IMcastAddressAllocation interface (mdhcp.h)

[Rendezvous IP Telephony Conferencing controls and interfaces are not available for use in Windows Vista, Windows Server 2008, and subsequent versions of the operating system. The RTC Client API provides similar functionality.]

IMcastAddressAllocation is the main interface for multicast address allocation. An application calls the COM CoCreateInstance function on this interface to create the multicast client interface object.

Inheritance

The IMcastAddressAllocation interface inherits from the IDispatch interface. IMcastAddressAllocation also has these types of members:

Methods

The IMcastAddressAllocation interface has these methods.

IMcastAddressAllocation::CreateLeaseInfo The CreateLeaseInfo method creates a lease information object for a subsequent call to RenewAddress or ReleaseAddress.
IMcastAddressAllocation::CreateLeaseInfoFromVariant The CreateLeaseInfoFromVariant method creates a lease information object for a subsequent call to RenewAddress or ReleaseAddress. This method is similar to CreateLeaseInfo but is used by Automation client languages such as Visual Basic.
IMcastAddressAllocation::EnumerateScopes The EnumerateScopes method creates an enumeration of multicast scopes available. This method is primarily for C++ programmers. Visual Basic and other scripting languages use get_Scopes instead.
IMcastAddressAllocation::get_Scopes The get_Scopes method creates a collection of IMcast scopes available. This method is similar to EnumerateScopes, but is used by scripting languages such as Visual Basic.
IMcastAddressAllocation::ReleaseAddress The ReleaseAddress method releases a lease that was obtained previously.
IMcastAddressAllocation::RenewAddress The RenewAddress method renews an address lease. Call CreateLeaseInfo to specify the parameters of the renewal request, and then call this method to make the request.
IMcastAddressAllocation::RequestAddress The RequestAddress method obtains a new lease for one or more multicast addresses. The EnumerateScopes or get_Scopes method must be called first.

Remarks

The multicast COM interfaces allow access to the network's facility for allocating, renewing, and releasing leases on multicast addresses. They encapsulate a set of function and data structure definitions. The COM interfaces free the programmer from the burden of understanding and manipulating these data structures. Moreover, because TAPI 3 itself is COM-based, these interfaces make multicast address allocation accessible in a way that is consistent with the other facilities provided by TAPI 3. Applications written using Visual Basic, Java, or scripting languages must use these COM interfaces—they cannot normally access the Windows API directly.

In addition, this component provides seamless and transparent support for local address allocation for non-multicast environments. The DWORD registry value HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\MCAST\LocalAllocation, when set to a nonzero value, specifies that random number generation performed on the local machine is to be used for the allocation of all multicast addresses. This allows applications to function the same way on a network without a multicast address allocation server as they would on a network with a multicast address allocation server. If the registry value is set to zero or does not exist, this component performs normally as described in the rest of this specification. Note that local address allocation is never used unless this registry key is set to a nonzero value; local address allocation is not a fallback mechanism for a temporarily inaccessible multicast address allocation server.

Multicast address allocation is currently the subject of an IETF working group. To access current information, query on "Internet draft" and "MDHCP" or "MADCAP" using any Internet search engine. In addition to MADCAP (previously called MDHCP), the proposed architecture includes a protocol for server-to-server coordination within a domain or AS, as well as a protocol for interdomain coordination. While this architecture is currently evolving, the client need not concern itself with the details of this scheme.

This component currently supports only IP version 4 addresses.

Requirements

Requirement	Value
Target Platform	Windows
Header	mdhcp.h

See also

IDispatch

IMcastLeaseInfo

IMcastScope