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The namespace attribute subdivides action configurations into logical modules, each with its own identifying prefix. Namespaces avoid conflicts between action names. Each namespace can have its own "menu" or "help" action, each with its own implementation. While the prefix appears in the browser URI, the tags are "namespace aware", so the namespace prefix does not need to be embedded in forms and links.

Default Namespace

The default namespace is "" - an empty string. The default namespace is used as a "catch-all" namespace. If an action configuration is not found in a specified namespace, the default namespace is also be searched. The local/global strategy allows an application to have global action configurations outside of the action element "extends" hierarchy.

The namespace prefix can be registered with Java declarative security, to ensure only authorized users can access the actions in a given namespace.

Root Namespace

A root namespace ("/") is also supported. The root is the namespace when a request directly under the context path is received. As with other namespaces, it will fall back to the default ("") namespace if a local action is not found.

Namespace Example

Namespaces

Namespaces are a important concept that help manage large applications with hundreds of actions. Within the Web, namespaces are managed by paths. When a request comes in, the ServletDispatcher will extract the action and namespace to determine the appropriate action to execute. For more information regarding namespaces, please refer to the xwork docs regarding namespaces(see XW:Namespaces). Below gives a short example of using namespaces with webwork.

Note: If a request is made to /barspace/foo.action, the action foo will be searched for in a namespace of /barspace. If the action is not found, the action will then be searched for in the default namespace. Unless specified, the default namespace will be "". In our example below, their is no action foo in the namespace /barspace, therefore the default will be searched and /foo.action will be executed.

Namespace example

<package name="default">

    <action name="foo" class="mypackage.simpleAction>simpleAction">
        <result name="success" type="dispatcher">greeting.jsp</result>
    </action>

    <action name="bar" class="mypackage.simpleAction"> 
        <result name="success" type="dispatcher">bar1.jsp</result> 
    </action>
</package>

<package name="mypackage1" namespace="/">
    <action name="moo" class="mypackage.simpleAction">
        <result name="success" type="dispatcher">moo.jsp</result>
    </action>
</package>


<package name="barmypackage2" namespace="/barspace"> 

    <action name="bar" class="mypackage.simpleAction"> 
        <result name="success" type="dispatcher">bar2.jsp</result> 
    </action> 

</package>

...

How the Code Works

If a request for /barspace/bar.action is made, the /barspace namespace is searched for the bar action. If found, the bar action is executed, else it will fall back to the default namespace. In the Namespace Example, the bar action does exist in the /barspace namespace, so the bar action will be executed, and if "success" is returned, the request will be forwarded to bar2.jsp.

In the Namespace Example, if a request for moo.action is made, the root namespace ('/') is searched for a moo action; if a root action is not found, the default namespace is checked. In this case, the moo action does exist and will be executed. Upon success, the request would be forwarded to bar2.jsp.