Tuesday, November 25, 2014


Apache Tomcat Servlet/JSP container.

Apache Tomcat version 7.0 implements the Servlet 3.0 and JavaServer Pages 2.2
$CATALINA_HOME: root of your Tomcat installation.
Optionally, Tomcat may be configured for multiple instances by defining $CATALINA_BASE for each instance. If multiple instances are not configured, $CATALINA_BASE is the same as $CATALINA_HOME.
These are some of the key tomcat directories:
/bin - Startup, shutdown, and other scripts. The *.sh files (for Unix systems) are functional duplicates of the *.bat files (for Windows systems).
/conf - Configuration files and related DTDs. The most important file in here is server.xml. It is the main configuration file for the container.
/logs - Log files are here by default.
/webapps - This is where your webapps go.
All of the information in the configuration files is read at startup, meaning that any change to the files necessitates a restart of the container.
Installing Tomcat on Windows can be done using the Windows installer.
Installation as a service:Tomcat is automatically started when Windows starts. For optimal security, the service should be run as a separate user, with reduced permissions.
Tomcat 7.0 was designed to run on Java SE 6.
set an environment variable CATALINA_HOME that contains the pathname to the directory in which Tomcat has been installed. Optionally, if Tomcat has been configured for multiple instances, each instance will have its own CATALINA_BASE configured.
WAR: Web Application Archive
A web application is defined as a hierarchy of directories and files in a standard layout. Such a hierarchy can be accessed in its "unpacked" form, where each directory and file exists in the filesystem separately, or in a "packed" form known as a Web ARchive, or WAR file.
The top-level directory of your web application hierarchy is also the document root of your application. Here, you will place the HTML files and JSP pages that comprise your application's user interface. When the system administrator deploys your application into a particular server, he or she assigns a context path to your application. Thus, if the system administrator assigns your application to the context path
, then a request URI referring to
 will retrieve the index.html file from your document root.
document root directory:
    *.html, *.jsp, etc. - The HTML and JSP pages, along with other files that must be visible to the client browser (such as JavaScript, stylesheet files, and images) for your application. In larger applications you may choose to divide these files into a subdirectory hierarchy, but for smaller apps, it is generally much simpler to maintain only a single directory for these files.
    /WEB-INF/web.xml - The Web Application Deployment Descriptor for your application. This is an XML file describing the servlets and other components that make up your application, along with any initialization parameters and container-managed security constraints that you want the server to enforce for you.
    /WEB-INF/classes/ - This directory contains any Java class files (and associated resources) required for your application, including both servlet and non-servlet classes, that are not combined into JAR files. If your classes are organized into Java packages, you must reflect this in the directory hierarchy under /WEB-INF/classes/. For example, a Java class named com.mycompany.mypackage.MyServlet would need to be stored in a file named /WEB-INF/classes/com/mycompany/mypackage/MyServlet.class.
    /WEB-INF/lib/ - This directory contains JAR files that contain Java class files (and associated resources) required for your application, such as third party class libraries or JDBC drivers.
When you install an application into Tomcat, the classes in the WEB-INF/classes/ directory, as well as all classes in JAR files found in the WEB-INF/lib/ directory, are made visible to other classes within your particular web application.
/WEB-INF/web.xml file contains the Web Application Deployment Descriptor for your application. It defines everything about your application that a server needs to know (except the context path, which is assigned by the system administrator when the application is deployed).
DTD: Document Type Descriptor
META-INF/context.xml file can be used to define Tomcat specific configuration options, such as an access log, data sources, session manager configuration and more.
In order to be executed, a web application must be deployed on a servlet container.
A web application can be deployed in Tomcat by one of the following approaches:
・Copy unpacked directory hierarchy into a subdirectory in directory $CATALINA_BASE/webapps/. Tomcat will assign a context path to your application based on the subdirectory name you choose.
・Copy the web application archive file into directory $CATALINA_BASE/webapps/. When Tomcat is started, it will automatically expand the web application archive file into its unpacked form, and execute the application that way.
・Use the Tomcat "Manager" web application to deploy and undeploy web applications. Tomcat includes a web application, deployed by default on context path /manager, that allows you to deploy and undeploy applications on a running Tomcat server without restarting it.
・Use "Manager" Ant Tasks In Your Build Script. Tomcat includes a set of custom task definitions for the Ant build tool that allow you to automate the execution of commands to the "Manager" web application.
・Use the Tomcat Deployer. Tomcat includes a packaged tool bundling the Ant tasks, and can be used to automatically precompile JSPs which are part of the web application before deployment to the server.
source code files

All of these components exist under a top level project source directory for your application:
    docs/ - Documentation for your application, in whatever format your development team is using.
    src/ - Java source files that generate the servlets, beans, and other Java classes that are unique to your application. If your source code is organized in packages (highly recommended), the package hierarchy should be reflected as a directory structure underneath this directory.
    web/ - The static content of your web site (HTML pages, JSP pages, JavaScript files, CSS stylesheet files, and images) that will be accessible to application clients. This directory will be the document root of your web application, and any subdirectory structure found here will be reflected in the request URIs required to access those files.
    web/WEB-INF/ - The special configuration files required for your application, including the web application deployment descriptor (web.xml, defined in the Servlet Specification), tag library descriptors for custom tag libraries you have created, and other resource files you wish to include within your web application. Even though this directory appears to be a subdirectory of your document root, the Servlet Specification prohibits serving the contents of this directory (or any file it contains) directly to a client request. Therefore, this is a good place to store configuration information that is sensitive (such as database connection usernames and passwords), but is required for your application to operate successfully.

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