Question

I am using install4j to install an intranet application which requires an HTTP and HTTPS port. I would like to test that these ports are available and warn the user/block the installation until they select unavailable ports.

The only avenue I see for this (besides custom code) is to ensure the windows service fails if the application cannot bind to needed ports, and use a Failure Strategy “Ask user whether to retry or quit on failure”. In the web server startup code, I use System.exit(1) if the server cannot bind to ports. However, this does not appear to register as a failure to the installer – the installation proceeds without invoking the failure strategy.

What is the proper approach for signaling failure to the “Start a service” action? Have other people taken an alternate approach to guaranteeing the installation uses available ports?

Answer 1

A good alternate approach I’ve since found: add a custom code action:

List<Integer> takenPorts = new ArrayList<Integer>();
for (int port : Arrays.asList(80, 443)) {
    java.net.ServerSocket socket = null;
    try {
        socket = new java.net.ServerSocket(port);
    } catch (IOException e) {
        takenPorts.add(port);
    } finally { 
        if (socket != null) socket.close(); 
    }
}

if (takenPorts.isEmpty()) {
     return true;
}
else {
    String msg;
    if (takenPorts.size() == 2) {
        msg = "Ports 80 and 443 must be available for uDiscovery";
    }
    else {
        msg = "Port " + takenPorts.get(0) + " must be available for uDiscovery";
    }
    context.setVariable("portErrorMessage", msg);
    return false;
}

Good explanation of how to wire this up here