1. Distributed Application Communication using WCF Client 1 Madhan Sundaram , Piotr A. Zolnierczuk and Richard A. Riedel ORNL, USA Subscriber Host Client 2 Subscriber Introduction Publish Subscribe Publisher Client 3 Subscriber SNS slow controls data acquisition suite currently uses National Instrument’s Data Sockets for communication between distributed applications. Apart from NI dropping its support to Data Sockets, there were several challenges the DAS team had to overcome in order to effectively use this protocol. One of the main challenge was the values in Data Sockets were persistent i.e. whenever GetValue function was executed the last value set was returned making change detection difficult. To overcome these and to take advantage of latest Microsoft's .NET technologies, a new distributed application communication protocol was designed using Windows Communication Foundation (WCF). WCF employs contract based interface programming techniques. The service host and the client can be developed independently based on the contract interface. Two way event based communication is achieved using callback features in WCF. NetTCP binding employs binary transaction mode providing speed Subscription Event Notification Architecture Advantages WCF Provides single, unified and extendable programming object model that can be used to interact with no. of previously diverse distributed technologies • WCF offers easy way of implementing Publish-Subscribe scenario • Different protocols like basicHttp, NetTcp, SOAP etc., can be implemented • Event based communication is possible • Considerably reduces development time • Eliminates dependency on 3rd party libraries • Works seamlessly with other .NET aware languages Proof of Concept SNSUdp Host C# Client Web Browser Http NetTcp LabVIEW Labview Client Event Broadcast Satellite App ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.