Activex and Object Linking and Embedding(OLE)

Activex and Object Linking and Embedding(OLE)

1.What are the features supported by COM?

COM provides a unigfied expandable object oriented communications protocol for windows.

- A standard language independent way for a win32 client EXE to laod and call a win 32 DLL.

- A general purpose way for one EXE to control another EXE on the same computer.

- A replacement for the VBX control called an activex control.

2. What is the use of Iunknown interface?

Iunknown is a special interface to obtain the interface pointer declayed by COM.

3. What is class factory?

A class object is sometimes called as a class factory because it often implements a special COM interface named IclassFactory.

4.What is the use of CLSIDFromProgID?

COM supports other types of registration database entry that manufactures a human-readable program ID into the corresponding Class ID. The COM function USI form program ID reads the database and performs the manipulation.

5. What do the INTERFACE _PART macro do?

The INTERFACE_PART macro generate the nested classes, adding x to the first parameters to form the class name and adding m-x to form the embedded object name.

6.What is the purpose of the DECLARE_INTERFACE_MAP macro?

The DECLARE_INTERFACE_MAP macro generalizes the declarations for a table that holds the Ids of the class’s entire interface.

7.List out the four states that an embedded object can assume?

1. Passive

2. Loaded

3. Running

4. Active

8. What are the special features of the Container?

1. It handles multiple documents.

2. Maintains a temporal stprage.

3. Allows embedded objects to be copied and cut to the clipboard and pasted

4. Allows an embedded object to be deleted

9.Define COM.

The Component Object Model (COM) specifies architecture , a binary standard and a supporting infrastructure for building component based applications .

10. What is DCOM?

Distributed Component Object Model ( DCOM ) is the distributed extension of COM. It specifies the additional infrastructure that is required to further extend the benefits to networked environments.

11. What are the main features of COM?

The main features of COM are

- Seperation of interfaces and implementations.

- Support for objects with multiple interfaces

- Language neutrality

- Runtime binary software reuse

- Location transparency

12. Write short notes on Versioning?

COM’s approach to versioning is based on the following three requirements:

Any interface must be unmutable

A new oimplementation of same CLSID must support existing interface.

Any client must start interfacing with a server by querying an interface with an IID.

13. Define OLE?

OLE stands for Object Linking and Embedding . OLE is at the core of window applications . It is also a very complex technology that could be different to master without the help of MFC.

14. What are the applications of OLE?

- Compound documents

- OLE Controls

- OLE Automation

- OLE Drag and Drop

- Specialized MAPI

15. What is marshaling?

In a remote procedure call the client makes calls to proxy . The proxy sends a stream to a stub. When the client calls the component function , the proxy alerts the stub by sending the message to the component program. The mechanism of converting parameters to and from data streams is called marshalling.