Following the guidelines laid out in the Java EE specification, these grouped components operate within a runtime environment, which is made up of a number of different Java containers. These containers are specialized implementations of the Java container model, in which a given Java class is responsible for managing interactions with a group of sub-classes. This model offers a number of benefits, including security by isolating classes from one another, portability by decoupling the actual brokering of transactions from the application itself , logical structure by using hierarchical permissions control and inherited configuration , and modularity by using standard APIs to allow any type of container to communicate with any other container.
However, from a purely functional standpoint, the most important benefit of container management is that each container provides its own persistence control, allowing dynamically-generated user state to be logically preserved across all of an application's components. Because they are assembled from various discrete technologies, the complexity of a Java web application can vary from extremely simple, using only one or two components, to very complex, incorporating multiple data sources, transformations, server calls, and interoperating functions.
A simple web application might consist of a single JSP page, which contains a single Java call - for example, a request for the current date. A more complicated example might include static HTML pages, JSP pages, servlets for processing user input, JNDI resources such as databases and user realms, multiple data sources that require complex security and data transformation operations to communicate with, and more.
The other advantage of managing web applications with containers is that all configuration differences, additional components, and so on, are managed with the same standards. This allows a single web application to be deployed on any implementation of the Java EE Application Server specification without minimal changes to its internal code.
This is made possible, in part, by standard directory structure. Java web applications conform to a standard directory structure, specified in the Java EE specification, which designates exactly where specific Java objects should be placed within a program.
This method is used for three reasons. First of all, standard directory structure is designed to integrate non-web Java directory idioms with the needs of a web container.
In Java, a correlation between class names and directory structure helps the classloader locate and load the libraries it needs. In the Java servlet specification, this idea is preserved and extended to make the deployment and loading of applications and classes on the server a more logical process. Before compression, which we will discuss below, all web applications share the following basic directory elements:.
This is the root directory of the web application. In addition to the WEB-INF directory, which we discuss below, this directory includes any resource that should be visible to the web container in other other words, items that are directly accessible via a URL. These files can be loosely collected within the Document Root or organized into subfolders.
This directory, which is contained within the Document Root, is invisible from the web container. It contains all resources needed to run the application, from Java classes, to JAR files and libraries, to other supporting files that the developer does not want a web user to access.
This folder also contains the application's deployment descriptor, an important XML file discussed below. This directory, contained within WEB-INF, is a repository of all the Java classes and packages required by the application other than those contained in Tomcat's common or shared class repositories.
These will be loaded when Tomcat starts the application, and are only visible to this application. Class files can be organized into packages within this directory, as long as they are organized with the standard Java naming structure. This directory contains JAR files required by the web application.
Classes contained in these files will be decompressed and loaded at application start up. This file, known as the "deployment descriptor" is an important XML configuration file, which is read by Tomcat when the application is first deployed. This file contains a list of all servlets and resources required by the application, in a hierarchical format that can be used to define security constraints, map servlets to specific URLs, and more.
In Tomcat, a Context represents a single web application. Viewed 40k times. File ". Problem is I am not able to read filePath in Linux using 1st method relative path process. Is there any way to read file using relative path in tomcat from Linux env?.
Improve this question. Vadim Kotov 7, 8 8 gold badges 45 45 silver badges 61 61 bronze badges. The code should work anywhere.
Which error do you get? Did you try System. Aaron Digulla-- My code is working fine in windows and Linux , while using System. My question is how to get relative path in Linux from Tomcat web app.
Add a comment. Active Oldest Votes. Next, I'm using getAbsoluteFile to make sure I get a useful path in exceptions. Improve this answer. Aaron Digulla Aaron Digulla k gold badges silver badges bronze badges. This solution seems to work only in "regular" installations of Tomcat. The actual webapp is in another dir.
David Levesque David Levesque Sign up or log in Sign up using Google. Sign up using Facebook. A Context configuration '. Here is an example for Tomcat running on Windows:. When used to select a web application '. Here is an example of installing an application using a Context configuration '.
The name of the WAR file without the '. Use the Browse button to select a WAR file to upload to the server from your local desktop system. If a war file of the same name already exists in your Host's appBase the upload will fail. Either undeploy the existing war file from your Host's appBase or upload the new war file using a different name. The war file upload or install failed with a Java Exception.
The exception message will be listed. For security when untrusted users can manage web applications, the Host deployXML flag can be set to false. This prevents untrusted users from installing web applications using a configuration XML file and also prevents them from installing application directories or '. The context paths for all currently running web applications must be unique.
Therefore, you must either undeploy the existing web application using this context path, or choose a different context path for the new one. An exception was encountered trying to start the new web application. If the Host deployXML flag is set to false this error will happen if an attempt is made to install a web application directory or '. The find leaks diagnostic triggers a full garbage collection. It should be used with extreme caution on production systems.
The find leaks diagnostic attempts to identify web applications that have caused memory leaks when they were stopped, reloaded or undeployed. Results should always be confirmed with a profiler. The diagnostic uses additional functionality provided by the StandardHost implementation.
It will not work if a custom host is used that does not extend StandardHost. This diagnostic will list context paths for the web applications that were stopped, reloaded or undeployed, but which classes from the previous runs are still present in memory, thus being a memory leak.
If an application has been reloaded several times, it may be listed several times. Explicitly triggering a full garbage collection from Java code is documented to be unreliable. If you want to make sure, that the diagnostics were successfully running a full GC, you will need to check using tools like GC logging, JConsole or similar.
This section displays information about Tomcat, the operating system of the server Tomcat is hosted on, the Java Virtual Machine Tomcat is running in, the primary host name of the server may not be the host name used to access Tomcat and the primary IP address of the server may not be the IP address used to access Tomcat. Tomcat Server 8 Apache Tomcat Server 8. The interface is divided into six sections: Message - Displays success and failure messages.
Manager - General manager operations like list and help. Applications - List of web applications and commands. Deploy - Deploying web applications. Diagnostics - Identifying potential problems. Server Information - Information about the Tomcat server. Message Displays information about the success or failure of the last web application manager command you performed. Manager The Manager section has three links: List Applications - Redisplay a list of web applications. Applications The Applications section lists information about all the installed web applications and provides links for managing them.
For each web application the following is displayed: Path - The web application context path.
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