TOMCAT

Apache Tomcat (or simply Tomcat, formerly also Jakarta Tomcat) is an open source web server and servlet container developed by the Apache Software Foundation (ASF). Tomcat implements the Java Servlet and the JavaServer Pages (JSP) specifications from Oracle Corporation, 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, although they are frequently used together as part of a server application stack. Apache Tomcat includes tools for configuration and management, but can also be configured by editing XML configuration files.

Tomcat4.x was released with Catalina ( servlet container), Coyote (an HTTP connector) and Jasper (a JSP engine).

[edit]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 use that information to implement Container Managed Security as described in the Servlet Specification. ^[2]

[edit]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.

[edit]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.

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.

[edit]Features

Tomcat 7.x implements the Servlet 3.0 and JSP 2.2 specifications.^[3] It requires Java version 1.6, although previous versions have run on Java 1.1 through 1.5. Versions 5 through 6 saw improvements ingarbage collection, JSP parsing, performance and scalability. Native wrappers, known as "Tomcat Native", are available for Microsoft Windows and Unix for platform integration.

[edit]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 supplied by the Apache Tomcat team, or mod_proxy an optional module for the Apache HTTP Server supplied by the Apache HTTP Server team. Apache Tomcat (or simply Tomcat, formally also Jakarta Tomcat) is an open source web server and servlet container developed by the Apache Software Foundation (ASF). Tomcat implements the Java Servlet and the Java Server Pages (JSP) specifications from Oracle Corporation, 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, although they are frequently used together as part of a server application stack. Apache Tomcat includes tools for configuration and management, but can also be configured by editing XML configuration files.

Tomcat is an application, a product of Software foundation, that enables you to make a standalone PC work as a Server. This helps in tasks such as programming using Java Server Pages (JSP). By installing this software you can use your PC as a server and do any related task that a server does. To avail this benefit you need to download and install Tomcat (6.0 is the latest version) and configure it thereafter. 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 Apache Software Foundation. The Apache Ant software build automation tool was developed as a side-effect of the creation of Tomcat book with a snow leopard on the cover.

Davidson had initially hoped that the project would become open sourced and since many open source project had O’Reilly books associated with them featuring an animal in 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. Apache Tomcat is an open source software implementation of the Java Servlet and the Java Server Pages technologies. The Java Servlet and Java Server Pages specifications are developed under the Java Community Process Apache Tomcat developed in an open and participatory environment and released under the Apache License Version 2. Apache Tomcat is intended to be a collaboration of the best-of-breed developers from around the world. Apache Tomcat powers numerous large-scale, mission-critical web applications across a diverse range of industries and organizations.

[edit]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]