# Dynamic Web projects and applications

There are two types of Web projects: dynamic and static. Dynamic web projects can contain dynamic J2EE resources such as servlets, JSP files, filters, and associated metadata, in addition to static resources such as images and HTML files. Static web projects only contains static resources. When you create Web projects, you can include cascading style sheets and JSP tag libraries (for dynamic Web projects), so that you can begin development with a richer set of project resources.

Dynamic Web projects are always imbedded in Enterprise Application projects. The wizard that you use to create a dynamic Web project will also create an Enterprise Application (EAR) project if it does not already exist. The wizard will also update the application.xml deployment descriptor of the specified Enterprise Application project to define the Web project as a module element. If you are importing a WAR file rather than creating a dynamic Web project new, the WAR Import wizard requires that you specify a Web project, which already requires an EAR project.

J2EE conventions may represent extra overhead if you only want to create a static, content-based Web application, which contains no dynamic files, such as JSP files or servlets. In this case, when you need only the most basic Web project, you might want to use the static Web project type (see Static Web projects). Note that static Web projects can be converted to dynamic Web projects by selecting Convert to a Dynamic Web Project, from the Project menu.

The J2EE model, and more specifically, the Sun Microsystems Java™ Servlet 2.3 Specification, defines a Web application directory structure that specifies the location of Web content files, class files, class paths, deployment descriptors, and supporting metadata. The Web project hierarchy mirrors that of the Web application created from a project. In the workbench, you can use the New Web Project wizard to create a new Web project.

The main project folder contains all development objects related to a Web application. The Web content folder contains the elements of the project necessary to create a Web application. This folder structure maps to the Web application archive (WAR) structure defined by Sun Microsystems.. The following default elements are located in the Web project folder hierarchy:
Note: In the Project Explorer view, Web projects are filtered into folder nodes to customize the display of Web resources for easy management during development. For information on the filtered structure, see Project Explorer view.

Web Deployment Descriptor
  The standard Web application deployment descriptor (the web.xml file).
JavaSource
  Contains the project's Java source code for classes, beans, and servlets. When these resources are added to a Web project, they are automatically compiled and the generated files are added to the WEB-INF/classes directory. The contents of the source directory are not packaged in WAR files unless an option is specified when a WAR file is created.
  Note: Though the default name given to the folder is JavaSources, you can change the name through the Project Explorer view or through the Preferences page available by selecting Window > Preferences > Web Tools > New J2EE Project.
imported_classes folder
  This folder may be created during a WAR import, and contains class files that do not have accompanying source. The imported_classes folder is a Java classes folder; Java classes folders can also be created using the Web project Java Build Path properties page.
WebContent folder
  The mandatory location of all Web resources, including HTML, JSP, graphic files, and so on. If the files are not placed in this directory (or in a subdirectory structure under this directory), the files will not be available when the application is executed on a server. The Web content folder represents the contents of the WAR file that will be deployed to the server. Any files not under the Web content folder are considered development-time resources (for example, .java files, .sql files, and .mif files), and are not deployed when the project is unit tested or published.
  Note: Though the default name given to the folder is WebContent, you can change the name in the Project Explorer by right-clicking the folder and selecting Rename or from the Web page of the project's Properties dialog. In a dynamic Web project, changing the folder name will update the Java build output directory. You can change the preference for the default folder name to be applied when creating new Web projects by selecting Window > Preferences > Web Tools > New J2EE Project.
META-INF
  This directory contains the MANIFEST.MF file, which is used to map class paths for dependent JAR files that exist in other projects in the same Enterprise Application project. An entry in this file will update the run-time project class path and Java build settings to include the referenced JAR files.
theme
  The suggested directory for cascading style sheets and other style-related objects.
WEB-INF
  Based on the Sun Microsystems Java Servlet 2.3 Specification, this directory contains the supporting Web resources for a Web application, including the web.xml file and the classes and lib directories.
/classes
  This directory is for servlets, utility classes, and the Java compiler output directory. The classes in this directory are used by the application class loader to load the classes. Folders in this directory will map package and class names, as in: `/WEB-INF/classes/com/mycorp/servlets/MyServlet.class`.

  Do not place any .class files directly into this directory. The .class files are placed in this directory automatically when the Java compiler compiles Java source files that are in the Java Resources directory. Any files placed directly in this directory will be deleted by the Java compiler when it runs.

/lib
  The supporting JAR files that your Web application references. Any classes in .jar files placed in this directory will be available for your Web application
Libraries
  The supporting JAR files that your Web application references. This folder mirrors the content of the lib folder. In addition, Web Library Projects, which are "virtual" JAR files that do not physically reside in the Web project, but are associated with Java projects elsewhere in your workspace, are included in this folder. They are packaged with your project when you export the application's WAR file.

Note: A library entry on the Java build path will remain there unless the actual JAR file is deleted from the WEB-INF/lib folder. If you remove a library path entry but not the JAR file, the library entry will be re-added to the path automatically.
Related concepts

Web application overview
Web development tools
Static Web projects
Web archive (WAR) files

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