Page "Smalltalk" Paragraph 30

Another important use of is intercession.

One can create a class that does not define any methods other than and does not inherit from any other class.

The instances of this class effectively understand no messages.

So every time a message is sent to these instances they actually get sent, hence they intercede in the message sending process.

Such objects are called proxies.

By implementing appropriately, one can create distributed systems where proxies forward messages across a network to other Smalltalk systems ( a facility common in systems like CORBA, COM + and RMI but first pioneered in Smalltalk-80 in the 1980s ), and persistent systems where changes in state are written to a database and the like.

An example of this latter is Logic Arts ' VOSS ( Virtual Object Storage System ) available for VA Smalltalk under dual open source and commercial licensing.