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syslog Log4J Description Comment from syslog  
emerg - Unusable system A “panic” condition usually affecting multiple apps/servers/sites. At this level it would usually notify all tech staff on call.  
alert FATAL Action to be taken immediately Should be corrected immediately, therefore notify staff who can fix the problem. An example would be the loss of a primary ISP connection. Commons-logging: Severe errors that cause premature termination. Expect these to be immediately visible on a status console.  
crit - Critical conditions Should be corrected immediately, but indicates failure in a secondary system, an example is a loss of a backup ISP connection.  
error ERROR Error conditions Non-urgent failures, these should be relayed to developers or admins; each item must be resolved within a given time. Commons-logging: Other runtime errors or unexpected conditions. Expect these to be immediately visible on a status console.  
warning WARN Warning conditions Warning messages, not an error, but indication that an error will occur if action is not taken, e.g. file system 85% full - each item must be resolved within a given time. Commons-logging: Use of deprecated APIs, poor use of API, ‘almost’ errors, other runtime situations that are undesirable or unexpected, but not necessarily “wrong”. Expect these to be immediately visible on a status console.  
notice - Normal but significant condition Events that are unusual but not error conditions - might be summarized in an email to developers or admins to spot potential problems - no immediate action required.  
info INFO Informational message Normal operational messages - may be harvested for reporting, measuring throughput, etc. - no action required. Commons-logging: Interesting runtime events (startup/shutdown). Expect these to be immediately visible on a console, so be conservative and keep to a minimum.  
debug DEBUG Debug-level message Info useful to developers for debugging the application, not useful during operations. Commons-logging: detailed information on the flow through the system. Expect these to be written to logs only.  
  - TRACE Most detailed information Info useful during development to trace execution and values of variables or parameters. Calls with this severity should be removed from the code once the development is finished.

Guidelines

Initialization

Running

Shutdown

Service monitoring

From logs, these information must be retrieved: