common tasks. Since each task requires a different classpath -- one that can be laborious to type -- you may wish to set up variables to represent these various classpaths. See Using variables to set classpath for details.

To start a WebLogic Server

Specify the following classes in the Java system classpath:
- classes.zip file located in the java/lib directory of your Java installation. Omit this entry if you are running under Java 2 (JDK 1.2.x).
- weblogic/classes/boot
- weblogic/eval/cloudscape/lib/cloudscape.jar You may omit this if you will NOT be using the evaluation copy of the Cloudscape DBMS included with the WebLogic distribution.
Specify the following classes in the WebLogic classpath, using the weblogic.class.path property.
- weblogic/myserver/serverclasses

For example:

$ java -classpath c:/java/lib/classes.zip;
    c:/weblogic/classes/boot;
    c:/weblogic/eval/cloudscape/lib/cloudscape.jar
    -Dweblogic.class.path=c:/weblogic/classes;
    c:/weblogic/lib/weblogicaux.jar;
    c:/weblogic/license;
    c:/weblogic/myserver/serverclasses weblogic.Server

(Where weblogic is the path to your WebLogic Server installation and java is the path to your JDK.)

Important note regarding WebLogic RMI over IIOP

If you are using WebLogic RMI over IIOP, you must set your classpath differently than is described in this document. For details, see Using WebLogic RMI over IIOP.

To run a JDBC client

Add the classes for the JDBC driver to the Java system classpath. If you are using WebLogic jDriver for Oracle, the Type 2 JDBC driver supplied with WebLogic, the classes are located in the weblogic/classes directory. For WebLogic jDriver for Informix, the classes are located in weblogic/informix4/classes; for WebLogic jDriver for Microsoft SQL Server, the classes are located in weblogic/mssqlserver4/classes. For more information, see Setting your development environment.

To run a JDBC driver with a WebLogic multitier driver

If you are using either a WebLogic JDBC driver or a driver from a third party with one of the WebLogic multitier drivers (pool, jts, or t3), append the classes for the driver to the WebLogic classpath when you start WebLogic Server (with the weblogic.class.path property).

WebLogic Type 2 JDBC drivers: If you are using WebLogic jDriver for Oracle, the Type 2 JDBC driver supplied with WebLogic, the classes are located in the weblogic/classes directory and are always included in the classpath used to run WebLogic Server.
WebLogic jDriver for Informix: Append weblogic/informix4/classes to your WebLogic classpath (with the weblogic.class.path property).
WebLogic jDriver for Microsoft SQL Server: Append weblogic/mssqlserver4/classes to your WebLogic classpath (with the weblogic.class.path property).

The WebLogic classpath is specified using the weblogic.class.path property on the command line when starting WebLogic Server.

For more information, see Using WebLogic JDBC

To run third-party applications with WebLogic Server

Append the classes for any third-party applications to the WebLogic classpath. The WebLogic classpath is specified using the weblogic.class.path property on the command line when starting WebLogic Server.

To set a classpath for running WebLogic client applications

the classes.zip file located in the java/lib directory of your Java installation. Omit this entry if you are running under Java 2 (JDK 1.2.x).
weblogic/classes
weblogic/lib/weblogicaux.jar
weblogic/license
weblogic/myserver/clientclasses
paths for user-written or third-party Java classes
(Where weblogic is the path to your WebLogic Server installation.)

To run WebLogic java utilities

classes.zip file located in the java/lib directory of your Java installation. Omit this entry if you are running under Java 2 (JDK 1.2.x).
weblogic/classes
weblogic/lib/weblogicaux.jar
(Where weblogic is the path to your WebLogic Server installation.)

For example, to run a utility called utils.dbping:

$ java -classpath c:/java/lib/classes.zip;
    c:/weblogic/classes;
    c:/weblogic/lib/weblogicaux.jar utils.dbping

To compile Java applications with dependencies on WebLogic classes

Compiling Java applications requires that you set a Java system classpath to use when running the Java compiler (javac or sj). You must include any classes that are called in your code. If your code calls weblogic.Server, do not forget to include /weblogic/classes/boot in your Java system classpath.

