C++ COM ActiveX Interview Preparation Guide
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C++ COM ActiveX frequently Asked Questions by expert members with experience in C++ COM ActiveX. These questions and answers will help you strengthen your technical skills, prepare for the new job test and quickly revise the concepts

22 C++ COM ActiveX Questions and Answers:

1 :: What is Component Object Model?

COM defines an API to allow for the creation of components for use in integrating custom applications or to allow diverse components to interact.

But in order to interact, components must adhere to a binary structure specified by Microsoft.

As long as components adhere to this binary structure, components written in different languages can interoperate.

2 :: Tell me how does COM provide language transparency?

COM defines an API to allow for the creation of components for use in integrating custom applications or to allow diverse components to interact.

But in order to interact, components must adhere to a binary structure specified by Microsoft.

As long as components adhere to this binary structure, components written in different languages can interoperate.

3 :: Do you know what is a type library?

A file or component within another file that contains standard descriptions of exposed objects, properties, and methods

A type library contains a binary description of an interface exposed by a COM-component. In this sense, they contain the same information that is contained in an IDL (Interface Definition Language) file..

4 :: What is IUnknown interface?

The IUnknown interface lets clients get pointers to other interfaces on a given object through the QueryInterface method, and manage the existence of the object through the IUnknown::AddRef and IUnknown::Release methods.

IUnknown methods can be used to switch between interfaces on an object, add references, and release objects.
You must implement IUnknown as part of every interface.

5 :: What is STL, standard template library?

The Standard Template Library, or STL, is a C++ library of container classes, algorithms, and iterators; it provides many of the basic algorithms and data structures

The STL includes the classes vector, list, deque, set, multiset, map, multimap, hash_set, hash_multiset, hash_map, and hash_multimap.

6 :: What is OLE?

Object Linking and Embedding (OLE) is about using documents generated by one application inside another application.

7 :: What is ActiveX?

ActiveX is a Microsoft rebranding of OLE with more focus on smart Windows controls.

8 :: What is object serialization?

A serialized object represents the type of data stored in the object, its information. Object serialization is a process of reading or writing an entire object from a file. This helps in saving session state information by servlets, for sending parameters for Remote Method Invocation (RMI) calls.

9 :: What is Globally Unique Identifier?

A 16-byte number generated by Microsoft programs that uniquely identifies a network or user or computer or document. It is one of the elements of information that can be passed when you connect to an Internet site, and it may be stored in cookies

10 :: Why does COM need GUIDs?

A globally unique identifier (GUID) is used for unique IDs. No two GUIDs are the same no matter what computer they were generated on. The attribute clsid defines the GUID of the associated ActiveX control to use.