Rolling Flat File event sink

The RollingFlatFileSink class is defined in the Microsoft.Practices.EnterpriseLibrary.SemanticLogging.Sinks namespace. It is included in the Semantic Logging Application Block – Text file sinks package obtainable from NuGet.

The name of the extension method used to create a sink and subscribe it to an event listener is LogToRollingFlatFile.

The method CreateListener in the RollingFlatFileLog class creates an observable listener and a RollingFlatFileSink instance, and subscribes the sink to the listener.

The following table describes the parameters of the LogToRollingFlatFile and CreateListener methods. If you are using the application block out-of-process, you set these parameters using the configuration file for the Out-of-Process Host. See Configuration schema for the out-of-process model for details.

Notes

• If you set the maxArchivedFiles parameter, the event sink will delete (purge) files using the file name pattern **[file-name] *.**file-extension. Therefore, it will delete all log files for any event sink that matches this pattern when it purges archived log files. To prevent this, use a value for the File Name parameter that includes an additional period. For example, use **[file-name].[additional-name].**file-extension.
• You can control the size of the file, its age, or both. For example, if you specify in configuration a rollSizeKB value of 5 and a rollInterval value of Day, the file rolls when its size exceeds 5 KB and it also rolls at the end of the day.
• If you select Increment for the rollFileExistsBehavior parameter, the application block creates a new file when the existing file rolls over. The file name includes the current timestamp. If a file with this name already exists, the application block adds an integer to the end of the timestamp and increments it until it cannot find a file with that name. For example, assume there is a file named mylog2007-01-10.log and the file rolls over while that timestamp is still valid. The sink will then look for a file named mylog2007-01-10.1.log. If no such file exists, it will use that file name for the new file. If that file also exists, it will then attempt to locate the log with the next sequence number mylog2007-01-10.2.log.
• If you select Overwrite for the rollFileExistsBehavior parameter, the sink replaces the existing file with a new file when the current file rolls over. However, if you also set the timeStampPattern parameter, the sink will create a new file with the current time stamp instead of replacing the existing file. If for some reason it cannot overwrite the file, it will generate a name using the same process that is used with the Increment value. The choice of value for the timeStampPattern property affects whether a new file is created. For example, if the rollInterval is set to minute and the timeStampPattern is set to "hh-mm,” a new file is created every minute with the hour and minute appended to the file name. However, if the rollInterval is set to minute and the timeStampPattern is set to "yyyy,” then the log file with the year appended to its name is overwritten every minute. For more information about time stamp patterns, see Custom Date and Time Format Strings on MSDN.
• Relative path names resolve to a location that is relative to the AppDomain.CurrentDomain.BaseDirectory directory.

The following table shows the information that is output by the Rolling Flat File event sink. The formatter used by the Rolling Flat File event sink determines the actual content of the messages. For more information, see Choosing and using text formatters.

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