64 bit Editions of Windows Evaluation Guide - Technology and Trends

� 64 bit Editions of Windows Evaluation Guide
64 bit Editions of Windows Environment
The 64 bit Editions of Windows development environment supports the same feature set as 32 bit
Windows. This includes user interface and programming models, networking, security, graphics,
multimedia, directory service, Plug and Play, and tools features. Many of the functions have been
modified to reflect the computational precision of the platform on which an application is run.
The result is simplicity and a short learning curve for the developer. Writing code for the 64 bit
Editions of Windows is just like writing code for 32 bit Windows. Developers can compile a single
source base to run natively on either Win32- or Win64-based systems. This strategy reduces the
cost of developing applications for the 64 bit architecture.
The 64 bit and 32 bit processes use their respective dynamic link libraries (dlls). However, the
COM clients and remote procedure calls (RPCs) from both environments can communicate with
each other.
General Porting Guidelines
Porting applications to the Windows XP 64 bit Edition will go smoothly with careful planning.
Microsoft has provided some general guidelines below to help with the migration.
Planning
Determine the magnitude of the effort required for the port. Gauge how much work is involved
by identifying the following items:
� Identify problem 32 bit code. Compile your 32 bit code with the 64 bit compiler and
examine the extent of the errors and warnings.
� Identify shared components or dependencies. Determine which components in your
application originate from other teams and whether those teams plan to develop 64 bit
versions of their code.
� Identify legacy or assembly code. 16-bit Windows-based applications do not run on 64 bit
Editions of Windows and must be rewritten. While x86 assembly code runs in emulation
mode, you may want to rewrite this code to take advantage of the speed of the IA-64
architecture.
� Port the entire application, not just portions of it. Although it is possible to port pieces of
an application or to limit code to 2G with /LARGEADDRESSAWARE:NO, this strategy
trades short-term gain for long-term pain.
� Find substitutes for technologies that will not be ported. Some technologies, including
Data Access Object (DAO) and the Jet Red database engine, will not be ported to 64 bit
Editions of Windows.
� Treat the Windows XP 64 bit Edition as a separate product release. Even though the
Windows 64 bit Edition may share the same code base as your 32 bit, it needs additional
testing and may have other release considerations.
Development
� Start developing compliant code now. Developers can start writing compliant code by
using the latest Platform SDK header files and the new data types with no negative
effects on 32 bit product development. For more information, see Getting Ready for 64 bit
Editions of Windows (http://msdn.microsoft.com/library/psdk/buildapp/64bitwin_410z.htm)
� Ensure that your code can be compiled for both 32- and the Windows XP 64 bit Edition.
The new data model was designed to allow 32- and 64 bit applications to be built from a
9-2 Porting Your Application to the 64 bit Editions of Windows �