{-# LANGUAGE CPP #-} {- | Module : System.Log.Handler.Log4jXML Copyright : Copyright (C) 2007-2011 John Goerzen License : BSD3 Maintainer : bjorn.buckwalter@gmail.com Stability : experimental Portability: GHC only? log4j[1] XMLLayout log handlers. Written by Bjorn Buckwalter, bjorn.buckwalter\@gmail.com -} module System.Log.Handler.Log4jXML ( -- * Introduction {- | This module provides handlers for hslogger that are compatible with log4j's XMLLayout. In particular log messages created by the handlers can be published directly to the GUI-based log viewer Chainsaw v2[2]. The set of log levels in hslogger is richer than the basic set of log4j levels. Two sets of handlers are provided with hslogger4j, one which produces logs with hslogger's levels and one which \"demotes\" them to the basic log4j levels. If full hslogger levels are used some Java installation (see below) is necessary to make Chainsaw aware of them. Usage of the handlers in hslogger4j is analoguous to usage of the 'System.Log.Handler.Simple.StreamHandler' and 'System.Log.Handler.Simple.FileHandler' in "System.Log.Handler.Simple". The following handlers are provided: -} -- ** Handlers with hslogger levels log4jStreamHandler, log4jFileHandler, -- ** Handlers with log4j levels log4jStreamHandler', log4jFileHandler' -- * Java install process {- | This is only necessary if you want to use the hslogger levels. Add @hslogger4j.jar@ from @contrib\/java@ to your classpath. To use you will also need to have the jars @log4j-1.3alpha-7.jar@ and @log4j-xml-1.3alpha-7.jar@ that are distributed with Chainsaw on your classpath. (On Mac OS X I added all three jars to @~\/Library\/Java\/Extensions@. It seems that it is not sufficient that Chainsaw already includes its jars in the classpath when launching - perhaps the plugin classloader does not inherit Chainsaw's classpath. Adding the jars to @~\/.chainsaw\/plugins@ wouldn't work either.) If for whatever reason you have to rebuild the hslogger4j jar just run @ant@[3] in the @contrib\/java@ directory. The new jar will be created in the @contrib\/java\/dist@ directory. The Java source code is copyright The Apache Software Foundation and licensed under the Apache Licence version 2.0. -} -- * Chainsaw setup {- | If you are only using the basic log4j levels just use Chainsaw's regular facilities to browse logs or listen for log messages (e.g. @XMLSocketReceiver@). If you want to use the hslogger levels the easiest way to set up Chainsaw is to load the plugins in @hslogger4j-plugins.xml@ in @contrib\/java@ when launching Chainsaw. Two receivers will be defined, one that listens for logmessages and one for reading log files. Edit the properties of those receivers as needed (e.g. @port@, @fileURL@) and restart them. You will also want to modify Chainsaw's formatting preferences to display levels as text instead of icons. -} -- * Example usage {- | In the IO monad: > lh2 <- log4jFileHandler "log.xml" DEBUG > updateGlobalLogger rootLoggerName (addHandler lh2) > h <- connectTo "localhost" (PortNumber 4448) > lh <- log4jStreamHandler h NOTICE > updateGlobalLogger rootLoggerName (addHandler lh) -} -- * References {- | (1) <http://logging.apache.org/log4j/> (2) <http://logging.apache.org/chainsaw/> (3) <http://ant.apache.org/> -} ) where import Control.Concurrent (ThreadId, myThreadId) -- myThreadId is GHC only! import Control.Concurrent.MVar import Data.List (isPrefixOf) import System.IO #if MIN_VERSION_time(1,5,0) import Data.Time.Format (defaultTimeLocale) #else import System.Locale (defaultTimeLocale) #endif import Data.Time import System.Log import System.Log.Handler import