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 that is received 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. When the user input specifies no mapping of the interface parameters to the routine parameters of the called routine, the metadata establishes a mapping according to a default set of rules.