3.1.1.5.8 IUnknown Interface
The IUnknown interface enables clients to retrieve pointers to other interfaces on a given object through the QueryInterface method, and to manage the existence of the object through the IUnknown::AddRef and IUnknown::Release methods. All other COM interfaces are inherited, directly or indirectly, from IUnknown. Therefore, the three methods in IUnknown reserve opnums 0 through 2, inclusive, for every interface.
The IUnknown interface has the local IDL attribute (section 2.2.27).
The UUID for this interface is {00000000-0000-0000-C000-000000000046}.
Methods in RPC Opnum Order
Method |
Description |
---|---|
Opnum0NotUsedOnWire |
QueryInterface Reserved for local use. Opnum: 0 |
Opnum1NotUsedOnWire |
AddRef Reserved for local use. Opnum: 1 |
Opnum2NotUsedOnWire |
Release Reserved for local use. Opnum: 2 |
In the preceding table, the term "Reserved for local use" means that the client MUST NOT send the opnum, and the server behavior is undefined<50> since it does not affect interoperability.
All methods MUST NOT throw exceptions.