• <ins id="pjuwb"></ins>
    <blockquote id="pjuwb"><pre id="pjuwb"></pre></blockquote>
    <noscript id="pjuwb"></noscript>
          <sup id="pjuwb"><pre id="pjuwb"></pre></sup>
            <dd id="pjuwb"></dd>
            <abbr id="pjuwb"></abbr>
            隨筆 - 42  文章 - 3  trackbacks - 0
            <2012年3月>
            26272829123
            45678910
            11121314151617
            18192021222324
            25262728293031
            1234567

            常用鏈接

            留言簿(2)

            隨筆檔案

            文章檔案

            網(wǎng)頁收藏

            搜索

            •  

            最新評(píng)論

            閱讀排行榜

            評(píng)論排行榜

            Recently, I have read Inside COM, it is not my first time to read it. But still I got some useful information from it.

            First of all, rather than inheriting, Containment and Aggregation are the two methods COM used to achieve reusability.
            Aggregation is the specialized form of Containment, in which the programmer doesn’t have to implement code in the outer component to forward/delegate a call to the inner component and hence makes the life of a programmer easier. In Aggregation, the outer component hands over the control of the interface, which is being implemented by the inner component, to the client directly and the outer component gets out of the picture. In Aggregation, the interface to the inner component is exposed directly to the client, which is in contrast with the Containment. The outer IUnknown and the Inner IUnknown will be having the different implementation of the QueryInterface and hence it violates the basic QueryInterface rules. To forward/delegate calls to the outer IUnknown, the inner component needs the outer component’s IUnknown interface pointer. The outer component passes its IUnknown interface pointer at the time of creating the inner component. The outer component calls CoCreateInstance and passes its IUnknown pointer in the second argument of CoCreateInstance. If this parameter is non-NULL, then the component is being aggregated, otherwise the component is not aggregated.

            Secondly, The IDispatch interface was initially designed to support Automation. It provides a late-binding mechanism to access and retrieve information about an object's methods and properties.In addition to the methods inherited from IUnknown, server developers must implement the following methods within the class definition of each object that is exposed:
            • GetTypeInfoCount returns the number of type descriptions for the object. For objects that support IDispatch, the type information count is always one.
            • GetTypeInfo retrieves a description of the object's programmable interface.
            • GetIDsOfNames maps the name of a method or property to a DISPID, which is later used to invoke the method or property.
            • Invoke calls one of the object's methods, or gets or sets one of its properties.

            When the client need to call the method provide by the server, and the code is like this:

             

             1HRESULT hret=CoInitialize(NULL); assert(SUCCEEDED(hret));
             2    CComPtr<IDispatch> ptr;
             3
             4    ptr.CoCreateInstance(L"InternetExplorer.Application");
             5      if(ptr==0{ wprintf(L"Unable to create Application\n"); return 1; }
             6    
             7    wchar_t *array=L"GoHome";
             9    long id;
            10    hret=ptr->GetIDsOfNames(IID_NULL,&array,1,LOCALE_SYSTEM_DEFAULT,&id);
            11    assert(SUCCEEDED(hret));
            12    
            13    DISPPARAMS noparams;  memset(&noparams,0,sizeof(noparams));
            14    
            15    hret=ptr->Invoke(id,IID_NULL,LOCALE_SYSTEM_DEFAULT,DISPATCH_METHOD,&noparams,NULL,NULL,NULL);   
            18    CoUninitialize();    return 0;
            19

            Third, Connection Points, Com’s Observer Pattern
            -Based on Callbacks
            -COM-Object can have one or more event sources
            -Per event source may be one or more subscribed event sink
            -asynchronous communication between a server and its clients

            //Client
            class myEventSink : public EventSink
            {
             void handleEvent(int arg)
             { cout << “myEventHandler” << arg << endl; }
            };

            //Server
            [ object, uuid(…) }
            interface IEventSource : IUnknown
            {
             HRESULT Attach( [in] IEventSink* PEveSink);
            };

            Protocol
            IConnectionPointContainer::FindConnectionPoint
            IConnectionPoint::Advise       //passing sink interface pointer, receiving cookie
            IConnectionPoint::Unadvice    //terminates notification

             

            posted on 2012-03-04 22:08 鷹擊長空 閱讀(1238) 評(píng)論(0)  編輯 收藏 引用

            只有注冊(cè)用戶登錄后才能發(fā)表評(píng)論。
            網(wǎng)站導(dǎo)航: 博客園   IT新聞   BlogJava   博問   Chat2DB   管理


            国产精品久久久久久| 久久久老熟女一区二区三区| 国产精品视频久久久| 好属妞这里只有精品久久| 亚洲国产成人久久综合野外| 亚洲AV日韩精品久久久久久久| 久久免费精品视频| 成人午夜精品无码区久久| 国产激情久久久久影院| 午夜天堂av天堂久久久| 久久综合久久综合九色| 久久综合鬼色88久久精品综合自在自线噜噜 | 少妇人妻综合久久中文字幕| 欧美亚洲国产精品久久蜜芽| 久久久久久久久久免免费精品| 99久久超碰中文字幕伊人| 日日狠狠久久偷偷色综合免费 | 中文精品久久久久人妻不卡| 久久99精品国产99久久6男男| 久久久久久一区国产精品| 久久久亚洲欧洲日产国码二区| 精品乱码久久久久久夜夜嗨| 久久国产免费观看精品| 99久久国产宗和精品1上映| 久久久久99精品成人片三人毛片 | AV狠狠色丁香婷婷综合久久| 亚洲国产精品无码久久久久久曰 | 日日狠狠久久偷偷色综合0| 中文字幕一区二区三区久久网站| 精品久久久久久亚洲| 色综合久久无码中文字幕| 色狠狠久久综合网| 亚洲国产成人久久综合野外| 久久久精品久久久久久 | 久久av无码专区亚洲av桃花岛| 无码8090精品久久一区| 久久精品国产一区二区三区| 丁香五月综合久久激情| 国产激情久久久久影院小草| 久久美女人爽女人爽| 精品水蜜桃久久久久久久|