1: HTTP Communication and Security with Silverlight (including Cross-Domain Communication)
Silverlight supports two types of security policy files:
– Flash policy file - crossdomain.xml policy file used by Adobe Flash.
– Silverlight policy file - clientaccesspolicy.xml file used by Silverlight_
_In Silverlight 3, the Silverlight runtime tries to open a connection using TCP to a well-known port (port 943) on the target site. If a TCP connection can be established, the Silverlight runtime sends the special string <policy-file-request/> to the server to request a Silverlight socket policy file. The Silverlight runtime then waits to receive a reply from the target site that contains a Silverlight policy file. _
In Silverlight 4, an application can choose instead to retrieve the policy file via the HTTP protocol on TCP port 80 instead of the custom TCP protocol on port 943. This allows HTTP servers that are already running HTTP services to authorize socket connections from Silverlight applications without having to deploy a new TCP service on the machine and open a port through a firewall for port 943.
_To deploy a socket policy file on a server for sockets in Silverlight 3, system administrators need to configure a separate authentication service on port 943 for each IP address that is to provide the policy file definition. _
To deploy a policy file on a server for sockets in Silverlight 4, system administrators can choose to use the above method on port 943 or use HTTP port 80. For use with HTTP, system administrators need to configure a web service for each IP address that is to provide the policy file definition and make the Silverlight policy file available over HTTP. The policy file for sockets must be stored in the "clientaccesspolicy.xml" file at the root of a web server that responds for the resolved IP address of the target connection request. …
6: Pushing Data to a Silverlight Client with Sockets: Part I (Silverlight 2)
7: Pushing Data to a Silverlight Client with Sockets: Part II (Silverlight 2)