AEM Sling Servlet: resourceTypes for POST & GET Code Example Code

When working with Sling Servlets in AEM, the choice between using a resource type or a sling path as the basis for your servlet’s operation is crucial. This article delves into the benefits of utilizing resource types and provides practical examples of how resource types can streamline your development process for both POST and GET templates.


Resource Type vs. Sling Path

The decision between using a resource type and a sling path as the foundation of your servlet’s functionality can significantly impact your development approach. A resource type is a more flexible and future-proof choice due to its abstraction from specific URLs. Resource types abstract the underlying storage structure, enabling your servlets to work consistently even if the content hierarchy changes. On the other hand, relying on sling paths can lead to brittle implementations, as they are tied to specific URLs that might change over time.


Advantages of Resource Types

  1. Abstraction: Resource types provide an abstraction layer, separating the servlet’s logic from the actual URL structure. This ensures that your servlet remains functional even when the content structure evolves.
  2. Adaptability: With resource types, your servlet can adapt to different parts of the content hierarchy without requiring modifications. This adaptability becomes crucial in scenarios where content structures are reorganized or repurposed.
  3. Consistency: By using resource types, you promote consistency in your application. Different components or pages with the same resource type can share the same servlet logic, enhancing maintainability.

Caveats when using @SlingServletPaths

  1. Path-bound servlets cannot be access-controlled using the default JCR repository ACLs.
  2. Path-bound servlets can only be registered to a path and not a resource type (i.e. no suffix handling).
  3. If a path-bound servlet is not active, e.g. if the bundle is missing or not started, a POST might result in unexpected results. usually creating a node at /bin/xyz which subsequently overlays the servlets path binding. The mapping is not transparent to a developer looking just at the repository.

POST Template using Resource Type

Consider a scenario where you want to handle form submissions via a POST request for multiple types of components. By utilizing resource types, you can create a centralized servlet that handles these submissions consistently, regardless of the content’s location.

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@Component(
    service = { Servlet.class },
    property = {
        "sling.servlet.resourceTypes=yourapp/components/form",
        "sling.servlet.methods=POST"
    }
)
public class FormSubmitServlet extends SlingAllMethodsServlet {
    @Override
    protected void doPost(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException, IOException {
        // Process form submission
        // ...

        // Send JSON response
        JSONObject jsonResponse = new JSONObject();
        jsonResponse.put("success", true);
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        response.getWriter().write(jsonResponse.toString());
    }
}

GET Template using Resource Type

Imagine you need to retrieve data from different types of resources, such as articles and videos, and display them using a single servlet. Utilizing resource types allows you to create a unified servlet to serve diverse content.

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@Component(
    service = { Servlet.class },
    property = {
        "sling.servlet.resourceTypes=yourapp/components/content",
        "sling.servlet.methods=GET"
    }
)
public class ContentDisplayServlet extends SlingSafeMethodsServlet {
    @Override
    protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException, IOException {
        // Fetch and render content
        // ...

        // Send JSON response
        JSONObject jsonResponse = new JSONObject();
        jsonResponse.put("success", true);
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        response.getWriter().write(jsonResponse.toString());
    }
}

Conclusion

Resource types stand as a powerful tool in AEM’s arsenal, offering a versatile and robust approach to developing Sling Servlets for both POST and GET templates. By abstracting the underlying URL structure, resource types enable consistent servlet behavior across different content hierarchies. This approach enhances code maintainability, adaptability, and future-proofing. In contrast, sling paths can result in rigid implementations tied to specific URLs. By embracing resource types, developers can create more flexible, reliable, and adaptable solutions in Adobe Experience Manager.


Hello, I am an enthusiastic Adobe Community Advisor and a seasoned Lead AEM Developer. I am currently serving as an AEM Technical Lead at MNPDigital.ca, bringing over a decade of extensive web engineering experience and more than eight years of practical AEM experience to the table. My goal is to give back to the AEM Full Stack Development community by sharing my wealth of knowledge with others. You can connect with me on LinkedIn.

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