Recurly.js is a Javascript library which allows you to easily embed and customize PCI compliant forms within your website. HMAC digital signatures are used to verify information sent to Recurly via your user's browser. The signature validates that parameters you have specified in your HTML have not been tampered with before being received by Recurly. The Recurly JS Client Library consists of helper methods to create and verify signatures.
The sample application is a simple Spring Roo application which follows the Maven project structure.
Assuming you have maven installed, start the sample application by running the following from the root directy of the project:
mvn tomcat:run
Open a browser and go to http://localhost:8080/recurly-integration-sample-app