3.1.4 Message Processing Events and Sequencing Rules

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This is an overview of the four methods used by the IDispatch interface. The names and opnums of each method follow, as well as a simple description of the method.

IDispatch derives from the IUnknown interface. IDispatch servers MUST implement the methods that are defined in IUnknown, in the order in which and with the opnums with which they are specified, in [MS-DCOM] Appendix A.

Methods in RPC Opnum Order

Method

Description

GetTypeInfoCount

The GetTypeInfoCount method specifies whether the automation server provides type description information.

Opnum: 3

GetTypeInfo

The GetTypeInfo method provides access to the type description information that is exposed by the automation server.

Opnum: 4

GetIDsOfNames

The GetIDsOfNames method maps a single member name (method or property name), and an optional set of argument names, to a corresponding set of integer DISPIDs, which can be used on subsequent calls to IDispatch::Invoke.

Opnum: 5

Invoke

The Invoke method provides access to properties and methods that are exposed by the automation server.

Opnum: 6

All methods MUST NOT throw exceptions. All return values use the NTSTATUS numbering space; in particular, a value of 0x00000000 indicates success, and any other return value indicates an error. All error values are specified in [MS-ERREF] and MUST be treated the same, unless specified otherwise.