Question

OpenExeConfiguration has 2 overloads:

• ConfigurationManager.OpenExeConfiguration (ConfigurationUserLevel) —– (1)
• ConfigurationManager.OpenExeConfiguration (String) —– (2)

OpenMappedExeConfiguration has only 1 prototype:

• OpenMappedExeConfiguration (ExeConfigurationFileMap fileMap,ConfigurationUserLevel userLevel) —– (3)

It seems both (2) and (3) can be used to open a specific config file rather than the default app.config file.

So what’s the difference between them? When to use which?

Why do we seperate the UserLevel and Config File Location in (1) and (2), but combine them in (3)?

Thanks for any replies.

Update

I know that Microsoft always like to do things in more than one ways. But it should do it for a reason. Any body know the reason in my question? Do we need a bounty 😉 ?

Answer 1

The difference is explained in the ultimate .NET config resource – Cracking the Mysteries of .NET 2.0 Configuration:

OpenExeConfiguration (String)

will append “.config” to the filename
you provide and load that
configuration file. It’s important to
note that OpenExeConfiguration(string
exePath) is a very misleading method,
as the filename does not have to be
the filename of the .exe that is
running […]
By providing a filename other than the
EXE filename, an alternate *.config
file can be opened.

OpenExeConfiguration (ConfigurationUserLevel)

The second method,
OpenExeConfiguration(ConfigurationUserLevel
level) will load the appropriate
configuration file for the specified
configuration level. Configuration
levels, available in the Exe context,
allow you to specify whether you want
exe, roaming user, or local user
configuration […] Remember that configuration is hierarchical and merged. When requesting roaming or local user configuration, that level up through machine.config are merged, resulting in the complete configuration accessible by your application for the given user level.

OpenMappedExeConfiguration(), OpenMappedMachineConfiguration()

Unlike the OpenExeConfiguration()
methods, which make several
assumptions about where your
configuration files reside,
OpenMappedExeConfiguration() and
OpenMappedMachineConfiguration() allow
you to explicitly specify where your
*.config files reside on disk. Using these methods, you can load an
alternate machine.config, load
User.config files from the locations
of your own choosing (vs. letting the
.NET framework decide on some
convoluted path), etc. When accessing
machine.config, a custom version is
not required,
OpenMachineConfiguration() should be
used instead.