Post a Comment On: the urban canuk, eh

I recently wrote a simple windows service that hosted batch files and other applications within a service process. I found some great stuff located here, which really helped me along. Like many other developers, I quickly discovered that debugging and diagnosing issues wasn't particularily easy. On my machine, it was fairly simple to set a break point and manually attach to the service, but diagnosing issues on other machines lacked detail in the Event Log. What I needed was a way to capture the output of my hosted application. As I was already using log4net to trace through application flow, I used the following approach to redirect the output of my hosted application into my logger.
using System.Diagnostics;
using log4net;

public class MyService : ServiceBase
{
private static readonly ILog log = LogManager.GetLogger(typeof(MyService));

private Process process;

public override void OnStart(string[] args)
{
process = new Process();

ProcessStartInfo info = new ProcessStartInfo();

// configure the command-line app.
info.FileName = "java.exe"
info.WorkingDirectory = "c:\program files\Selenium\RemoteControlServer"
info.Arguments = "-jar selenium-server.jar"

// configure runtime specifics
info.UseShellExecute = false; // needed to redirect output
info.RedirectStandardOutput = true;
info.RedirectErrorOutput = true;

process.StartInfo = info;

// setup event handlers
process.EnableRaisingEvents = true;
process.ErrorDataReceived += new DataReceivedEventHandler(process_ErrorDataReceived);
process.OutputDataReceived += new DataReceivedEventHandler(process_OutputDataReceived);


process.Start();

// notify process about asynchronous reads
process.BeginErrorReadLine();
process.BeginOutputReadLine();

}

// fires whenever errors output is produced
private static void process_ErrorDataReceived(object sender, DataReceivedEventArgs e)
{
try
{
if (!String.IsNullOrEmpty(e.Data))
{
log.Warn(e.Data);
}
}
catch(Exception ex)
{
log.Error("Error occurred while trying to log console errors.", ex)
}
}

// fires whenever standard output is produced
private static void process_OutputDataReceived(object sender, DataReceivedEventArgs e)
{
try
{
if (!String.IsNullOrEmpty(e.Data)
{
log.Debug(e.Data);
}
}
catch(Exception ex)
{
log.Error("Error occurred while trying to log console output.", ex);
}
}
}