System.Log.Handler.Simple (streamHandler, GenericHandler(..)) -- Handler that logs to a handle rendering message priorities according -- to the supplied function. log4jHandler :: (Priority -> String) -> Handle -> Priority -> IO (GenericHandler Handle) log4jHandler showPrio h pri = do hndlr <- streamHandler h pri return $ setFormatter hndlr xmlFormatter where -- A Log Formatter that creates an XML element representing a log4j event/message. xmlFormatter :: a -> (Priority,String) -> String -> IO String xmlFormatter _ (prio,msg) logger = do time <- getCurrentTime thread <- myThreadId return . show $ Elem "log4j:event" [ ("logger" , logger ) , ("timestamp", millis time ) , ("level" , showPrio prio) , ("thread" , show thread ) ] (Just $ Elem "log4j:message" [] (Just $ CDATA msg)) where -- This is an ugly hack to get a unix epoch with milliseconds. -- The use of "take 3" causes the milliseconds to always be -- rounded downwards, which I suppose may be the expected -- behaviour for time. millis t = formatTime defaultTimeLocale "%s" t ++ (take 3 $ formatTime defaultTimeLocale "%q" t) -- | Create a stream log handler that uses hslogger priorities. log4jStreamHandler :: Handle -> Priority -> IO (GenericHandler Handle) log4jStreamHandler = log4jHandler show {- | Create a stream log handler that uses log4j levels (priorities). The priorities of messages are shoehorned into log4j levels as follows: @ DEBUG -> DEBUG INFO, NOTICE -> INFO WARNING -> WARN ERROR, CRITICAL, ALERT -> ERROR EMERGENCY -> FATAL @ This is useful when the log will only be consumed by log4j tools and you don't want to go out of your way transforming the log or configuring the tools. -} log4jStreamHandler' :: Handle -> Priority -> IO (GenericHandler Handle) log4jStreamHandler' = log4jHandler show' where show' :: Priority -> String show' NOTICE = "INFO" show' WARNING = "WARN" show' CRITICAL = "ERROR" show' ALERT = "ERROR" show' EMERGENCY = "FATAL" show' p = show p -- Identical for DEBUG, INFO, ERROR. -- | Create a file log handler that uses hslogger priorities. log4jFileHandler :: FilePath -> Priority -> IO (GenericHandler Handle) log4jFileHandler fp pri = do h <- openFile fp AppendMode sh <- log4jStreamHandler h pri return (sh{closeFunc = hClose}) {- | Create a file log handler that uses log4j levels (see 'log4jStreamHandler'' for mappings). -} log4jFileHandler' :: FilePath -> Priority -> IO (GenericHandler Handle) log4jFileHandler' fp pri = do h <- openFile fp AppendMode sh <- log4jStreamHandler' h pri return (sh{closeFunc = hClose}) -- A type for building and showing XML elements. Could use a fancy XML -- library but am reluctant to introduce dependencies. data XML = Elem String [(String, String)] (Maybe XML) | CDATA String instance Show XML where show (CDATA s) = "<![CDATA[" ++ escapeCDATA s ++ "]]>" where escapeCDATA = replace "]]>" "]]<" -- The best we can do, I guess. show (Elem name attrs child) = "<" ++ name ++ showAttrs attrs ++ showChild child where showAttrs [] = "" showAttrs ((k,v):as) = " " ++ k ++ "=\"" ++ escapeAttr v ++ "\"" ++ showAttrs as where escapeAttr = replace "\"" """ . replace "<" "<" . replace "&" "&" showChild Nothing = "/>" showChild (Just c) = ">" ++ show c ++ "</" ++ name ++ ">" -- Replaces instances of first list by second list in third list. -- Definition blatantly stoled from jethr0's comment at -- http://bluebones.net/2007/01/replace-in-haskell/. Can be swapped -- with definition (or import) from MissingH. replace :: Eq a => [a] -> [a] -> [a] -> [a] replace _ _ [ ] = [] replace from to xs@(a:as) = if isPrefixOf from xs then to ++ drop (length from) xs else a : replace from to as