Information technology – UPnP device architecture – Part 18-12: Remote Access Device Control Protocol – Remote Access Discovery Agent Synchronization Service
|Publication Date:||1 August 2011|
|ICS Code (Interface and interconnection equipment):||35.200|
Overview and Scope
This service definition is compliant with the UPnP Device Architecture version 1.0. It defines a service type referred to herein as RADASync service.
This service type enables an in-band synchronization mechanism between Remote Access Clients and Remote Access Server.
A Remote Access Discovery Agent (RADA) aggregates information about UPnP devices and services from two primary sources, depending if the devices are located in the local network or they are located in a remote device. For aggregating the devices and services available in the local network, the Remote Access Discovery Agent is constantly monitoring the SSDP traffic, which enables the RADA to have an up-to-date view of the UPnP network. The RADA finds information about remote UPnP devices and services by synchronizing with remote RADAs.
The main purpose in maintaining this aggregate view of available devices, is to alleviate the timing dependencies inherent in the UPnP Discovery mechanism. When a UPnP Control Point issues a search request, the request packet contains a parameter that specifies the maximum number of seconds a device can wait before sending the response. In remote scenarios, it is possible that this value will be exceeded with normal network traffic delay.
This aggregate view also serves to minimize the amount of SSDP traffic that needs to flow across the remote transport, as some remote scenarios may be cost-sensitive in regards to the amount of data that is transferred, since SSDP is often described as a "chatty" protocol.
The aggregate view could be used to restrict the visibility of local UPnP devices and services from remote devices and of UPnP devices and services hosted by remote devices to your local network.
This service does not address the actual transport protocol used to facilitate Remote Access.
The RADASync service is a UPnP service that provides control points with the following functionality:
• Publish and remove information about the existence of remote devices.
• Notification of the availability of the peer RADA.
• Register RADASync service that is co-located with the control point
This service does not address:
• Aggregation of the the local view of the UPnP network.
• Relaying discovery messages in the local network on behalf of remote devices
• Configuration of which devices are visible to and from a remote network.
• Transport protocol used to facilitate Remote Access or its configurtion.