Language is a Natural Key

The utility of federated systems is dependent upon communication between participating data systems. It is useful to think of this communication as existing at three levels. The lowest level represents the network connection between devices, encompassing the physical connection and network protocols such as TCP/IP. The 

Although any well-defined computer data format is potentially usable at this level, languages are particularly suitable for the highest level of communication in federated information systems. 

Data systems that participate in a federation can be very heterogeneous both in their content and implementation. In a federated system, it is a great advantage to define communication in terms of external abstraction rather than in terms of internal computer representation. This is not so true for unified systems, where the imposition of a specific data model among components makes it more reasonable to define communication in terms of computer-oriented characteristics and assumptions. 

Two communication languages used by Cabinet are SMILES and ECN (En2yme Commission Number). When one Cabinet server asks another, What do you know about Lipitor , it is asking about SMILES  

When asking, What do you know about hydroxy-methyl-glutaryl-CoA reductase. , it asks about the EC Number  

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