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Architecture

RTAI-XML provides a remoting approach to RT control applications design, based on XML abstraction layer. The aim of RTAI-XML is thus to obtain a structure like in the picture, where the Real-Time control process (the Target) and the user interaction related procedures (the Host) run independently, typically on two different CPUs, communicating over the network (Internet).

The structure

The problem to let a local procedure communicate with a remote one has been deeply investigated in the past years. Many Remote Procedure Call (RPC) strategies have been approached by the world leading software houses. Taking a look at the structure of the most known paradigms in this field, it is envisaged that the peer to peer approach sketched in the first picture has never been adopted. It has been normally preferred to add an abstraction layer, going towards a three- or multi- tiers approach.

The RTAI-XML approach, presented in the second picture, follows this general phylosophy. The core of the system is the RTAI-XML server that works as a bridge between the HRT and the SRT domains, allowing to instantiate a procedure from the SRT internet network to the HRT RT_NET network. From the internet side, RTAI-XML implements an RPC server based on XML; inside the RTAI domain, RTAI-XML connects directly to the target, using RT calls.

RTAI-Lab

RTAI-XML is strongly based on the RTAI-Lab project. The server-target communication has been completely inherited from this project and also the first functionalities implemented remind of those accessible through the XRTAI-Lab grafic interface. Having a practice with this tool will help in understanding the implementation of RTAI-XML.

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