COM development |
| Friday, 28 March 2008 02:26 | |||
|
COM (Component Object Model) development is something that takes time to understand. I spent many hours reading about how COM works and how to program with it. I thought it was fun to create applications that integrate very closely with Word and IE. The ability to abstract methods of execution on multiple machines using IUnknown is great. DCOM and COM were a beast to learn however. There are many levels of abstractions to learn about. All of a sudden we are talking about contracts in IDL, querying for interfaces, registering controls, reference counting, threading apartment models, etc. It all takes time to grok. COM taught me to program to the interface. One usually wants to abstract out portions of their program to run on different machines or on the same machine across threads. These interfaces can be exposed to scripting languages like VBScript, JScript to allow for easy composition of functionality. COM is powerful and efficient at times. .NET managed code and the CLR have negated the need for much of it however. It was something that was promised as cross platform, without an implementation and looks to be going out the door?! Microsoft kills more third-party ActiveX controls This makes sense, but it is a bit strange that a technology is being used to filter out malware....an a corp. has the power to sent a kill bit at anytime. COM MaintenanceApparently there were some pretty serious security holes in ATL. Do you know that your ActiveX/COM assets are safe? Make sure to read the literature and patch accordingly!Microsoft Security Bulletin MS09-035 - Moderate: Vulnerabilities in Visual Studio Active Template Library Could Allow Remote Code Execution (969706) ATL Security Update July 28 2009, Microsoft announced that ATL was impacted in Security Advisory (973882) and provided updated versions of ATL with the release of security bulletin MS09-035. You can build COM components from all sorts of languages. MFC, VB, C#, Python, PHP, Perl, etc. The best way to create native COM controls is to write them using C++ ATL. The executables are small, fast, and easy to deploy. You can create and consume COM components from managed code as well. Some of the things you can do because of COM...Automate word/excel/access/etc to perform basically any action within the application as well as close access to the object model exposed. Also, have the ability to receive events as the user performs actions. Create new UI within IE using ActiveX. ActiveX is trusted native code, so you can really do anything your little heart desires. ISAPI filters for internet information server (MS's webserver). Extend windows explorer to add additional menu items. Custom applications of course. ActiveX does not own it's own MessageLoopMessages are pushed to it from the container, so one work around is to create a message hook.The TAB key, arrow keys, and accelerator keys do not work as expected when an ActiveX control is the parent window of a modeless dialog box or of a propertysheet window Windows Template Library - WTLWhen writing native COM controls, I think adding WTL is very important to gain strong UI capabilities. WTL is a set of C++ template libraries which extend the ATL templates with rich UI control. I've written and seen some very cool UI with WTL.SourceForge.net: Windows Template Library (WTL) CodeProject: WTL Class for ActiveX Hosting. Unwound Stack » How does WTL connect HWNDs to C++ objects? COM future?Today, there are still somethings that are only done with COM. So until .NET replaces everything. There is still a real need for it.The comtypes package - The comtypes python package makes it easy to access and implement both custom and dispatch based COM interfaces. Active Template Library - ATLCodeProject: ATL/AUX Library. - great article and code.CodeProject: ATL - the whole ATL section in codeproject is priceless. daily blah: Practial advising with ATL BUGFIX: ATL's CWindowImpl crashes when OnFinalMessage contains code to destroy the class instance COM EventingAtlEvnt.exe sample shows how to creates ATL sinks by using the ATL IDispEventImpl and IDispEventSimpleImpl classesHow to sink HTML document events for WebBrowser host - syncs DWebBrowserEvents2 for DocumentComplete and then syncs to the documents HtmlDocumentEvents signcode without password / signcode don't prompt passwordIf you are writing certain types of COM controls (IE activex controls), you will need to sign your code with a signing key. To sign you'll use signcode, but signcode doesn't allow you to pass a password argument. Instead, use signtool.exe which comes part of VS2005 and within the (Platform SDK/Windows SDK). If you are using the Windows SDK, when I installed it was in "C:\Program Files\Microsoft SDKs\Windows\v6.1\Bin". It does allow you to specify the private key password on the command line. This is useful for automating a signed build.Code Signing for Developers Code Signing - more overview of signing stuff. Download details: Office 2000 Tool: PVK Digital Certificate Files Importer - includes pvkimprt tool P4 Tasks » Problems and Solutions installing pvkimprt.exe Shell programmingWindows® API Code Pack for Microsoft® .NET Framework (v0.85) - Home - interesting, stuff you could only do with COM in managed code! Support for Windows Shell namespace objects, including the new Windows 7 libraries, Known Folders and non file system containers, Windows 7 Explorer Browser Control supporting both WPF and Windows Forms, Support for Shell property system.BITS - Background Intelligent Transfer Servicedaily blah: Background Intelligent Transfer ServiceMoserware: Finally Understanding COM After Changing a Light Bulb Moserware: Using Obscure Windows COM APIs in .NET Dependency Walker (depends.exe) Home Page - this tool has been invaluable to me. It tells you all the files required for a binary. (ocx,dll,exe,etc) Jer's One Stop Shop > Home - Silverlight 4 Hack: Use Native/Desktop CLR Without COM Registration COM for the “I did C++ once a thousand years ago, but only do .NET now” Developer –or– In the Defense of COM « Jer's Hacks
|
|||
| Last Updated on Tuesday, 22 November 2011 09:17 |