There are a variety of HTTP-based web services. The main types
include:
To use a web service in ActionScript 3, you create a URLRequest
object, construct the web service call using either URL variables
or an XML document, and send the call to the service using a URLLoader
object. The Flex framework contains several classes that make it
easier to use web services—especially useful when accessing complex
SOAP services. Starting with Flash Professional CS3, you can use
the Flex classes in applications developed with Flash Professional
as well as in applications developed in Flash Builder.
In HTML-based AIR applications, you can use either the URLRequest
and URLLoader classes or the JavaScript XMLHttpRequest class. If
desired, you can also create a SWF library that exposes the web
service components of the Flex framework to your JavaScript code.
When your application runs in a browser, you can only use web
services in the same Internet domain as the calling SWF unless the
server hosting the web service also hosts a cross-domain policy
file that permits access from other domains. A technique that is
often used when a cross-domain policy file is not available is to
proxy the requests through your own server. Adobe Blaze DS and Adobe
LiveCycle support web service proxying.
In AIR applications, a cross-domain policy file is not required
when the web service call originates from the application security
sandbox. AIR application content is never served from a remote domain,
so it cannot participate in the types of attacks that cross-domain
policies prevent. In HTML-based AIR applications, content in the
application security sandbox can make cross-domain XMLHttpRequests.
You can allow content in other security sandboxes to make cross-domain
XMLHttpRequests as long as that content is loaded into an iframe.
