Nuix Java API Project - Switching Engine Releases at runtime about nuix-java-engine-baseline HOT 3 CLOSED

Hello @chrishaupt, I believe the way Nuix Workstation (the GUI) gets around not having to have the OS Path environment variable include every installed version of Nuix is by setting the Path environment variable for the JVM process started up by nuix_app.exe.

For example, if you start Nuix Workstation and then run the following Ruby script in the script console:

# Get environment variable "Path"
puts java.lang.System.getenv("Path").gsub(";","\n")

You should see output similar to the following:

C:\Program Files\Nuix\Nuix 9.2\bin
C:\Program Files\Nuix\Nuix 9.2\bin\amd64
C:\Program Files\Nuix\Nuix 9.2\bin\x86
C:\Program Files\Nuix\Nuix 9.2\jre\bin
C:\Program Files\Nuix\Nuix 9.2\jre\bin\server
C:\Python39\Scripts\
C:\Python39\
C:\WINDOWS\system32
C:\WINDOWS
etc...

If I then open a command prompt and echo the same variable using:

ECHO %path%

I instead get a listing without the Nuix path entries:

C:\Python39\Scripts\
C:\Python39\
C:\WINDOWS\system32
C:\WINDOWS
etc...

You see that while from the perspective of the running Nuix Java process those path values are present, the OS doesn't have them. So I believe nuix_app.exe is doing the following:

1. Start JVM process which runs the Nuix main method
2. Inject into the Path environment variable of that JVM process the relevant additional path entries

The way I might approach this is by writing a similar executable that starts up my JVM/Nuix engine process. I rather like C#/.NET so below here is a snippet that demonstrates the general concept in C#/.NET using the Process class:

// The paths you have decided to add through whatever means, such as
// a little GUI that user selects version they want to run against
string[] additionalPaths = new string[] {
    "D:\engine-releases\9.0.1.325\bin",
    "D:\engine-releases\9.0.1.325\bin\x86",
};

Process engineProcess = new Process();

// The executable to execute
engineProcess.StartInfo.FileName = "C:\Path\To\java.exe";

// The arguments provided to executable above, things like class path, fully qualified name of class
// with static main method, maybe even Nuix specific arguments, etc
engineProcess.StartInfo.Arguments = "-classpath \"D:\\engine-releases\\9.0.1.325\\lib\\*;.\\*\" com.nuix.javaenginesimple.examples.BasicInitializationExample"

// Any additional process configuration you may want to set
engineProcess.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
engineProcess.StartInfo.CreateNoWindow = true;

// Perhaps additional configuration such as standard out and standard error redirection, etc...

// Modify the "Path" environment variable of only the JVM process we are about to start
for (string additionalPath in  additionalPaths) {
    engineProcess.EnvironmentVariables["Path"] += ";"+additionalPath;
}

// Start the process
engineProcess.Start();

from nuix-java-engine-baseline.

Thank you for this in depth answer! I thought about starting my applikation via batch script (SET Path/to/Bin). But your idea is much more convenient.

from nuix-java-engine-baseline.

Hello @chrishaupt, I wanted to add that the batch file approach can work in a similar manner by using SETLOCAL and ENDLOCAL commands, which allows you to localize the modifications to environment variables to just between those 2 commands. I've used both approaches (C#/.NET and batch file) to temporarily set environment variables NUIX_USERNAME and NUIX_PASSWORD to temporarily provide NMS credentials when running a script headless via nuix_console.exe.

from nuix-java-engine-baseline.