Managing the Windows Event Log

WindowsEventLog is part of the CategoryAplTree project.

Overview

This class offers methods useful to read from and write to the Windows Event Log.

The Windows Event Log is important to many large organisation due to the fact that servers situated in a special room cannot be accessed easily, not even by an administrator, and that monitoring them has to be done remotely as a conseqence. The Windows Event Log can be easily monitored remotely and is therefore the ideal place to report "Start", "Stop", "Fatal Error", Security problems and more.

Windows Event Log Classes

There are a number of so-called classes available in the Windows Event Log:

There might be others as well. It is possible to create your own class, although this is not recommended.

An APL application programmer is likely to want to write into the "Application" class. Therefore, the WindowsEventLog class defaults to that Window Event Log class.

Source

Note that within a class you must specify a source, normally your application name. Note further that the name of the source must be unqiue across all classes, not only the class you try to write to!

Example: there is a source "Server" in the "Application" class on my machine. Although I can create a new class "MyAppl", I cannot use "Server" as a source name as a consequence!

.NET

The WindowsEventLog class uses .NET but tries to hide everything not needed for an APL application programmer, or to use appropriate defaults.

Security

Using this class without Admin rights, for example when your application runs as a service, needs "EventLogPermission" rigths. On a server you cannot control this might be a problem. Microsoft explicitly points out that granting this right is a security risc and should therefore only be given to code that is fully managed (trusted).

In order to write to a source "myApp" in the "Application" class:

• Start regedit
• Locate the following registry subkey:

HKLM\SYSTEM\CurrentControlSet\Services\Eventlog\Application

• Right-click the Application subkey, point to "New," and then click Key.
• Type myApp for the key name.
• Close Registry Editor.

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Example

 my←⎕NEW #.WindowsEventLog(,⊂'MyApp')
 my.WriteInfo 'Server started'
 my.WriteWarning 'Low on memory'
 my.WriteError 'Fatal error, server stopped'
 my.WriteInfo 'Server started'

Problems

When you get this:

System.Security.SecurityException: The source was not found, but some or all event logs could not be searched.  Inaccessible logs: Security.
        (   at System.Diagnostics.EventLog.FindSourceRegistration(String source, String machineName, Boolean readOnly)
   at System.Diagnostics.EventLog.SourceExists(String source, String machineName)
   at System.Diagnostics.EventLog.SourceExists(String source))

this is because Microsoft in its wisdom has refused to grant "Read" permission to parts of the Event log in some versions of the Windows operating system. I wasn't able to establish a pattern...

Follow these steps in order to solve the problem:

1. Select Start - Run, then enter: regedt32

2. Navigate/expand to the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\Security

3. Right click on this entry and select Permissions
4. Add the user name
5. Give it Read permission

Project Page

For bug reports, future enhancements and a full version history see WindowsEventLog/ProjectPage

Version Information

CategoryAplTree