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Apache Tomcat

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Apache Tomcat
Developer(s)Apache Software Foundation
Stable release
6.0.29[1] / July 22, 2010; 14 years ago (2010-07-22)
Preview release
7.0.5 beta[2] / December 1, 2010; 14 years ago (2010-12-01)
Repository
Written inJava
Operating systemCross-platform
TypeServlet container
HTTP web server
LicenseApache License 2.0
Websitehttp://tomcat.apache.org

Apache Tomcat (or Jakarta Tomcat or simply Tomcat) is an open source servlet container developed by the Apache Software Foundation (ASF). Tomcat implements the Java Servlet and the JavaServer Pages (JSP) specifications from Sun Microsystems, and provides a "pure Java" HTTP web server environment for Java code to run.

Tomcat should not be confused with the Apache web server, which is a C implementation of an HTTP web server; these two web servers are not bundled together. Apache Tomcat includes tools for configuration and management, but can also be configured by editing XML configuration files.

Components

Tomcat version 4.x was released with Catalina (a servlet container), Coyote (an HTTP connector) and Jasper (a JSP engine).

Catalina

Catalina is Tomcat's servlet container. Catalina implements Sun Microsystems' specifications for servlet and JavaServer Pages (JSP). In Tomcat, a Realm element represents a "database" of usernames, passwords, and roles (similar to Unix groups) assigned to those users. Different implementations of Realm allow Catalina to be integrated into environments where such authentication information is already being created and maintained, and then utilize that information to implement Container Managed Security as described in the Servlet Specification. [3]

The architect for Catalina was Craig McClanahan.

Coyote

Coyote is Tomcat's HTTP Connector component that supports the HTTP 1.1 protocol for the web server or application container. Coyote listens for incoming connections on a specific TCP port on the server and forwards the request to the Tomcat Engine to process the request and send back a response to the requesting client.

Jasper

Jasper is Tomcat's JSP Engine. Tomcat 5.x uses Jasper 2, which is an implementation of the Sun Microsystems's JavaServer Pages 2.0 specification. Jasper parses JSP files to compile them into Java code as servlets (that can be handled by Catalina). At runtime, Jasper detects changes to JSP files and recompiles them.

Jasper 2

From Jasper to Jasper 2, important features were added:

  • JSP Tag library pooling - Each tag markup in JSP file is handled by a tag handler class. Tag handler class objects can be pooled and reused in the whole JSP servlet.
  • Background JSP compilation - While recompiling modified JSP Java code, the older version is still available for server requests. The older JSP servlet is deleted once the new JSP servlet has finished being recompiled.
  • Recompile JSP when included page changes - Pages can be inserted and included into a JSP at runtime. The JSP will not only be recompiled with JSP file changes but also with included page changes.
  • JDT Java compiler - Jasper 2 can use the Eclipse JDT (Java Development Tools) Java compiler instead of Ant and javac.

Features

Tomcat 5.x

  • Implements the Servlet 2.4 and JSP 2.0 specifications
  • Reduced garbage collection, improved performance and scalability
  • Native Windows and Unix wrappers for platform integration
  • Faster JSP parsing

Deployment

Experienced users can build and install Tomcat manually from source code after installing such dependencies as the Java Development Kit and the Apache Ant build tool.

Depending on the usage requirements, Tomcat may either be deployed as a standalone pure-Java web server or as a component in a more complex configuration in which it serves as a back-end which handles requests passed to it from a general purpose web server such as Apache, using a connector such as mod_jk.

History

Tomcat started off as a servlet reference implementation by James Duncan Davidson, a software architect at Sun Microsystems. He later helped make the project open source and played a key role in its donation by Sun to the Apache Software Foundation. The Apache Ant software build automation tool was developed as a side-effect of the creation of Tomcat as an open source project.

Davidson had initially hoped that the project would become open sourced and, since many open source projects had O'Reilly books associated with them featuring an animal on the cover, he wanted to name the project after an animal. He came up with Tomcat since he reasoned the animal represented something that could fend for itself. Although the tomcat was already in use for another O'Reilly title, his wish to see an animal cover eventually came true when O'Reilly published their Tomcat book with a snow leopard on the cover.[4]


Version history

Apache Tomcat versions
Version Release Date Description
3.0.x. (initial release) 1999 Merger of donated Sun Java Web Server code and ASF and Implements Servlet 2.2 and JSP 1.1 specifications.
3.3.2 March 9, 2004 Latest 3.x release.
4.1.31 October 11, 2004
4.1.36 March 24, 2007
4.1.39 December 3, 2008
4.1.40 June 25, 2009 Latest 4.x release.
5.0.0 October 9, 2002
5.0.23
5.0.24 May 9, 2004
5.0.28 August 28, 2004
5.0.30 August 30, 2004
5.5.0 August 31, 2004
5.5.1 September 7, 2004
5.5.4 November 10, 2004
5.5.7 January 30, 2005
5.5.9 April 11, 2005
5.5.12 October 9, 2005
5.5.15 January 21, 2006
5.5.16 March 16, 2006
5.5.17 April 28, 2006
5.5.20 September 1, 2006
5.5.23 March 2007
5.5.25 September 2007
5.5.26 February 2008
5.5.27 September 8, 2008
5.5.28 September 4, 2009
5.5.30 July 9, 2010
5.5.31 September 16, 2010 Latest 5.x release.
6.0.0 December 1, 2006
6.0.10 March 1, 2007
6.0.13 May 15, 2007
6.0.14 August 13, 2007
6.0.16 February 7, 2008
6.0.18 July 31, 2008
6.0.20 June 3, 2009
6.0.24 January 21, 2010
6.0.26 March 11, 2010
6.0.28 July 9, 2010
6.0.29 July 22, 2010 Current stable version.
7.0.0 beta June 29, 2010 First Apache Tomcat release to support the Servlet 3.0, JSP 2.2, and EL 2.2 specifications.
7.0.4 beta October 21, 2010 Fourth beta version.
7.0.5 beta December 1, 2010 Current beta version.

Communities

Apache software is built in a community process, with both user and developer mailing lists. The developer list is where discussion on building and testing the next release takes place, while the user list is where users can discuss their problems with the developers and other users.

A number of free Apache Tomcat resources and communities have developed in 2010 including Tomcatexpert.com, a SpringSource sponsored community for developers and operators who are running Apache Tomcat in large-scale production environment's, and MuleSoft's Apache Tomcat Resource Center, where you can find instructional guides on installing, updating, configuring, monitoring, troubleshooting and securing various versions of Tomcat.

See also

References

  1. ^ "Apache Tomcat 6.0 - Changelog". Retrieved 2010-07-23.
  2. ^ "Apache Tomcat 7.0 - Changelog". Retrieved 2010-10-14.
  3. ^ http://tomcat.apache.org/tomcat-5.5-doc/config/realm.html
  4. ^ Jason Brittain, Ian F. Darwin, Tomcat: The Definitive Guide, O'Reilly Books, p. 322, ISBN 0-596-00318-8

Bibliography

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