The Concert signature representation

Abstract

In the Concert multilanguage distributed programming system, interface specification is the responsibility of programming languages, not a separate IDL. However, an IDL is still necessary in order to define equivalence between declarations in different languages. A single representation is also desirable internally to economize on aspects of the implementation. Consequently, Concert has an IDL as an intermediate language, produced by compiler front-ends and not normally manipulated by programmers. It is formally separated into a contract , which defines interoperability and an endpoint modifier , which captures the local choice of representation. Only contracts are used to define interface equivalence. Our choice of what kinds of information to put in the contract was motivated by a desire to be minimal, thereby enabling maximum feasible interoperability between different expressions of the same abstraction in the same or different languages.