document: The interoperability of learning object repositories and services : standards , implementations and lessons learned Interoperability is one of the main issues in creating a networked system of repositories . The eduSource project in its holisticapproach to building a network of learning object repositories in Canada is implementing an open network for learning services . Itsopenness is supported by a communication protocol called theeduSource Communications Layer ( ECL ) which closely implements the IMS Digital Repository Interoperability ( DRI ) specification and architecture . The ECL in conjunction withconnection middleware enables any service providers to join thenetwork . EduSource is open to external initiatives as it explicitlysupports an extensible bridging mechanism between eduSource and other major initiatives . This paper discusses interoperability in general and then focuses on the design of ECL as animplementation of IMS DRI with supporting infrastructure andmiddleware . The eduSource implementation is in the mature stateof its development as being deployed in different settings withdifferent partners . Two applications used in evaluating ourapproach are described : a gateway for connecting betweeneduSource and the NSDL initiative , and a federated searchconnecting eduSource , EdNA and SMETE .
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