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IEventSource Interface

Note: This interface is new in the .NET Framework version 2.0.

Defines the events raised by the build engine. Loggers receive an object implementing this interface in their Initialize method and use it to subscribe to the events they are interested in receiving.

Namespace: Microsoft.Build.Framework
Assembly: Microsoft.Build.Framework (in microsoft.build.framework.dll)

public interface IEventSource
public interface IEventSource
public interface IEventSource

The following example shows how to write a basic logger that responds to build events.

using System;
using System.IO;
using System.Security;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace MyLoggers
{
	// This logger will derive from the Microsoft.Build.Utilities.Logger class,
	// which provides it with getters and setters for Verbosity and Parameters,
	// and a default empty Shutdown() implementation.
	public class BasicFileLogger : Logger
	{
		/// <summary>
		/// Initialize is guaranteed to be called by MSBuild at the start of the build
		/// before any events are raised.
		/// </summary>
		public override void Initialize(IEventSource eventSource)
		{
			// The name of the log file should be passed as the first item in the
			// "parameters" specification in the /logger switch.  It is required
			// to pass a log file to this logger. Other loggers may have zero or more than 
			// one parameters.
			if (null == Parameters)
			{
				throw new LoggerException("Log file was not set.");
			}
			string[] parameters = Parameters.Split(';');
			
			string logFile = parameters[0];
			if (String.IsNullOrEmpty(logFile))
			{
				throw new LoggerException("Log file was not set.");
			}
			
			if (parameters.Length > 1)
			{
				throw new LoggerException("Too many parameters passed.");
			}
			
			try
			{
				// Open the file
				this.streamWriter = new StreamWriter(logFile);
			}
			catch (Exception ex)
			{
				if
				(
					ex is UnauthorizedAccessException
					|| ex is ArgumentNullException
					|| ex is PathTooLongException
					|| ex is DirectoryNotFoundException
					|| ex is NotSupportedException
					|| ex is ArgumentException
					|| ex is SecurityException
					|| ex is IOException
				)
				{
					throw new LoggerException("Failed to create log file: " + ex.Message);
				}
				else
				{
					// Unexpected failure
					throw;
				}
			}

			// For brevity, we'll only register for certain event types. Loggers can also
			// register to handle TargetStarted/Finished and other events.
			eventSource.ProjectStarted += new ProjectStartedEventHandler(eventSource_ProjectStarted);
			eventSource.TaskStarted += new TaskStartedEventHandler(eventSource_TaskStarted);
			eventSource.MessageRaised += new BuildMessageEventHandler(eventSource_MessageRaised);
			eventSource.WarningRaised += new BuildWarningEventHandler(eventSource_WarningRaised);
			eventSource.ErrorRaised += new BuildErrorEventHandler(eventSource_ErrorRaised);
			eventSource.ProjectFinished += new ProjectFinishedEventHandler(eventSource_ProjectFinished);
		}

		void eventSource_ErrorRaised(object sender, BuildErrorEventArgs e)
		{
			// BuildErrorEventArgs adds LineNumber, ColumnNumber, File, amongst other parameters
			string line = String.Format(": ERROR {0}({1},{2}): ", e.File, e.LineNumber, e.ColumnNumber);
			WriteLineWithSenderAndMessage(line, e);
		}
		
		void eventSource_WarningRaised(object sender, BuildWarningEventArgs e)
		{
			// BuildWarningEventArgs adds LineNumber, ColumnNumber, File, amongst other parameters
			string line = String.Format(": Warning {0}({1},{2}): ", e.File, e.LineNumber, e.ColumnNumber);
			WriteLineWithSenderAndMessage(line, e);
		}

		void eventSource_MessageRaised(object sender, BuildMessageEventArgs e)
		{
			// BuildMessageEventArgs adds Importance to BuildEventArgs
			// Let's take account of the verbosity setting we've been passed in deciding whether to log the message
			if ((e.Importance == MessageImportance.High && IsVerbosityAtLeast(LoggerVerbosity.Minimal))
				|| (e.Importance == MessageImportance.Normal && IsVerbosityAtLeast(LoggerVerbosity.Normal))
				|| (e.Importance == MessageImportance.Low && IsVerbosityAtLeast(LoggerVerbosity.Detailed))				
				)
			{
				WriteLineWithSenderAndMessage(String.Empty, e);
			}
		}

		void eventSource_TaskStarted(object sender, TaskStartedEventArgs e)
		{
			// TaskStartedEventArgs adds ProjectFile, TaskFile, TaskName
			// To keep this log clean, this logger will ignore these events.
		}
		
		void eventSource_ProjectStarted(object sender, ProjectStartedEventArgs e)
		{
			// ProjectStartedEventArgs adds ProjectFile, TargetNames
			// Just the regular message string is good enough here, so just display that.
			WriteLine(String.Empty, e);
			indent++;
		}

		void eventSource_ProjectFinished(object sender, ProjectFinishedEventArgs e)
		{
			// The regular message string is good enough here too.
			indent--;
			WriteLine(String.Empty, e);
		}
		
		/// <summary>
		/// Write a line to the log, adding the SenderName and Message
		/// (these parameters are on all MSBuild event argument objects)
		/// </summary>
		private void WriteLineWithSenderAndMessage(string line, BuildEventArgs e)
		{
			if (0 == String.Compare(e.SenderName, "MSBuild", true /*ignore case*/))
			{
				// Well, if the sender name is MSBuild, let's leave it out for prettiness
				WriteLine(line, e);
			}
			else
			{
				WriteLine(e.SenderName + ": " + line, e);
			}
		}
		
		/// <summary>
		/// Just write a line to the log
		/// </summary>
		private void WriteLine(string line, BuildEventArgs e)
		{
			for (int i = indent; i > 0; i--)
			{
				streamWriter.Write("\t");
			}
			streamWriter.WriteLine(line + e.Message);
		}
		
		/// <summary>
		/// Shutdown() is guaranteed to be called by MSBuild at the end of the build, after all 
		/// events have been raised.
		/// </summary>
		public override void Shutdown()
		{
			// Done logging, let go of the file
			streamWriter.Close();
		}

		private StreamWriter streamWriter;
		private int indent;
	}
}

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

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