Table of Contents

Class EventLogAppender

Namespace
log4net.Appender
Assembly
log4net.dll

Writes events to the system event log.

public class EventLogAppender : AppenderSkeleton, IBulkAppender, IAppender, IOptionHandler, IFlushable
Inheritance
EventLogAppender
Implements
Inherited Members

Remarks

The appender will fail if you try to write using an event source that doesn't exist unless it is running with local administrator privileges. See also http://logging.apache.org/log4net/release/faq.html#trouble-EventLog

The EventID of the event log entry can be set using the EventID property (Properties) on the LoggingEvent.

The Category of the event log entry can be set using the Category property (Properties) on the LoggingEvent.

There is a limit of 32K characters for an event log message

When configuring the EventLogAppender a mapping can be specified to map a logging level to an event log entry type. For example: 

<mapping>
  <level value="ERROR" />
  <eventLogEntryType value="Error" />
</mapping>
<mapping>
  <level value="DEBUG" />
  <eventLogEntryType value="Information" />
</mapping>

The Level is the standard log4net logging level and eventLogEntryType can be any value from the EventLogEntryType enum, i.e.:

  • Erroran error event
  • Warninga warning event
  • Informationan informational event

Constructors

EventLogAppender()

Initializes a new instance of the EventLogAppender class.

public EventLogAppender()

Remarks

Default constructor.

Properties

ApplicationName

Property used to set the Application name. This appears in the event logs when logging.

public string ApplicationName { get; set; }

Property Value

string

The string used to distinguish events from different sources.

Remarks

Sets the event log source property.

Category

Gets or sets the Category to use unless one is explicitly specified via the LoggingEvent's properties.

public short Category { get; set; }

Property Value

short

Remarks

The Category of the event log entry will normally be set using the Category property (Properties) on the LoggingEvent. This property provides the fallback value which defaults to 0.

EventId

Gets or sets the EventId to use unless one is explicitly specified via the LoggingEvent's properties.

public int EventId { get; set; }

Property Value

int

Remarks

The EventID of the event log entry will normally be set using the EventID property (Properties) on the LoggingEvent. This property provides the fallback value which defaults to 0.

LogName

The name of the log where messages will be stored.

public string LogName { get; set; }

Property Value

string

The string name of the log where messages will be stored.

Remarks

This is the name of the log as it appears in the Event Viewer tree. The default value is to log into the Application log, this is where most applications write their events. However if you need a separate log for your application (or applications) then you should set the LogName appropriately.

This should not be used to distinguish your event log messages from those of other applications, the ApplicationName property should be used to distinguish events. This property should be used to group together events into a single log.

MachineName

This property is used to return the name of the computer to use when accessing the event logs. Currently, this is the current computer, denoted by a dot "."

public string MachineName { get; }

Property Value

string

The string name of the machine holding the event log that will be logged into.

Remarks

This property cannot be changed. It is currently set to '.' i.e. the local machine. This may be changed in future.

RequiresLayout

This appender requires a log4net.Layout to be set.

protected override bool RequiresLayout { get; }

Property Value

bool

true

SecurityContext

Gets or sets the SecurityContext used to write to the EventLog.

public SecurityContext? SecurityContext { get; set; }

Property Value

SecurityContext

The SecurityContext used to write to the EventLog.

Remarks

The system security context used to write to the EventLog.

Unless a SecurityContext specified here for this appender the DefaultProvider is queried for the security context to use. The default behavior is to use the security context of the current thread.

Methods

ActivateOptions()

Initialize the appender based on the options set

public override void ActivateOptions()

Remarks

This is part of the IOptionHandler delayed object activation scheme. The ActivateOptions() method must be called on this object after the configuration properties have been set. Until ActivateOptions() is called this object is in an undefined state and must not be used.

If any of the configuration properties are modified then ActivateOptions() must be called again.

AddMapping(Level2EventLogEntryType)

Add a mapping of level to EventLogEntryType - done by the config file

public void AddMapping(EventLogAppender.Level2EventLogEntryType mapping)

Parameters

mapping EventLogAppender.Level2EventLogEntryType

The mapping to add

Remarks

Add a EventLogAppender.Level2EventLogEntryType mapping to this appender. Each mapping defines the event log entry type for a level.

Append(LoggingEvent)

This method is called by the DoAppend(LoggingEvent) method.

protected override void Append(LoggingEvent loggingEvent)

Parameters

loggingEvent LoggingEvent

the event to log

Remarks

Writes the event to the system event log using the ApplicationName.

If the event has an EventID property (see Properties) set then this integer will be used as the event log event id.

There is a limit of 32K characters for an event log message

GetEntryType(Level?)

Get the equivalent EventLogEntryType for a Level level

public virtual EventLogEntryType GetEntryType(Level? level)

Parameters

level Level

the Level to convert to an EventLogEntryType

Returns

EventLogEntryType

The equivalent EventLogEntryType for a Level level

Remarks

Because there are fewer applicable EventLogEntryType values to use in logging levels than there are in the Level this is a one way mapping. There is a loss of information during the conversion.