Dictionary/tomcat/RELEASE-NOTES

                     Apache Tomcat Version @VERSION@
                            Release Notes


$Id: RELEASE-NOTES,v 1.1 2005/02/21 06:54:22 amontano Exp $


============================
KNOWN ISSUES IN THIS RELEASE:
============================

* Tomcat 5.0 and JNI Based Applications
* Tomcat 5.0 Standard APIs Available
* Tomcat 5.0 and XML Parsers
* Web application reloading and static fields in shared libraries
* JAVAC leaking memory
* Tomcat on Linux
* Enabling SSI and CGI Support
* Security manager URLs
* Symlinking static resources
* Enabling invoker servlet
* Viewing the Tomcat Change Log
* When all else fails


-------------------------------------
Tomcat 5.0 and JNI Based Applications:
-------------------------------------

Applications that require native libraries must ensure that the libraries have
been loaded prior to use.  Typically, this is done with a call like:

  static {
    System.loadLibrary("path-to-library-file");
  }

in some class.  However, the application must also ensure that the library is
not loaded more than once.  If the above code were placed in a class inside
the web application (i.e. under /WEB-INF/classes or /WEB-INF/lib), and the
application were reloaded, the loadLibrary() call would be attempted a second
time.

To avoid this problem, place classes that load native libraries outside of the
web application, and ensure that the loadLibrary() call is executed only once
during the lifetime of a particular JVM.


----------------------------------
Tomcat 5.0 Standard APIs Available:
----------------------------------

A standard installation of Tomcat 5 makes all of the following APIs available
for use by web applications (by placing them in "common/lib" or "shared/lib"):
* ant.jar (Apache Ant 1.6 or later)
* commons-collections*.jar (Commons Collections 2.1 or later)
* commons-dbcp.jar (Commons DBCP 1.1 or later)
* commons-el.jar (Commons Expression Language 1.0)
* commons-logging-api.jar (Commons Logging API 1.0.3 or later)
* commons-pool.jar (Commons Pool 1.1 or later)
* jasper-compiler.jar (Jasper 2 Compiler)
* jasper-runtime.jar (Jasper 2 Runtime)
* jsp-api.jar (JSP 2.0 API)
* commons-el.jar (JSP 2.0 Expression Language)
* naming-common.jar (JNDI Context implementation)
* naming-factory.jar (JNDI object factories for J2EE ENC support)
* naming-resources.jar (JNDI DirContext implementations)
* servlet-api.jar (Servlet 2.4 API)

You can make additional APIs available to all of your web applications by
putting unpacked classes into a "classes" directory (not created by default),
or by placing them in JAR files in the "lib" directory.

Tomcat 5.0 also makes Xerces 2 and the Commons Logging API (release 1.0.3)
available to web applications.

Please note that the JMX API is available to applications as well.  The jmx.jar
file used to be located in the common/lib directory, but was moved to the bin
directory as part of the Tomcat 5.0.20 release.  The jmx.jar is in Tomcat's
bootstrap classpath (included via the Class Path line in bootstrap.jar's manifest).


--------------------------
Tomcat 5.0 and XML Parsers:
--------------------------

As described above, Tomcat 5.0 makes an XML parser (and many other standard
APIs) available to web applications.  This parser is also used internally
to parse web.xml files and the server.xml configuration file.  If you wish,
you may replace the "xercesImpl.jar" file in "common/endorsed" with another
XML parser, as long as it is compatible with the JAXP 1.2 APIs.

Xerces 2.6.2 is included.


---------------------------------------------------------------
Web application reloading and static fields in shared libraries:
---------------------------------------------------------------

Some shared libraries (many are part of the JDK) keep references to objects
instantiated by the web application. To avoid class loading related problems
(ClassCastExceptions, messages indicating that the classloader
is stopped, etc.), the shared libraries state should be reinitialized.

Something which might help is to avoid putting classes which would be
referenced by a shared static field in the web application classloader,
and putting them in the shared classloader instead (JARs should be put in the
"lib" folder, and classes should be put in the "classes" folder).


