A tie is a concept to bind a class skeleton

Class skeleton

-As pattern:A class skeleton is an outline of a class that is used in software engineering. It contains a description of the class's roles, and describes the purposes of the variables and methods, but does not implement them...

 to an implementing class.
With this approach the class which should be invoked by a remote call, can be derived from a non-remoting class.
Usually a tie class is used in middleware

Middleware

Middleware is computer software that connects software components or people and their applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact...

systems, to perform delegation from the skeleton to an implementing class.

Example

Usually:

    Stub -remote-> Skeleton (perform logic)

Tie Approach:

    Stub -remote-> Tie Skeleton -delegate-> Class (perform logic)