I think I understand the issue. If you use COM aggregation, it is possible to have an object who's various interfaces are implemented by separate objects. But in that case the object doing the aggregating appears to the outside world as supporting all interfaces and so COM identity rules are maintained. Without using aggregation it's not easy to spread interfaces across multiple objects. I'd also argue that even with aggregation this is not common to any but those who are very well versed in COM. QueryService does not require aggregation and hence is easier to implement. A discussion of COM Object identity rules is at: http://msdn.microsoft.com/en-us/library/ms810016.aspx <blocked::http://msdn.microsoft.com/en-us/library/ms810016.aspx> Thanks, RG
_____ From: [email protected] [mailto:[email protected]] On Behalf Of Andres Gonzalez Sent: Wednesday, March 04, 2009 8:26 AM To: [email protected]; IA2 List Subject: Re: [Accessibility-ia2] Minutes for the Open Accessibility IA2 meeting - March 03, 2009 Pete and all: to clarify this note, I would explicitly say C++ object, where it says just object. The distinction is relevant because in COM literature, object is used also to refer to the entity that implements a group of interfaces, whether it consists of one or multiple C++ objects. The commonly used approaches to support QI using multiple C++ object are known as aggregation or containment. So it would read something like: . Andres informed us that you can use QI even when the implementation use two or more C++ objects. The reason for using QS from an IAccesible is due to MSAA's implementation on Windows and not something inherent in the COM architecture. MSAA always gives you a proxy which requires using QS to get to non-MSAA interfaces. A client will have to QS to IA2 but then QI can be used for all the other IA2 interfaces even if they are implemented on a separate C++ object. The proposed text for QS/QI will be updated to take this into consideration. --Andres. _____ From: [email protected] [mailto:[email protected]] On Behalf Of Pete Brunet Sent: Tuesday, March 03, 2009 6:56 PM To: IA2 List Subject: [Accessibility-ia2] Minutes for the Open Accessibility IA2 meeting - March 03, 2009 Please review the minutes for today's IA2 meeting at: http://www.linuxfoundation.org/en/Accessibility/IAccessible2/Minutes/2009030 3 -- Pete Brunet a11ysoft - Accessibility Architecture and Development (512) 238-6967 pete @ a11ysoft.com http://www.a11ysoft.com/about/ http://www.linkedin.com/in/petebrunet Ionosphere: WS4G
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