You can check How to set up CAS Rest api with JDBC Authentication. for setting up CAS server for your application. Now if you want to test if your CAS server is working properly for REST calls then you can use the following code and you need to check for the following things. You need to make a GET or POST call depending on your CAS...
You can allow Cross Domain Ajax calls to an application by just registering a new filter and then configure it to Allow-Origin : {your domain's} or you can use a wild card "*" to allow the calls from all domains. You can even Define the Custom Headers your application supports by defining them in a comma separated format ,...