wrapper
A software component that encapsulates a system component (a procedure, a program, a file, an API) in order to transform its interface with its environment. For instance, a wrapper associated with a legacy program can give the latter an object-oriented interface.
In a database setting, a data wrapper is a software component that encapsulates a database or a set of files in order to change its model and the API through which the data can be manipulated. For example, a data wrapper built on top of a standard file can allow application programs to access the contents of the file as if it were a relational table or a collection of XML documents.