Flex - RPC

Remote Procedure Call Services:

RPC services let your flex application to interact with the remote servers to provide data to your application or for your application to send data to the server.

Using Flex SDK, you can access the remote data through web services like SOAP or normal HTTP services like GET or POST requests.

For security, by default flash player doesn’t allow an application to access a remote data source from a domain other than the domain from which the application was served.

Therefore a remote server must either be in the same domain as the server hosting your application or the remote server must define a crossdomain.xml file.

Crossdomain.xml file is an xml file that provides access to swf files from certain domains or from all domains.