Assets are images (GIF, JPEG, etc.), movies, sounds or other collateral associated with a web application. Assets come in three flavors: external, context and private.

External assets live at an arbitrary URL. Context assets use a URL within the servlet context hosting the Tapestry application; these assets are deployed within the same Web Application Archive (WAR) as the application.

Private assets come from the Java classpath and are resources not normally visible to the web server.

Tapestry uses the assets concept to address two areas: localization and deployment.

For localization: internal and private assets are localized, just like HTML templates. That is, the path name provided is used as the basis for a search that takes into account the desired locale. External assets can't be localized in this way.

Private assets allow for easy deployment because the assets are packaged with the HTML templates and Java code of the application, inside a Java Archive (JAR) file.

Private assets support re-usability; a re-usable component may be packaged with supporting assets (typically, image files) and used in any Tapestry application without change, and without having to locate, extract or otherwise fiddle with those assets.

The Tapestry framework provides two ways of exposing the assets to the client web browser.

First, it provides a service that will access the asset dynamically. The URL encodes the application servlet and the resource to download, and Tapestry framework code will pump the bytes down to the client web browser. This is the default behavior (and is most useful during development).

The second method involves copying the asset out to a directory visible to the web server, and creating a URL for it in its final location. This requires some extra configuration of the application. This method also has some implications when deploying new versions of the web application. These are addressed later in this document.