Logging communication using LogWriter 

Communication logs are very useful when troubleshooting issues at the Graph API on communication level. Whenever you run into a problem, a log makes it possible to see what is going on.

To start logging, just add the following line into your code (just after creating the GraphClient object):

// create client instance
// ...

// start logging to a file
client.LogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt");

A sample log file:

2024-05-15 09:41:08.015 Opening log file.
2024-05-15 09:41:08.949 INFO GraphClient(1)[5] Graph: Executing Connect method.
2024-05-15 09:41:08.949 INFO GraphClient(1)[5] Graph: Connecting to https://graph.microsoft.com:443 using GraphClient.
2024-05-15 09:41:09.013 INFO GraphClient(1)[5] Graph: Executing Login method.
2024-05-15 09:41:09.014 INFO GraphClient(1)[5] Graph: Authenticating to server using OAuth 2.0.
2024-05-15 09:41:09.077 INFO GraphClient(1)[5] Graph: Authenticated as user@example.com.
2024-05-15 09:41:09.087 INFO GraphClient(1)[5] Graph: Executing StoreMessage method.
2024-05-15 09:41:09.384 INFO GraphClient(1)[5] Graph: Executing MoveMessage method.

Log verbosity levels 

There are several levels of log verbosity:

• Error - logs error messages only
• Info - default level; logs important informative messages as well
• Debug - logs all messages useful for debugging purposes
• Verbose - very detailed log for advanced analysis; logs content of communication packets
  Warning: At the Verbose level, user credentials are written to the log as well.

To specify a log level, just pass an argument to FileLogWriter's constructor:

// create client instance
// ...

// start logging to a file at debug level
client.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to a file at debug level
client.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

Built-in log writers 

Text file

To log into a text file, use FileLogWriter:

// create client instance
// ...

// start logging to a file at debug level
client.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to a file at debug level
client.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

.NET trace listener

To log to .NET Trace Listeners, use TraceLogWriter:

// create client instance
// ...

// start logging to subscribed trace listeners
client.LogWriter = new Rebex.TraceLogWriter(Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to subscribed trace listeners
client.LogWriter = New Rebex.TraceLogWriter(Rebex.LogLevel.Debug)

Standard output stream

To log to the standard output stream, use ConsoleLogWriter:

// create client instance
// ...

// start logging to the standard output stream at debug level
client.LogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to the standard output stream at debug level
client.LogWriter = New Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug)

Logging to multiple log writers

To log to more log writers at the same time, use TeeLogWriter:

var consoleLogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);
var fileLogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt", Rebex.LogLevel.Info);

// start logging to both console and file log writers
client.LogWriter = new Rebex.TeeLogWriter(consoleLogWriter, fileLogWriter);

Dim consoleLogWriter = New Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug)
Dim fileLogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

' start logging to both console and file log writers
client.LogWriter = New Rebex.TeeLogWriter(consoleLogWriter, fileLogWriter)

Writing custom log writers 

// Sample log writer that logs to the standard error output stream
public class MyLogWriter : LogWriterBase
{
    protected override void WriteMessage(string message)
    {
        Console.Error.WriteLine("Rebex: {0}", message);
    }
}

' Sample log writer that logs to the standard error output stream
Public Class MyLogWriter
    Inherits LogWriterBase
    Protected Overrides Sub WriteMessage(message As String)
        Console.Error.WriteLine("Rebex: {0}", message)
    End Sub
End Class