RpcServerUseProtseqIfEx function (rpcdce.h)

The RpcServerUseProtseqIfEx function tells the RPC run-time library to use the specified protocol sequence combined with the endpoints in the interface specification for receiving remote procedure calls.


RPC_STATUS RpcServerUseProtseqIfEx(
  RPC_CSTR      Protseq,
  unsigned int  MaxCalls,
  void          *SecurityDescriptor,
  PRPC_POLICY   Policy



Pointer to a string identifier of the protocol sequence to register with the RPC run-time library.


Backlog queue length for the ncacn_ip_tcp protocol sequence. All other protocol sequences ignore this parameter. Use RPC_C_PROTSEQ_MAX_REQS_DEFAULT to specify the default value. See Remarks.


Interface containing endpoint information to use in creating a binding for the protocol sequence specified in the Protseq parameter.


Pointer to an optional parameter provided for the security subsystem. Used only for ncacn_np and ncalrpc protocol sequences. All other protocol sequences ignore this parameter. Using a security descriptor on the endpoint in order to make a server secure is not recommended. This parameter does not appear in the DCE specification for this API.


Pointer to the RPC_POLICY structure, which contains flags to restrict port allocation for dynamic ports and that allow multihomed computers to selectively bind to network interface cards.

Return value

Value Meaning
The call succeeded.
The endpoint for this protocol sequence is not specified in the IDL file.
The protocol sequence is not supported on this host.
The protocol sequence is invalid.
The endpoint format is invalid.
The system is out of memory.
The security descriptor is invalid.
Note  For a list of valid error codes, see RPC Return Values.


The parameters and effects of RpcServerUseProtseqIfEx extend those of RpcServerUseProtseqIf. The difference is the Policy parameter, which allows you to restrict port allocation for dynamic ports and allows multihomed computers to selectively bind to network interface cards.

Setting the NICFlags field of the RPC_POLICY structure to 0 makes this extended API functionally equivalent to the original RpcServerUseProtseqIf, and the server will bind to NICs based on the settings in the system registry. For information on how the registry settings define the available Internet and intranet ports, see Configuring the Registry for Port Allocations and Selective Binding.

Note  The flag settings in the Policy field are effective only when the ncacn_ip_tcp or ncadg_ip_udp protocol sequence is in use; for all other protocol sequences, the RPC run time ignores these values.
A server application calls RpcServerUseProtseqIfEx to register one protocol sequence with the RPC run-time library. With each protocol-sequence registration, the routine includes the endpoint-address information provided in the IDL file.

To receive remote procedure call requests, a server must register at least one protocol sequence with the RPC run-time library. A server application can call this routine multiple times to register additional protocol sequences.

For each protocol sequence registered by a server, the RPC run-time library creates one or more endpoints through which the server receives remote procedure call requests. The RPC run-time library creates different endpoints for each protocol sequence. However, each interface in the process is accessible through any endpoint. For more information, see Writing a Secure RPC Client or Server.

For MaxCalls, the value provided by the application is only a hint. The RPC run time or the Windows Sockets provider may override the value. For example, on Windows XP or Windows 2000 Professional, the value is limited to 5. Values greater than 5 are ignored and 5 is used instead. On Windows Server 2003 and Windows 2000 Server, the value will be honored.

Applications must be careful to pass reasonable values in MaxCalls. Large values on Server, Advanced Server, or Datacenter Server can cause a large amount of non-paged pool memory to be used. Using too small a value is also unfavorable, as it may result in TCP SYN packets being met by TCP RST from the server if the backlog queue gets exhausted. An application developer should balance memory footprint versus scalability requirements when determining the proper value for MaxCalls.

When the computer is configured to use selective binding, successful return does not guarantee that the server has created endpoints for all the network interfaces present on the computer. The RPC run-time may not listen on some network interfaces depending on the selective binding settings. In addition, if an interface has not yet received an IP address using DHCP, the RPC server does not listen on the network interface until a DHCP address is assigned to it. A successful return implies that the server is listening on at least one network interface; the full list of the binding handles over which remote procedure calls can be received can be obtained with a call to the RpcServerInqBindings function.

To register all protocol sequences from the IDL file, a server calls RpcServerUseAllProtseqsIfEx. For more information, see Server-Side Binding. For a list of Microsoft RPC supported protocol sequences, see String Binding.


Minimum supported client Windows XP [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Target Platform Windows
Header rpcdce.h (include Rpc.h)
Library Rpcrt4.lib
DLL Rpcrt4.dll

See also





Writing a Secure RPC Client or Server