RPC_ASYNC_STATE structure (rpcasync.h)
The RPC_ASYNC_STATE structure holds the state of an asynchronous remote procedure call. RPC_ASYNC_STATE is a handle to this structure, used to wait for, query, reply to, or cancel asynchronous calls.
Syntax
typedef struct _RPC_ASYNC_STATE {
unsigned int Size;
unsigned long Signature;
long Lock;
unsigned long Flags;
void *StubInfo;
void *UserInfo;
void *RuntimeInfo;
RPC_ASYNC_EVENT Event;
RPC_NOTIFICATION_TYPES NotificationType;
RPC_ASYNC_NOTIFICATION_INFO u;
LONG_PTR Reserved[4];
} RPC_ASYNC_STATE, *PRPC_ASYNC_STATE;
Members
Size
Size of this structure, in bytes. The environment sets this member when RpcAsyncInitializeHandle is called. Do not modify this member.
Signature
The run-time environment sets this member when RpcAsyncInitializeHandle is called. Do not modify this member.
Lock
The run-time environment sets this member when RpcAsyncInitializeHandle is called. Do not modify this member.
Flags
The flags member can be set to the following values.
| Constant | Meaning |
|---|---|
|
Posts a notification message when the asynchronous operation is complete. |
These flags are used with DCE pipes, which allow applications to send or receive data in multiple blocks. Programs can either send a continuous stream of data or wait for each block to be transmitted before it sends the next block. If it does not wait, the RPC run-time library will buffer the output until it can be sent. When the data transmission is complete, the RPC library sends the application a notification. If an application specifies the RPC_C_NOTIFY_ON_SEND_COMPLETE flag, the RPC library sends it a member of the RPC_NOTIFICATION_TYPES enumeration after it completes each send operation.
StubInfo
Reserved for use by the stubs. Do not use this member.
UserInfo
Use this member for any application-specific information that you want to keep track of in this structure.
RuntimeInfo
Reserved for use by the RPC run-time environment. Do not use this member.
Event
Type of event that occurred. The RPC run-time environment sets this field to a member of the RPC_ASYNC_EVENT enumeration.
NotificationType
Type of notification the RPC run time should use to notify the client for the occurrence of an event, such as completion of the call or completion of the event.
| Value | Meaning |
|---|---|
|
No notification is specified; RPC_ASYNC_NOTIFICATION_INFO is not initialized. |
|
The notification mechanism is a Windows event. |
|
The notification mechanism is a Windows asynchronous procedure call. |
|
The notification mechanism is an I/O completion port. |
|
The notification mechanism is a Windows system message.
Windows Server 2003 or later: Notification via the HWND is deprecated. Do not use this value. |
|
The notification mechanism is a function callback. |
u
Contains asynchronous notification information formatted for the mechanism type specified in NotificationType.
Reserved[4]
Reserved for compatibility with future versions, if any. Do not use this member.
Remarks
The client allocates space for the RPC_ASYNC_STATE structure and an associated handle, and calls RpcAsyncInitializeHandle to initialize the structure. After the run-time environment has successfully initialized the structure, the client initializes the NotificationType, and exactly one of the following structures in the RPC_ASYNC_NOTIFICATION_INFO union: APC for a Windows asynchronous procedure call, IOC for an I/O completion port, HWND for a Windows system message, or hEvent for a Windows event. If the chosen notification method is RpcNotificationTypeNone, no field of the union needs to be initialized. The RPC client may optionally initialize the UserInfo field as well.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Header | rpcasync.h (include Rpc.h) |