Q174653: How to Call CoGetClassObjectFromURL() in an MFC App
Article: Q174653
Product(s): Microsoft C Compiler
Version(s): 4.0,4.01,5.0,6.0
Operating System(s):
Keyword(s): kbfile kbVC500 kbVC600
Last Modified: 03-JUL-2002
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The information in this article applies to:
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0
- Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
- Microsoft Internet Explorer (Programming) versions 4.0, 4.01
- Microsoft Windows Internet Services (WinInet)
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SUMMARY
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This Urlobj.exe sample demonstrates how to call the CoGetClassObjectFromURL()
function to download, register, and instantiate an object. The sample implements
two interfaces necessary to allow the CoGetClassObjectFromURL() function to work
properly: IBindStatusCallback and IWindowForBindingUI.
MORE INFORMATION
================
The following files are available for download from the Microsoft Download
Center:
Visual C++ 6.0:
DownloadDownload Urlobj.exe now
(http://download.microsoft.com/download/vc50pro/File/1/NT4/EN-US/Urlobj.exe)
For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored on secure servers that prevent any unauthorized
changes to the file.
Visual C++ .NET:
DownloadDownload Urlobjvcnet.exe now
(http://download.microsoft.com/download/visualstudionet/sample/1.26/win98mexp/en-us/Urlobjvcnet.exe)
Release Date: 2-Jul-2002
For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored on secure servers that prevent any unauthorized
changes to the file.
The CoGetClassObjectFromURL() function returns a class factory object for a given
CLSID. If the desired object is installed on the system, it is instantiated.
Otherwise, the necessary code is downloaded and installed from the specified
URL. The sample uses a CFormView to get the value of the CLSID, the URL pointing
to the code for the ActiveX object, the major and minor version, and the size of
the object for displaying (it assumes that the control will display itself in
some manner).
The bulk of the relevant code is found in the OnButton1() handler, which starts
the download process, and the OnStopBind() handler, which handles creating the
object after it has finished downloading.
The IBindStatusCallback and IWindowForBindingUI interfaces are implemented in the
file Download.cpp by using a CCmdTarget derived class and the MFC interface map
macros.
After the CoGetClassObjectFromURL() has completed the asynchronous download, the
OnStopBind() handler is called to display the control. In this handler the
sample demonstrates instantiating the actual object by using the
CWnd::CreateControl() function. This is assuming that the object is an OLE
control. The handler also contains some code that has been commented out that
demonstrates calling IClassFactory::CreateInstance() in the case that the object
is not an OLE control.
To maintain simplicity, the sample does not implement much error checking or
verification of user input.
Additional query words: softlib
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Keywords : kbfile kbVC500 kbVC600
Technology : kbVCsearch kbIEsearch kbAudDeveloper kbSDKIESearch kbSDKIE400 kbSDKIE401 kbVC500 kbVC600 kbVC32bitSearch kbVC500Search
Version : :4.0,4.01,5.0,6.0
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