--------------------
JAVAC leaking memory:
--------------------

The Java compiler leaks memory each time a class is compiled. Web applications
containing hundreds of JSP files may as a result trigger out of memory errors
once a significant number of pages have been accessed. The memory can only be
freed by stopping Tomcat and then restarting it.

The JSP command line compiler (JSPC) can also be used to precompile the JSPs.

Note: This issue has been fixed in Sun JDK 1.4.x.


---------------
Tomcat on Linux:
---------------

Virtual machine crashes can be experienced when using certain combinations of
kernel / glibc under Linux with Sun Hotspot 1.2 to 1.3. The crashes were
reported to occur mostly on startup. Sun JDK 1.4 does not exhibit the problems,
and neither does IBM JDK for Linux.

The problems can be fixed by reducing the default stack size. At bash shell,
do "ulimit -s 2048"; use "limit stacksize 2048" for tcsh.

GLIBC 2.2 / Linux 2.4 users should also define an environment variable:
export LD_ASSUME_KERNEL=2.2.5

Additionally, Redhat Linux 9.0 users should use the same setting, to avoid
stability problems.


----------------------------
Enabling SSI and CGI Support:
----------------------------

Having CGI and SSI available to web applications created security problems when
using a security manager (as a malicious web application could use them to
sidestep the security manager access control). In Tomcat 5.0, they have been
disabled by default, as our goal is to provide a fully secure default
configuration. However, CGI and SSI remain available.


To enable CGI:
* rename the file $CATALINA_HOME/server/lib/servlets-cgi.renametojar to
  $CATALINA_HOME/server/lib/servlets-cgi.jar.
* in $CATALINA_HOME/conf/web.xml, you will need to uncomment 2 areas, the
  servlet declaration and the servlet mapping. The servlet declaration
  looks similar to this:
    <servlet>
        <servlet-name>cgi</servlet-name>
        ...
    </servlet>

  While the servlet mapping looks similar to this:
    <servlet-mapping>
        <servlet-name>cgi</servlet-name>
        <url-pattern>/cgi-bin/*</url-pattern>
    </servlet-mapping>

  Alternately, these servlet declarations and mappings
  can be added to your web application deployment descriptor.

To enable SSI:
* rename the file $CATALINA_HOME/server/lib/servlets-ssi.renametojar to
  $CATALINA_HOME/server/lib/servlets-ssi.jar.
* in $CATALINA_HOME/conf/web.xml, you will need to uncomment 2 areas, the
  servlet declaration and the servlet mapping. The servlet declaration
  looks similar to this:
    <servlet>
        <servlet-name>ssi</servlet-name>
        ...
    </servlet>

  While the servlet mapping looks similar to this:
    <servlet-mapping>
        <servlet-name>ssi</servlet-name>
        <url-pattern>*.shtml</url-pattern>
    </servlet-mapping>

  Alternately, these servlet declarations and mappings
  can be added to your web application deployment descriptor.



---------------------
Security manager URLs:
---------------------

The URLs to be used in the policy file to grant permissions to JARs located
inside the web application repositories have changed as of Tomcat 4.1.

In Tomcat 4.0, codeBase URLs for JARs loaded from web application
repositories were:
jar:file:${catalina.home}/webapps/examples/WEB-INF/lib/driver.jar!/-

In Tomcat 4.1 and 5.0, they should be:
file:${catalina.home}/webapps/examples/WEB-INF/lib/driver.jar


---------------------------
Symlinking static resources:
---------------------------

By default, Unix symlinks will not work when used in a web application to link
resources located outside the web application root directory.

This behavior is optional, and the "allowLinking" flag may be used to disable
the check.


------------------------
Enabling invoker servlet:
------------------------

Starting with Tomcat 4.1.12, the invoker servlet is no longer available by
default in all webapps. Enabling it for all webapps is possible by editing
$CATALINA_HOME/conf/web.xml to uncomment the "/servlet/*" servlet-mapping
definition.

Using the invoker servlet in a production environment is not recommended and
is unsupported.

------------------------
Viewing the Tomcat Change Log 
------------------------

The Change Log for tomcat 5 is available at
http://jakarta.apache.org/tomcat/tomcat-5.0-doc/changelog.html.

-------------------
When all else fails:
-------------------

See the FAQ
http://jakarta.apache.org/tomcat/faq/