transmit_as

typedef [transmit_as(xmit-type) [ , type-attribute-list ] ]
    type-specifier declarator-list;

void __RPC_USER type-id_to_xmit (
    type-id __RPC_FAR *,
    xmit-type __RPC_FAR * __RPC_FAR *);

void __RPC_USER type-id_from_xmit (
    xmit-type __RPC_FAR *,
    type-id __RPC_FAR *);

void __RPC_USER type-id_free_inst (
    type-id __RPC_FAR *);

void __RPC_USER type-id_free_xmit (
    xmit-type__RPC_FAR *);

xmit-type: Specifies the data type that is transmitted between client and server.
type-attribute-list: Specifies one or more attributes that apply to the type. Valid type attributes include handle, switch_type; the pointer attribute ref, unique, or ptr; and the usage attributes string and ignore. Separate multiple attributes with commas.
type-specifier: Specifies a base_type, struct, union, enum type, or type identifier. An optional storage specification can precede type-specifier.
declarator-list: Specifies standard C declarators, such as identifiers, pointer declarators, and array declarators. For more information, see pointers and arrays. The declarator-list consists of one or more declarators separated by commas. The parameter declarator in the function declarator, such as the parameter name, is optional.
type-id: Specifies the name of the data type that is presented to the client and server applications.

Examples

typedef struct _TREE_NODE_TYPE { 
    unsigned short data; 
    struct _TREE_NODE_TYPE * left; 
    struct _TREE_NODE_TYPE * right; 
} TREE_NODE_TYPE; 
 
typedef [transmit_as(TREE_XMIT_TYPE)] TREE_NODE_TYPE * TREE_TYPE; 
 
void __RPC_USER TREE_TYPE_to_xmit( 
    TREE_TYPE __RPC_FAR * , 
    TREE_XMIT_TYPE __RPC_FAR * __RPC_FAR *); 
 
void __RPC_USER TREE_TYPE_from_xmit ( 
    TREE_XMIT_TYPE __RPC_FAR *, 
    TREE_TYPE __RPC_FAR *); 
 
void __RPC_USER TREE_TYPE_free_inst( 
    TREE_TYPE __RPC_FAR *); 
 
void __RPC_USER TREE_TYPE_free_xmit( 
    TREE_XMIT_TYPE __RPC_FAR *);

Remarks

The transmit_as attribute instructs the compiler to associate type-id, a presented type that client and server applications manipulate, with a transmitted type xmit-type. The user must supply routines that convert data between the presented and the transmitted types; these routines must also free memory used to hold the converted data. The transmit_as attribute instructs the stubs to call the user-supplied conversion routines.

The transmitted type xmit-type must resolve to a MIDL base type, predefined type, or a type identifier. For more information, see base_types.

The user must supply the following routines:

Routine name	Description
type-id_to_xmit	Converts data from the presented type to the transmitted type
type-id_from_xmit	Converts data from the transmitted type to the presented type
type-id_free_inst	Frees storage used by the callee for the presented type
type-id_free_xmit	Frees storage used by the caller for the transmitted type

The client stub calls type-id_to_xmit to allocate space for the transmitted type and to translate the data into objects of type xmit-type. The server stub allocates space for the original data type and calls type-id_from_xmit to translate the data from its transmitted type to the presented type.

Upon return from the application code, the server stub calls type-id_free_inst to deallocate the storage for type-id on the server side. The client stub calls type-id_free_xmit to deallocate the xmit-type storage on the client side.

The following types cannot have a transmit_as attribute:

Context handles (types with the context_handle type attribute and types that are used as parameters with the context_handle attribute)
Parameters that are conformant, varying, or open arrays
Structures that contain conformant arrays
The predefined type handle_t, void

When a pointer attribute appears as one of the type attributes with the transmit_as attribute, the pointer attribute is applied to the xmit_type parameter of the type-id-to_xmit and type-id-from_xmit routines.

transmit_as

Examples

Remarks

See Also