CQ & Sling servlets: old legacy URL

SlingIn this short article (first of a serie I hope) I’ll show you how to create a Sling Servlet in CQ.

Scenario

You are migrating your existing application in CQ a piece at time and it’s time for the Servlets (controllers) part, so for the first stage you’d like to keep the old URLs. Maybe because some other external services are calling you at these coordinates or because you don’t want to enter each jsp and change the forms action.

Ingredients

  • CQ instance running in Author (localhost:4502)
  • CRXDE (let’s ease the game for starting)

Process

Create a new OSGi bundle under geometrixx (or your app). In this create a new class that extends the SlingSafeMethodsServlet.
Then you have to register as a service in the OSGi container. This is done using the Felix annotations as following:

/**
 * @scr.component immediate="true" metatype="false"
 * @scr.service interface="javax.servlet.Servlet"
 * @scr.property name="sling.servlet.methods" values.0="GET"
 * @scr.property name="sling.servlet.paths" values.0="/path/to/my/servlet"
 *                                          values.1="/apps/path/to/my/servlet"
 */

I’ll leave you to the references section of this post for getting deeper into the meaning of each.

At the end your code will look something like the following:

package com.samples.sling;

import java.io.IOException;
import javax.servlet.ServletException;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.servlets.SlingSafeMethodsServlet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @scr.component immediate="true" metatype="false"
 * @scr.service interface="javax.servlet.Servlet"
 * @scr.property name="sling.servlet.methods" values.0="GET"
 * @scr.property name="sling.servlet.paths" values.0="/path/to/my/servlet"
 *                values.1="/apps/path/to/my/servlet"
 */
public class AbsoluteUrlServlet extends SlingSafeMethodsServlet {
   private static final long serialVersionUID = -1920460619265757059L;
   private static final Logger logger = LoggerFactory.getLogger(AbsoluteUrlServlet.class);

   @Override
   protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException, IOException {
      logger.debug("AbsoluteUrlServlet::doGet()");
      response.setContentType("text/plain");
      response.getOutputStream().print("Hello AbsoluteUrlServlet World!");
   }
}

Looking at the sling.servlet.paths annotation we se on which url we are actually mapping the servlet: /path/to/my/servlet and /apps/path/to/my/servlet.

Building the bundle and CRXDE+felix will do the magic of the deployment.

Now if you try to run localhost:4502/apps/path/to/my/servlet you’ll see our beautiful Helloworld, but if you’ll try to access localhost:4502/path/to/my/servlet you’ll get a 404 or a content listing.
This is due to a settings in felix+Sling. Open the felix console at the configuration tab (/system/console/configMgr) and search for Apache Sling Servlet/Script Resolver and Error Handler. Here you’ll have to add “/path/” to the Execution Paths section.

Done done!

References

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