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A URL moniker is a system-provided moniker class that supports asynchronous binding to a Uniform Resource Locator (URL). This section covers the moniker functionality exported by the Urlmon.dll dynamic-link library (DLL).
This documentation assumes that you have an understanding of Microsoft® Win32® programming and an understanding of OLE and COM programming. For the Internet-related interfaces, methods, and functions, an understanding of the format and syntax of URLs is also required. For more information, see RFC 1738, Uniform Resource Locators (URL). You can find this document at ftp://ftp.isi.edu/in-notes/rfc1738.txt. 
To compile programs that use the URL monikers, you must make sure the Urlmon.h header file is in the include directory, and the Urlmon.lib library file is in the library directory, of the C/C++ compiler you use.
A Uniform Resource Locator (URL) follows the syntax described in RFC 1738, which specifies a protocol scheme followed by a scheme-specific portion (<scheme>:<scheme-specific portion>). For example, in the URL http://www.microsoft.com/, "http" is the scheme and "//www.microsoft.com/" is the scheme-specific portion.
The beginning part of the scheme-specific portion of the URL contains the server name. This portion of the URL is often referred to as the URL namespace.
Monikers are used as the basis for linking in OLE. After a moniker is bound to an object, the moniker's IMoniker interface can be used to locate, activate, and access the bound object without having any other specific information on where the actual object is located. For standard monikers, this binding process occurs synchronously, which does not impact performance dramatically because the moniker and object are usually on a local system. Examples of objects that can be bound to a moniker include files, items, and pointers.
Binding a moniker to a URL synchronously impacts performance because the process has to wait for responses from the network before completing the binding process. That is where asynchronous URL monikers and the URL functions come in.
Interfaces related to URL monikers
Functions related to URL monikers
The URL functions combine the capabilities of asynchronous monikers and URL monikers into easy-to-use functions.
URL functions
Follow these steps to create a URL moniker for an application:
Warning The size of the BINDINFO structure used by IBindStatusCallback::GetBindInfo has changed in Microsoft® Internet Explorer 4.0 and later. Developers must write code that checks the size of the BINDINFO structure that is passed into their implementation of the IBindStatusCallback::GetBindInfo method before writing to members of the structure. For more information, see the Handling BINDINFO Structures section.
Follow these steps to create a URL moniker for a control:
Warning The size of the BINDINFO structure used by IBindStatusCallback::GetBindInfo has changed in Internet Explorer 4.0 and later. Developers must write code that checks the size of the BINDINFO structure that is passed into their implementation of the IBindStatusCallback::GetBindInfo method before writing to members of the structure. For more information, see the Handling BINDINFO Structures section.
Note MSHTML does not support the IBindStatusCallback interface. Applications that are hosting MSHTML and want to get callbacks on the progress of the bind operation should implement the IPropertyNotifySink interface.
The BINDINFO structure is used by methods, such as IBindStatusCallback::GetBindInfo, to pass information that specifies how a bind operation should be handled. To properly write information to this structure, the client application should:
Clearing the BINDINFO structure, before writing information into it, prevents members that are not being used from containing incorrect data. The following code fragment demonstrates how to clear the structure.
// pbindinfo is a pointer to a BINDINFO structure. DWORD cbSize = pbindinfo->cbSize; memset(pbindinfo,0,cbSize); pbindinfo->cbSize = cbSize;
Because the size of the BINDINFO structure has increased in Internet Explorer 4.0 and later, client applications should check the size of the structure that is passed into their implementation of any methods that use this structure.
The following sample demonstrates how to check the size of the structure for accessing members of the BINDINFO structure beyond cbstgmedData.
if (pbindinfo->cbSize >= offsetof(BINDINFO, dwReserved))
{
// Write to additional fields.
}
else
{
// Added functionality is not available, so make any adjustments necessary.
}
The URLDownloadToCacheFile, URLDownloadToFile, URLOpenBlockingStream, URLOpenPullStream, and URLOpenStream functions combine the capabilities of asynchronous monikers and URL monikers into easy-to-use functions.
The following sample demonstrates how to use the URLOpenBlockingStream function.
IStream* pStream;
char buffer[0x100];
DWORD dwGot;
HRESULT hr = NOERROR;
// Open a blocking type stream to the Web site stored in the
// string szWebSite.
URLOpenBlockingStream( 0, szWebSite, &pStream, 0, 0);
do {
hr = pStream->Read( buffer, sizeof(buffer), &dwGot );
// Do something with contents of buffer.
} while( SUCCEEDED(hr) && hr != S_FALSE);
return TRUE;
pStream->Release();
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