What you will Learn Here…
1. Definition of ATL
2. ATL Features
3. Basic Definitions of ATL
4. ATL’s Component Class Hierarchy
5. FAQ
1. Definition of ATL
The Active Template Library (ATL) is a set of template-based C++ classes that allows to create small, fast Component Object Model (COM) objects.
2. ATL Features
1.ATL provides two types of wizards
a. AppWizard: AppWizard creates the initial ATL project.
b. Object Wizard: Object Wizard produces code for basic COM components.
2. Built-in support for basic COM functionality such as IUnknown, class factories, IDispatch (automation), dual interfaces and self-registration.
3. Inbuilt Support for Microsoft’s Interface Definition Language (IDL) which provides marshaling support for custom Vtable interfaces as well as component self-description through a type library.
4. Aggregation of objects and Automation support
5. Support for developing ActiveX controls.
3. Basic Definitions of ATL
1. Marshaling: Marshaling is the process of transferring function arguments and return values across process and machine boundaries.
2. The proxy/stub DLL implements standard marshaling for each of the component interfaces.
COM will use the IPC to communicate between client and server.
- LPC is used when both reside on the same machine.
- RPC is used in a distributed networked environment
4. ATL’s Component Class Hierarchy
ATL never Creates the instance of the CoClass Directly. Instead ATL uses CComObject template class with ‘CMathComp’ object type as a parameter
to create our Object.
CComObject * pMath = new ComObject
CComObjectRootEx – Handles object reference count management.
CComCoClass – Provides methods for creating instances of a class and obtaining its properties it has createInstance() method which creates the instance of a COM Object through ClassFactory
CComObject – Implements IUnknown for an COM object.
5. FAQ
1. What is ATL ?
check – 1. Definition of ATL
2. What is MIDL ?
check – 2. ATL Features – 3 point
3. What are the featurs of ATL ?
check – 2. ATL Feature
4. What is Marshiling ?
check – 3. Basic Definitions of ATL – 1 point
5. Explain about ATL’s Class Hierarchy?
check – 4.ATL’s Component Class Hierarchy
