I've gotten pretty familiar with the file, smtp, adonet, and eventlog
appenders, and have even written my own simple extensions. Now I'm being
asked to make log4net logging happen over the public internet from a .NET
Winforms client app, and I'm on unfamiliar ground.

The client is a .NET Winforms app that will do some work locally and hit up
servers over http via .NET web services for other work, but log entries must
be made to the central servers. My customer doesn't want to log locally and
then have users email local logs; they want to see errors and info entries
as they happen, or pretty soon thereafter. Ultimately, log entries are to be
written to NTFS files a la FileAppender.

I'm talking about something resembling a "Web Services Appender", methinks.

Is there some relatively easy way to achieve this with RemotingAppender and
an almost-empty server host in IIS that just passes everything through via a
server-side log4net config file that names a FileAppender? Or is there
another, better approach?

I'm looking for general advice, samples, links to other resources - anything
at all. Grateful for whatever tidbits I can get that don't take up too much
of folks' time. Thanks in advance.

-BillyB

It looks like NLog has a stub WebService target:

http://svn.sav.net/repos/nlog/trunk/NLog/src/NLog/Targets/WebService.cs

A naive approach may be to render the message with XmlLayoutSchemaLog4j
then POST it to a page on the server.

No, but its pretty easy to write one.  We had exactly the same situation
where we need to post errors to the server and use a webservice to do it.
Here's a pretty simple one, but it was written for a previous version of
Log4Net but should give general idea (btw, InitializeService is a method
that was created to set security, urls, etc. on the webservice).

/// <summary>
/// Summary description for ServiceAppender.
/// </summary>
public class ServiceAppender : AppenderSkeleton
{
 public ServiceAppender()
 {
  //Do any intialization here.
 }

 #region Implementation of IOptionHandler

 public override void ActivateOptions()
 {
  base.ActivateOptions ();

  //Provide any checks based on Service config properties, if Service
  //config properties are valid initialize ServiceAppender.

  InitializeServiceConnection();
 }


 #endregion

 #region Override implementation of AppenderSkeleton

 protected override void Append(LoggingEvent loggingEvent)
 {
  //Set any necessary loggingEvent properties.
  //(e.g. loggingEvent.Properties[LoggingEvent.HostNameProperty] =
SystemInfo.HostName;
  /* TODO */

  try
  {
   //Call the WebService Logger.
   // TODO: Decide how to proceed. This normally is controlled from the
App.Config file,
   //   but if it gets changed to something less than a level of Error by
someone
   //   not knowing the ramifications, it could cause an enormous amount of
traffic.

   // TODO: I want to checkin a workable copy, I don't have rights to update
manaslu with updated WebService.  After updating manaslu then uncomment and
checkin.
   //if (loggingEvent.Level.Name.ToUpper() == "ERROR" ||
loggingEvent.Level.Name.ToUpper() == "FATAL")
    _serviceLogging.RMSServiceLogger(loggingEvent.Level.Name,
loggingEvent.RenderedMessage, Environment.UserName,
Environment.UserDomainName,
((AppBaseLoader)AppLoader.Instance).PersonSystemUserGuid,
SystemInfo.HostName);
  }
  catch(Exception exc)
  {
   ErrorHandler.Error("Unable to send loggingEvent to Logging Service", exc,
ErrorCodes.WriteFailure);
  }
 }


 protected override bool RequiresLayout
 {
  get { return false; }
 }


 public override void OnClose()
 {
  base.OnClose ();

  //Release any resource that were needed.

 }

 #endregion

 #region Private Methods

 private void InitializeServiceConnection()
 {
  try
  {
   //Code any Service initialization needed for ServiceAppender to work.
   //This is called from ActiveOptions.
   //Instantiate the WebService.
   if (_serviceLogging == null)
    _serviceLogging =
(Logging.LoggingService)InitializeService(typeof(Logging.LoggingService));
  }
  catch(Exception exc)
  {
   // TODO: Add Service name to error message.
   ErrorHandler.Error("Could not initialize the service", exc,
ErrorCodes.GenericFailure);

   // TODO: Reset the Service object to a known state if needed.
  }
 }

 #endregion

 #region Fields

 private Logging.LoggingService _serviceLogging = null;

 #endregion

Yes, we only use it on error and fatal messages, so usually its not that
time consuming.  Also its set to use an async call so it doesn't wait for a
return message.  That all being said, Georg is right about the relative
slowness of the web services.

I looked at this a while back and wrote my own web services appender. I first wrote it to send a fixed set of log parameters, but then you have a problem if you ever write exensions to log4net and your set of parameters changes. You would also have to change your web service methods each time. Then I tried to send over the log4net event object itself, but ran into serialization issues. Maybe others got this to work, but I ended up scrapping this approach.

I found .NET Remoting to be so much easier to deal with. If you have a .NET client and .NET server then you can use binary Remoting over TCP (as opposed to SOAP), which offers better performance and you don't need to worry about serialization. To make it even easier, if you look at the sample code in the log4net distribution, you will find a .NET Remoting server and a full example. This server also uses log4net, so on the receiving end you use log4net to log the events, meaning you can log them to files, databases, or whatever you want.

I have been using this approach for almost a year now. I have a bunch of application servers that use .NET Remoting appenders to log to a centralized cluster of "logging servers". These logging servers run the .NET Remoting Server (I run it as an NT service), listen on a port for incoming events, and when events are received it uses log4net to route the events to final destination (usually a database).

I actually wrote my own .NET Remoting appender that would make the calls asynchronous, but this was with 1.2.8, and I believe 1.2.9 has asynchronous built in with the .NET Remoting appender. I think the only case where you would want to use a web service appender instead of Remoting is either when your environment is not all .NET-based, or you can only open port 80 on your firewall (.NET remoting requires a port other than 80 to be open).

Simon.

-----Original message-----
From: "Billy Barnum" bbarnum@spamcop.net
Date: Sun, 15 Jan 2006 23:30:18 -0800
To: log4net-user@logging.apache.org
Subject: Is there anything resembling a "WebServicesAppender"?

> I've gotten pretty familiar with the file, smtp, adonet, and eventlog
> appenders, and have even written my own simple extensions. Now I'm being
> asked to make log4net logging happen over the public internet from a .NET
> Winforms client app, and I'm on unfamiliar ground.
>
> The client is a .NET Winforms app that will do some work locally and hit up
> servers over http via .NET web services for other work, but log entries must
> be made to the central servers. My customer doesn't want to log locally and
> then have users email local logs; they want to see errors and info entries
> as they happen, or pretty soon thereafter. Ultimately, log entries are to be
> written to NTFS files a la FileAppender.
>
> I'm talking about something resembling a "Web Services Appender", methinks.
>
> Is there some relatively easy way to achieve this with RemotingAppender and
> an almost-empty server host in IIS that just passes everything through via a
> server-side log4net config file that names a FileAppender? Or is there
> another, better approach?
>
> I'm looking for general advice, samples, links to other resources - anything
> at all. Grateful for whatever tidbits I can get that don't take up too much
> of folks' time. Thanks in advance.
>
> -BillyB
>