Log4j has no support for binary logging format?

Question

I have a need to have Log4j log into a binary format so the logs can be easily machine-interpreted. I know I could use XML for this purpose but don't want the associated file size bloat or parsing overhead.

The whole Layout system seems to be inherently String based, which means I can't use the nice file-rolling appenders. LoggingEvent is serializable, so I'm thinking of writing a binary file appender myself, but I feel like I shouldn't be treading new ground here.

Am I missing something obvious?

Answer 1

I had a very similar problem recently. I had to write the log line to binary format but also wanted to have all the other appenders work normally.

What I did was implement my own appender which extends the AppenderSkeleton and takes the LoggingEvent object where the message returned by getMessage() is my own object.

I also write a class implementing ObjectRenderer which a Layout class of the appender will call in order to transform the logging object (the one I logged) to string.

Then for my own appender (which doesn't have a layout) the message is serialized into binary form and written to some byte stream. For other appenders the layout object calls my object renderer and the message is serialized to String.

In this way all common appenders work the same and I'm still able to append to my own format.

In Summary:

• Write own logging object used this way: logger.info(LogEntry)
• Implement ObjectRenderer to transform LogEntry to String
• Extend AppenderSkeleton with my own BinaryFormatAppender

I don't know of any ready made solution for this.