7

The project

The project is a large C# project which is used for test-automation. For this purpose i've to use a java-tool which is the tool which saves all results into a file which can be loaded into a test-environment.

The interface

I got a DLL from the vendor of the test-environment which is build in C++, this dll loads the java environment and loads the jar files.

Current situation

The java environment is loaded with success, its configured with environment-variables set in C# with this method:

String java = GetJavaInstallationPath();
Environment.SetEnvironmentVariable("PATH", String.Format("{0};{1}", Environment.GetEnvironmentVariable("PATH"), Path.Combine(java, @"bin\client")), EnvironmentVariableTarget.Process);

After this i set the path to the java classes using this code:

Environment.SetEnvironmentVariable("ITEPCLASSPATH",
                String.Format("{0};{1}",
                Path.Combine(iTepPath, "itep.jar"),
                Path.Combine(iTepPath, "libs\\itorx.jar")), EnvironmentVariableTarget.Process);

Which actually should work, it shows the correct value when using Environment.GetEnvironmentVariable("ITEPCLASSPATH") but the C++-DLL tells me that it isn't working.

When setting the class path by using a external bat-file it works. Some more facts:

  • The application is started by the bat file
  • The path is copied from my generated path of the dll
  • I don't comment anything out, so the path is still set by C#

It seems that java is not accessing the env.-variable i set in C# but recognizes that i set it in the bat file.

I really need to set the variable via C#, how do i archive this?

Improve this question
9
  • a workaround could be to start the bat file from c# with System.IO.Process.Start. Do you really need to use the DLL? Otherwise, try to find out how the environment gets passed through dlls. I can't see why it doesn't work. I think it should. Commented May 10, 2012 at 12:30
  • @DarenThomas That's a workaround but would make a lot more work for me. :-/ And of course i have to use the DLL and don't have any access to the code of thoose DLL's. Commented May 10, 2012 at 13:06
  • When is the problematic DLL initialized? Maybe it reads the env. variables and remembers the values before you set the value in your code. Commented May 13, 2012 at 16:13
  • @Matej I initialize the DLL by using the Kernel32.dll-method LoadLibrary after i set all the variables. Commented May 13, 2012 at 16:27
  • Do you get the same output for Environment.GetEnvironmentVariables() in your C# app if it is started by the batch file/not by the batch file? Commented May 13, 2012 at 18:10

3 Answers 3

Reset to default
1
+50

It is not explicitly written in Microsoft System.Environment documentation but the target value Process seems to limit scope to the current process only. By default, the CreateProcess method inherits current process environment for the child process. Maybe the parameters used there breaks this default behavior.

So I propose you test first with EnvironmentVariableTarget.User in SetEnvironmentVariable to see if it works better.

By the way, I think you will have to diagnose further environment variable and create process operations with tool like Process Monitor.

Improve this answer
Sign up to request clarification or add additional context in comments.

5 Comments

The process is the same but after setting the env. variable with different targets it works. But this still doesn't answer the question why it's working with a bat-file and not with Environment.SetEnvironmentVariable because a bat is limited to the current process only ( AFAIK ).
The process is not the same - the C# creates a child process to run the JVM, right ? The "bat" file will call the CreateProcess the "right way", I mean with default options so you get expected behavior: environment variables are inherited for the child process. The C# code may use alternate options with the consequence that the created JVM process as other environment variables. So my idea to diagnose with Process Monitor.
No there is only one process, the JVM run's in the same process than the C# process. I checked this.
So probably the JVM has loaded environment variables into a kind of cache before it has been changed by the C# code. In a normal usage, they are not supposed to change during process life. Have you tried Environment.SetEnvironmentVariable without target at all ? Have you track operations on environment variables with Process Monitor ?
The JVM is initialized after the variables are set. No i didn't, maybe i gonna try this out, but i think it targets to Process.
1

Make sure the environment variable works with each target: Process, User and Machine. See this MSDN article. 

// Set the environment variable for the default target (the current process).
Console.WriteLine(fmt2x, "(default)", myVarA, existsA);
Environment.SetEnvironmentVariable(myVarA, existsA);

// Set the environment variable for the the current process.
Console.WriteLine(fmt2x, "Process", myVarB, existsB);
Environment.SetEnvironmentVariable(myVarB, existsB, 
    EnvironmentVariableTarget.Process);

// Set the environment variable for the the current user.
Console.WriteLine(fmt2x, "User", myVarC, existsC);
Environment.SetEnvironmentVariable(myVarC, existsC, 
    EnvironmentVariableTarget.User);

// Set the environment variable for the the local machine.
Console.WriteLine(fmt2x, "Machine", myVarD, existsD);
Environment.SetEnvironmentVariable(myVarD, existsD, 
    EnvironmentVariableTarget.Machine);
Improve this answer

Comments

0

Java allows you to pass environment variables as parameters using the:

java -DMYPROP=MYVALUE myclass.class

argument syntax. Check out the -D flag.

Those system properties then apply to that JVM process instance. Wouldn't that be simpler than trying to modify the OS Environment?

Improve this answer

2 Comments

If the java tool is third-party, you have to use the method(s) the implementors provided, no matter how good or bad they are.
By the way, the option -D set a system property in Java which is accessible with the same API than the environment variables...

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.