A method and apparatus for communicating between a called routine written in a first programming language and calling routine written in a second programming language is described. User input specifies an interface of a proxy routine and the interface parameters of the interface. Metadata that is generated establishes a mapping of interface parameters to the routine parameters of the called routine. At least one interface parameter is of a data type not supported in the first programming language. The user input may specify that a first attribute of a particular interface parameter is associated with a first routine parameter of the called routine, and a second attribute of the particular interface parameter is associated with a second routine parameter of the called routine. The metadata maps the first attribute to the first routine parameter, and the second attribute to the second routine parameter.