For example,

 $ javac -classpath c:/java/lib/classes.zip;
   c:/weblogic/classes/boot;
   c:/weblogic/classes -d c:/myclasses myJavaCode.java

To start WebLogic Server without dynamic classloading

Jview users and other users with special circumstances must use a different Java system classpath to start WebLogic Server that does not use dynamic class loading. Note that a WebLogic Server started in this way will not be able to utilize the hot deploy feature.

To start a WebLogic Server without dynamic classloading:

Include the following classes in the Java system classpath, with the -classpath (JavaSoft JDK) or /cp (Jview) option on the command line:
- the classes.zip file located in the java/lib directory of your Java installation. Omit this entry if you are running under Java 2 (JDK 1.2.x).
- weblogic/classes/boot
- weblogic/eval/cloudscape/lib/cloudscape.jar (If you will be using the Cloudscape DBMS.)
- weblogic/classes
- weblogic/lib/weblogicaux.jar
- weblogic/license
- weblogic/myserver/serverclasses
Do not set the WebLogic classpath using the weblogic.class.path property on the java command line. The WebLogic classpath is only used when starting WebLogic Server with dynamic class loading.

For example:

$ java -ms32m -mx32m -classpath
  c:/java/lib/classes.zip;c:/weblogic/classes/boot;
  c:/weblogic/classes;
  c:/weblogic/license;
  c:/weblogic/lib/weblogicaux.jar
  c:/weblogic/myserver/serverclasses weblogic.Server

Using variables to set classpath

You may set up your own environment variables to help you set classpath for various uses. For instance, you may wish to set up variables for the WebLogic classpath and the Java system classpath to be used when:

running WebLogic Server
running Java utilities
running client code
running your own applications
compiling Java code

Consult the documentation for your operating system for information on how to define environment variables.

For example:

  set JAVA_CLASSPATH=c:/java/lib/classes.zip;
    c:/weblogic/classes/boot

sets the variable JAVA_CLASSPATH for classes belonging in the Java system classpath and

  set WL_CLASSPATH=c:/weblogic/license;
    c:/weblogic/classes;c:/weblogic/lib/weblogicaux.jar;

sets the variable WL_CLASSPATH for classes belonging in the WebLogic classpath.

You would then start WebLogic Server with this command:

$ java -ms32m -mx32m -classpath %JAVA_CLASSPATH% 
  -Dweblogic.class.path=%WL_CLASSPATH% weblogic.Server

Windows convenience programs

When you install WebLogic Server with the InstallShield on Windows NT, the InstallShield automatically creates Windows Registry entries which store information about classpath and the location of your WebLogic installation.

This information in the Registry is used when you run WebLogic Server from the Windows start menu, as a Windows NT service, or using the Windows convenience program, wlserver.exe. This information is not used by any other program.

You may prepend a classpath to Java system classpath used by the Windows convenience programs with the wlconfig.exe -classpath command. You must run wlconfig.exe from the weblogic/bin directory, or add that directory to your system PATH. For example:

 $ wlconfig.exe -classpath c:/myclasses

The InstallShield creates an entry for the weblogic.class.path property in the Registry. You may override this setting with the following command:

 $ wlconfig.exe -Dweblogic.class.path=c:/newPaths

Note: If you change the Registry setting for weblogic.class.path, you will completely overwrite the value in the Registry with the new value you specify with wlconfig. For more information on wlconfig, including setting other parameters, see Using wlconfig.

Common problems and solutions

Many problems, especially when you are getting started, can be traced back to an incorrectly set classpath.

The best way to avoid problems is to keep your classpath as simple as possible. Signs that you may have a classpath problem include:

Java says "Can't find class ..." when you try to run a program.
You get one of these messages when you compile your code:
Package weblogic.common not found in import
or
Class weblogic.common.T3Client not found in type declaration
You get a java.lang.NoClassDefFoundError when you run a Java program.
You get a java.lang.ClassNotFoundException when you run a Java program. (The typical cause of this exception, as opposed to the NoClassDefFoundError, is that the code does a Class.forName() on a class that can't be found.)

Other, subtler classpath problems can show up in unexpected guises. For example, if you get a message like "Unable to initialize threads" when you try to run a Java program, it probably means that you have the JDK 1.0.2 classes in your classpath. WebLogic isn't supported for use with JDK 1.0.2. Your classpath should always point to the JDK 1.1 or JDK 1.2 classes.

For more information on classpath, check out JavaSoft's information on classpath and their Java Tutorial.