Class FilterSkeleton

Namespace

log4net.Filter

Assembly

log4net.dll

Subclass this type to implement customized logging event filtering

public abstract class FilterSkeleton : IFilter, IOptionHandler

Inheritance

object

FilterSkeleton

Implements

IFilter

IOptionHandler

Derived

DenyAllFilter

LevelMatchFilter

LevelRangeFilter

LoggerMatchFilter

StringMatchFilter

Inherited Members

object.GetType()

object.MemberwiseClone()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Remarks

Users should extend this class to implement customized logging event filtering. Note that Logger and AppenderSkeleton, the parent class of all standard appenders, have built-in filtering rules. It is suggested that you first use and understand the built-in rules before rushing to write your own custom filters.

This abstract class assumes and also imposes that filters be organized in a linear chain. The Decide(LoggingEvent) method of each filter is called sequentially, in the order of their addition to the chain.

The Decide(LoggingEvent) method must return one of the integer constants Deny, Neutral or Accept.

If the value Deny is returned, then the log event is dropped immediately without consulting with the remaining filters.

If the value Neutral is returned, then the next filter in the chain is consulted. If there are no more filters in the chain, then the log event is logged. Thus, in the presence of no filters, the default behavior is to log all logging events.

If the value Accept is returned, then the log event is logged without consulting the remaining filters.

The philosophy of log4net filters is largely inspired from the Linux ipchains.

Constructors

FilterSkeleton()

protected FilterSkeleton()

Properties

Next

Property to get and set the next filter

public IFilter Next { get; set; }

Property Value

IFilter

The next filter in the chain

Remarks

Filters are typically composed into chains. This property allows the next filter in the chain to be accessed.

Methods

ActivateOptions()

Initialize the filter with the options set

public virtual 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.

Typically filter's options become active immediately on set, however this method must still be called.

Decide(LoggingEvent)

Decide if the LoggingEvent should be logged through an appender.

public abstract FilterDecision Decide(LoggingEvent loggingEvent)

Parameters

loggingEvent LoggingEvent

The LoggingEvent to decide upon

Returns

FilterDecision

The decision of the filter

Remarks

If the decision is Deny, then the event will be dropped. If the decision is Neutral, then the next filter, if any, will be invoked. If the decision is Accept then the event will be logged without consulting with other filters in the chain.

This method is marked abstract and must be implemented in a subclass.