Logging communication using LogWriter 

Communication logs are very useful when troubleshooting issues at the EWS protocol 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 Ews object):

// create client instance
// ...

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

' create client instance
' ...

' start logging to a file
client.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt")

A sample EWS log file :

2015-11-03 17:12:58.158 Opening log file.
2015-11-03 17:12:58.158 Using FileLogWriter version 2.0.0.0.
2015-11-03 17:12:58.159 INFO Ews(2)[8] HTTP: Connecting to outlook.office365.com:443 using HttpClient 1.0.0.0.
2015-11-03 17:12:58.395 INFO Ews(2)[8] TLS: State StateChange:Negotiating
2015-11-03 17:12:58.481 INFO Ews(2)[8] TLS: State StateChange:Secured
2015-11-03 17:12:58.481 INFO Ews(2)[8] TLS: Connection secured using cipher: TLS 1.1, RSA, 256bit AES in CBC mode, SHA1
2015-11-03 17:12:58.481 INFO Ews(2)[8] HTTP: Sending request: HEAD /EWS/Services.wsdl
2015-11-03 17:12:58.515 INFO Ews(2)[8] HTTP: Received response: 401 Unauthorized.
2015-11-03 17:12:58.515 INFO Ews(2)[8] TLS: Alert Alert:Alert was sent.
2015-11-03 17:12:58.515 INFO Ews(2)[8] TLS: State StateChange:Closed

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