Inter-Language Unification or ILU is a multi-language object interface system. The object interfaces provided by ILU hide implementation distinctions between different languages, between different address spaces, and between operating system types. ILU can be used to build multi-lingual object-oriented libraries ("class libraries") with well-specified language-independent interfaces. It can also be used to implement distributed systems. It can also be used to define and document interfaces between the modules of non-distributed programs. ILU interfaces can be specified in either the Object Management Group's CORBA Interface Definition Language (OMG IDL), or ILU's Interface Specification Language (ISL).
ILU was developed as an Open Source project at the Xerox Palo Alto Research Center (Xerox PARC) from 1991 until 2000. The last release was 2.0beta1.
From 1997 to 2000, ILU was used as the foundation for experimental work on a "next generation" HTTP protocol by the World Wide We