MethodNode Use Cases|OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

There are essentially two use cases:

1) Well-known methods:

Several information models (like OPC UA for Devices, BACNET) specify methods with their in- and out-arguments. These methods are considered well-known and Clients that understand these information models will be able to use the methods without user interaction.

2) Generic clients:

Clients that want to be kept as generic as possible can build a user interface by reading the method definition in the server's address space.