Essential IDL

The core language of Microsoft's Component Object Model (COM), Interface Definition Language (IDL), is an essential topic for all programmers working with COM. Essential IDL offers these programmers a detailed yet accessible description of IDL and its application to COM development projects. The book presents all of the various IDL constructs and offers insight into their purpose and function in interface definitions. In particular, Essential IDL focuses on IDL constructs that support the efficient marshalling of data as performed by the COM interception layer. Taking a top-down approach, this book opens with the basics of defining interfaces and then details data types, pointers and arrays, aliasing, and IDL support for asynchronous COM. Numerous examples of both server-side and client-side programming illustrate concepts and techniques throughout the book. Readers will learn about such key topics as:

• Generating type information
• Building proxy-stub DLLs
• Local and remote interfaces
• Primitive, enumerated, and user-defined data types
• Interface inheritance
• Top-level versus embedded pointers
• Object references and pointers
• Fixed arrays, conformant arrays, and SAFEARRAYS
• Multi-dimensional conformant pointers
• Method and type aliasing
• Asynchronous calls
• Client-side and server-side asynchrony

Also included is a comprehensive and concise reference to IDL built-in data types, modifiers, keywords, and attributes. This combination of comprehensive description, understandable explanation, convenient reference, and practical working guide makes Essential IDL an important resource for all COM programmers.

ContentsHello, IDL
What is IDL?
Defining interfaces
Adding parameters
More on directionality
Conclusions

Structure of an IDL File
Interfaces and type information
Inside the library block
Versioning type libraries
Producing C++ type information
Outside the library block
Building a proxy-stub DLL
Interface definitions, type libraries and the oleautomation attribute
The local attribute
Importing other files
Importing files in the library block
Coclasses
Conclusions

Data Types and Interface Issues
Primitive data types
signed and unsigned data types
char vs byte
char vs wchar_t
LPOLESTR vs BSTR
Enumerated types
Object references
Structures
Unions
The VARIANT
Typedefs
Properties
Interface inheritance
Dispatch interfaces
Conclusions

Pointers and Arrays
Pointer basics
Pointers and const
Pointer semantics
Top-level vs embedded pointers
Pointers and language mappings
Object references and pointers
Arrays
Fixed size arrays
Conformant arrays
Conformant pointers
Conformant pointers as output parameters
Simulating fixed size arrays using conformance
Multi-dimensional conformant pointers
Arrays as structure members
Jagged arrays
SAFEARRAYs
Conclusions

Aliasing
Method aliasing
Type aliasing
More type aliasing
Conclusions

Asynchronous COM
Asynchronous calls
Client-side asynchrony
Server-side asynchrony
Conclusions