How does a native calling application get a return value from JNLP?

Question

I am launching a JNLP java application from a native client app (i.e. not a browser). When the JNLP finishes it's task, I need it to return a string to the calling app? How can I do this? Is it possible to return a value to a calling app - or do I need to have the calling app listen on a port and have the JNLP app write the value to that port through sockets?

Cryogen

Please, can you post an example of how are you doing the call? – Christianechristiania

@karelss - javaws <jnlp file> is called by Process::Start in C# – Cryogen

Answer 1

Answering my own question!

I write to stdout from the child process (the JNLP)

• The parent launches the child process

  Process::Start
  

• Read stdout from Parent

  string ret = process.StandardOutput.ReadToEnd();
  

• Process::WaitForExit();
  

Anyone sees any problem in this?

Cryogen

Answer 2

If the all-permissions element is specified, you could try to set an environment variable which you can read from your C# application.

Set environment variable in Java:

System.getenv().put("returnValue", "yourValue");

Read environment variable in C#:

ProcessStartInfo p = new ProcessStartInfo("start ....");
....
string returnValue = p.EnvironmentVariables["returnValue"];

Biliary

Don't think this will work - child is a separate process - it inherits a copy of the env variables of the parent - any changes in the variable values in the child will not be reflected in the parent - at least this is how it works on most operating systems - will test it on windows and see. – Cryogen

Answer 3

I like your idea to use sockets and think this is could be an easy solution.

It is not possible to get return values from a WebStart-application. Just see the help message from

javaws --help

There is no return-code available. (Sorry)

Have you thougth on a temporary file instead of the sockets?

Spur

Answer 4

It's a bit old but as fas as i know this is the exiting options to intercommunicate two process link.

I think the easiest way to solve your problem is use rmi, or jmx if you can, or just a simple socket

Christianechristiania