• <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
            <2025年7月>
            293012345
            6789101112
            13141516171819
            20212223242526
            272829303112
            3456789

            常用鏈接

            留言簿(2)

            隨筆檔案

            文章檔案

            網(wǎng)頁(yè)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(zhǎng)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(wèn)   Chat2DB   管理


            久久精品国产精品亚洲精品| 亚洲欧美伊人久久综合一区二区| 久久久久无码精品国产不卡| 国产精品欧美久久久天天影视| 99久久精品国产一区二区| 亚洲人成无码网站久久99热国产| 婷婷综合久久中文字幕蜜桃三电影| 国产成人久久精品麻豆一区| 欧美丰满熟妇BBB久久久| 久久精品国产欧美日韩| 国产日产久久高清欧美一区| 久久精品国产免费观看三人同眠| 国产精品成人久久久久三级午夜电影 | 久久精品成人一区二区三区| 久久精品国产亚洲AV久| 亚洲国产精品成人久久蜜臀| 中文字幕亚洲综合久久2| 久久AV高清无码| 久久天天躁夜夜躁狠狠躁2022| 草草久久久无码国产专区| 久久不射电影网| 青青青青久久精品国产 | 狠狠色丁香久久婷婷综合图片| 久久天堂电影网| 欧美精品一本久久男人的天堂| 久久综合狠狠综合久久| 亚洲精品蜜桃久久久久久| 精品国产乱码久久久久久呢| 久久亚洲熟女cc98cm| 国产69精品久久久久久人妻精品| 亚洲国产成人精品女人久久久 | 色综合久久中文字幕无码| 亚洲国产一成人久久精品 | 久久嫩草影院免费看夜色| 久久精品无码一区二区日韩AV| 久久精品国产WWW456C0M| 国产精品日韩欧美久久综合| 国产一区二区精品久久凹凸| 久久久久97国产精华液好用吗| 日本精品久久久久久久久免费| 色99久久久久高潮综合影院|