Sling Servlet 03: Servlet Resource Provider

Servlet Resource Provider

A service listener org.apache.sling.servlets.resolver.internal.SlingServletResolver listens for the OSGi services implementing javax.servlet.Servlet interface and registers its reference.

When a request hits the server, this SlingServletResolver kicks in to execute its sling script resolution procedure to choose the right servlet to respond to the request.

Each individual servlet will have a dedicated service instance of ServletResourceProvider associated with it, which will provide ServletResources in the resource tree, based on the servlet's registration properties.

The actual resource path of such resources differs for servlets registered by type and those registered by path:

Servlet registered by	Full Resource Path
Path	(given path).servlet
ResourceType	for each selector, extension and method combination one resource with path resource type[/[<selector with separator '/'>.][extension][method]].servlet'.

If multiple servlets are registered for the same metadata the one with the highest service ranking is returned in the virtual resource tree.

The resources expose the following properties:

Property Name	Description
sling:resourceType	The resource type to which the servlet is registered. It is equal to the absolute resource path.
sling:resourceSuperType	The resource superType. Is sling/bundle/resource if not explicitly set.
servletName	The name of the servlet.
servletClass	The fully-qualified class name of the underlying servlet.

In addition, each such resource can be adapted to a Servlet.

Reference: Servlets and Scripts

Conclusion

In this short theoretical post, we discussed the details of a Servlet Resource Provider. You can find the complete code on my GitHub.