============================= KNOWN ISSUES IN THIS RELEASE: =============================
* Dependency Changes * JNI Based Applications * Bundled APIs * Web application reloading and static fields in shared libraries * 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
=================== Dependency Changes: =================== Tomcat 5.5 is designed to run on J2SE 5.0 and later, and requires configuration to run on J2SE 1.4. Make sure to read the "RUNNING.txt" file in the fulldocs downloadable file(s) if you are using J2SE 1.4.
In addition, Tomcat 5.5 uses the Eclipse JDT Java compiler for compiling JSP pages. This means you no longer need to have the complete Java Development Kit (JDK) to run Tomcat, but a Java Runtime Environment (JRE) is sufficient. The Eclipse JDT Java compiler is bundled with the binary Tomcat distributions. Tomcat can also be configured to use the compiler from the JDK to compile JSPs, or any other Java compiler supported by Apache Ant.
======================= 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:
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.
============= Bundled APIs: ============= A standard installation of Tomcat 5.5 makes all of the following APIs available for use by web applications (by placing them in "common/lib" or "shared/lib"): * commons-el.jar (Commons Expression Language 1.0) * commons-logging-api.jar (Commons Logging API 1.0.x) * jasper-compiler.jar (Jasper 2 Compiler) * jasper-compiler-jdt.jar (Eclipse JDT Java compiler) * jasper-runtime.jar (Jasper 2 Runtime) * jsp-api.jar (JSP 2.0 API) * naming-common.jar (JNDI Context implementation) * naming-factory.jar (JNDI object factories for J2EE ENC support) * naming-factory-dbcp.jar (DataSource implementation based on commons-dbcp) * naming-resources.jar (JNDI DirContext implementations) * servlet-api.jar (Servlet 2.4 API)
Installing the compatibility package will add the following to the list, which are needed when running on J2SE 1.4: * jmx.jar (Java Management Extensions API 1.2 or later) * xercesImpl.jar (Xerces XML Parser, version 2.6.2 or later)
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.
To override the XML parser implementation or interfaces, use the endorsed mechanism of the JVM. The default configuration defines JARs located in "common/endorsed" as endorsed.
================================================================ 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).
================ Tomcat on Linux: ================ GLIBC 2.2 / Linux 2.4 users should define an environment variable: export LD_ASSUME_KERNEL=2.2.5
Redhat Linux 9.0 users should use the following setting to avoid stability problems: export LD_ASSUME_KERNEL=2.4.1
============================= Enabling SSI and CGI Support: ============================= Because of the security risks associated with CGI and SSI available to web applications, these features are disabled by default.
To enable and configure CGI support, please see the cgi-howto.html page.
To enable and configue SSI support, please see the ssi-howto.html page.
====================== Security manager URLs: ====================== In order to grant security permissions to JARs located inside the web application repository, use URLs of of the following format in your policy file:
============================ 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.