Template

In Tiles, a template is the layout part of a page. You can see as a page structure with some gaps, called attributes, to be filled.

For instance, consider the "classic layout" page structure.

You can replicate this structure by creating a JSP page, as you can see below.

<%@ taglib uri="http://tiles.apache.org/tags-tiles" prefix="tiles" %>
<table>
  <tr>
    <td colspan="2">
      <tiles:insertAttribute name="header" />
    </td>
  </tr>
  <tr>
    <td>
      <tiles:insertAttribute name="menu" />
    </td>
    <td>
      <tiles:insertAttribute name="body" />
    </td>
  </tr>
  <tr>
    <td colspan="2">
      <tiles:insertAttribute name="footer" />
    </td>
  </tr>
</table>

Notice that a template can have no attributes: in this case it can be used directly.

Attribute

An attribute is a gap in a template that needs to be filled in your application. An attribute can be of three types:

• string: it is a string to be directly rendered as it is.
• template: it is a template, with or without attributes. If it has attributes, you have to fill them too to render a page.
• definition: it is a reusable composed page, with all (or some) attributes filled (see below).

Definition

A definition is a composition to be rendered to the end user; essentially a definition is composed of a template and completely or partially filled attributes.

• If all of its attributes are filled, it can be rendered to the end user.
• If not all of its attributes are filled, it is called an abstract definition, and it can be used as a base definition for extended definitions, or their missing attributes can be filled at runtime.

For example, you can create a page using the classic layout as seen before, by modifying the Tiles configuration file.

<definition name="myapp.homepage" template="/layouts/classic.jsp">
  <put-attribute name="header" value="/tiles/banner.jsp" />
  <put-attribute name="menu" value="/tiles/common_menu.jsp" />
  <put-attribute name="body" value="/tiles/home_body.jsp" />
  <put-attribute name="footer" value="/tiles/credits.jsp" />
</definition>

View Preparer

Sometimes a definition, before it is rendered, needs to be "prepared". For example when showing a menu, the menu structure must be created and stored in the request scope.

For this reason, a View Preparer can be used: it is called before the definition is rendered, so all the things needed to render correctly the definition can be prepared.

See the Tiles View Preparer configuration for more information.