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Apache Tomcat Version 7.0.73
* Dependency Changes
* API Stability
* 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
* Viewing the Tomcat Change Log
* Cryptographic software notice
* When all else fails
Tomcat 7.0 is designed to run on Java SE 6 and later.
In addition, Tomcat 7.0 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.
The public interfaces for the following classes are fixed and will not be
changed at all during the remaining lifetime of the 7.x series:
The public interfaces for the following classes may be added to in order to
resolve bugs and/or add new features. No existing interface will be removed or
changed although it may be deprecated.
Note: As Tomcat 7 matures, the above list will be added to. The list is not
considered complete at this time.
The remaining classes are considered part of the Tomcat internals and may change
without notice between point releases.
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
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.
A standard installation of Tomcat 7.0 makes all of the following APIs available
for use by web applications (by placing them in "lib"):
* annotations-api.jar (Annotations package)
* catalina.jar (Tomcat Catalina implementation)
* catalina-ant.jar (Tomcat Catalina Ant tasks)
* catalina-ha.jar (High availability package)
* catalina-tribes.jar (Group communication)
* ecj-4.4.2.jar (Eclipse JDT Java compiler)
* el-api.jar (EL 2.2 API)
* jasper.jar (Jasper 2 Compiler and Runtime)
* jasper-el.jar (Jasper 2 EL implementation)
* jsp-api.jar (JSP 2.2 API)
* servlet-api.jar (Servlet 3.0 API)
* tomcat7-websocket.jar (WebSocket 1.1 implementation)
* tomcat-api.jar (Interfaces shared by Catalina and Jasper)
* tomcat-coyote.jar (Tomcat connectors and utility classes)
* tomcat-dbcp.jar (package renamed database connection pool based on Commons DBCP)
* tomcat-jdbc.jar (Tomcat's database connection pooling solution)
* tomcat-util.jar (Various utilities)
* websocket-api.jar (WebSocket 1.1 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.
To override the XML parser implementation or interfaces, use the endorsed
mechanism of the JVM. The default configuration defines JARs located in
"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:
Redhat Linux 9.0 users should use the following setting to avoid
There are some Linux bugs reported against the NIO sendfile behavior, make sure you
have a JDK that is up to date, or disable sendfile behavior in the Connector.
6427312: (fc) FileChannel.transferTo() throws IOException "system call interrupted"
5103988: (fc) FileChannel.transferTo should return -1 for EAGAIN instead throws IOException
6253145: (fc) FileChannel.transferTo on Linux fails when going beyond 2GB boundary
6470086: (fc) FileChannel.transferTo(2147483647, 1, channel) cause "Value too large" exception
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
Viewing the Tomcat Change Log:
See changelog.html in this directory.
Cryptographic software notice
This distribution includes cryptographic software. The country in
which you currently reside may have restrictions on the import,
possession, use, and/or re-export to another country, of
encryption software. BEFORE using any encryption software, please
check your country's laws, regulations and policies concerning the
import, possession, or use, and re-export of encryption software, to
see if this is permitted. See for more
The U.S. Government Department of Commerce, Bureau of Industry and
Security (BIS), has classified this software as Export Commodity
Control Number (ECCN) 5D002.C.1, which includes information security
software using or performing cryptographic functions with asymmetric
algorithms. The form and manner of this Apache Software Foundation
distribution makes it eligible for export under the License Exception
ENC Technology Software Unrestricted (TSU) exception (see the BIS
Export Administration Regulations, Section 740.13) for both object
code and source code.
The following provides more details on the included cryptographic
- Tomcat includes code designed to work with JSSE
- Tomcat includes code designed to work with OpenSSL
When all else fails:
See the FAQ