HTTP requests from Sling ESP scripts (Server side JavaScript based on Rhino)

Question

How can I make an HTTP request from a Sling ESP page? Is there something like JQuery or Node's http module that I can use? Or do I have to fall back to Java code?

(Sling ESP Pages are server side JavaScript pages running in the Rhino JavaScript engine)

Answer 1

When sling implements a script language it provides a limited set of bindings to commonly used objects. These are defined here:

http://sling.apache.org/apidocs/sling5/org/apache/sling/api/scripting/SlingBindings.html

In addition, Rhino implements several features to provide integration with java. Such as the Packages variable which contains all the top level java packages, such as java and com.This provides you with a way to interact with java directly from the esp, an example being.

Packages.java.util.Calendar.getInstance()

The details of this java interaction can be found here:

https://developer.mozilla.org/en-US/docs/Rhino/Scripting_Java?redirectlocale=en-US&redirectslug=Scripting_Java

So to answer your question. No, there isn't a supplied http module for you to use.

Your options are:

• Forgo the esp and write a java servlet.
• Use the Rhino/Java integration to write the HTTP call in the esp file using the relevant java objects.
• Encode the HTTP code into a re-usable OSGi service and use the java integration to access the service

My recommendation would be option 3 as it provides the best code portability, and is the closest to what I would consider the "sling" way of doing things. To access the service you would just use:

var service = sling.getService(Packages.foo.bar.HttpClient.class);

Answer 2

There's no out-of-the box service that you can use to make HTTP requests from a Sling script, but if an HTTP client bundle (such as those from http://hc.apache.org/) makes its classes available you can use them in any Sling script.

As JE Bailey says, that wouldn't be the most convenient thing so you could write an OSGi wrapper service to make this easier. And maybe contribute that to Sling (hint, hint ;-)

If you want to make requests to Sling itself you can use the SlingRequestProcessor service which bypasses HTTP and makes internal requests to Sling directly.