Question

Hello friends i need an explanation regarding .NET framework pre-requisite while installing the published application in the target machine.

As java is downward compatible, by which i mean that if i have installed java v1.6 and if the application is developed using java v1.5 (i also mean that only classes and packages available in 1.5 are used to build the appln.)

I am sure that the application developed will definitely run by installing the latest or higher versions of jre or j2se.

Similarly in the case of .NET platform suppose if i develop my application using .NET framework 3.5 and in the target machine i have installed .NET framework 4.0 (the latest) even then it prompts to install the .NET framework 3.5 why is this so?

The real time example is i have downloaded and tried installing MySQL workbench and also installed .NET framework 4.0 But it still asks to install the .NET framework 3.5 before running the MySQL installation.

My question is does .NET framework is downward compatible as java or .NET?

Answer 1

Version Compatibility in the .NET Framework:

The .NET Framework 4 is
backward-compatible with applications
that were built with the .NET
Framework versions 1.1, 2.0, 3.0, and
3.5. In other words, applications and components built with previous
versions of the .NET Framework will
work on the .NET Framework 4.

However, in practice, this
compatibility can be broken by
seemingly inconsequential changes in
the .NET Framework and changes in
programming techniques. For example,
performance improvements in the .NET
Framework 4 can expose a race
condition that did not occur on
earlier versions. Similarly, using a
hard-coded path to .NET Framework
assemblies, performing an equality
comparison with a particular version
of the .NET Framework, and getting the
value of a private field by using
reflection are not backward-compatible
practices. In addition, each version
of the .NET Framework includes bug
fixes and security-related changes
that can affect the compatibility of
some applications and components.

If your application or component does
not work as expected on the .NET
Framework 4, use the following
checklists.

For .NET Framework 2.0, 3.0, and 3.5 applications:

Check .NET Framework 4 Migration
Issues for any changes that might
affect your application and apply the
workaround described.

If you are recompiling existing source
code to run on the .NET Framework 4,
or if you are developing a new version
of an application or component that
targets .NET Framework 4 from an
existing source code base, check
What’s Obsolete in the .NET Framework
for obsolete types and members, and
apply the workaround described.
(Previously compiled code will
continue to run against types and
members that have been marked as
obsolete.)

If you determine that a change in the
.NET Framework 4 has broken your
application, check the Runtime
Settings Schema to determine whether
you can use a runtime setting in your
application configuration file to
restore the previous behavior.

If you encounter an issue that is not
documented, file a Microsoft Connect
bug and contact [e-mail]
with the bug number.