25. Processing Logs
This chapter deals with various tasks that might be required after a log message is received by NXLog.
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Parsing Various Formats – Reading fields from several common log formats 
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Alerting – Generating alerts when specific conditions are met 
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Using Buffers – Using disk- and memory-based buffering in NXLog 
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Character Set Conversion – Converting between character sets during processing 
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Detecting a Dead Agent or Log Source – Generating alerts when a remote agent or log source stops sending logs 
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Event Correlation – Using a dedicated module for detecting conditions based on a sliding window 
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Extracting Data – Implementing parsing using module procedures or regular expressions 
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Filtering Messages – Discarding events based on specified conditions 
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Format Conversion – Configuring conversion between input and output formats 
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Log Rotation and Retention – Setting up policies for automatically retaining and discarding past log data 
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Message Classification – Matching and tagging events 
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Parsing Multi-Line Messages – Joining and parsing messages that span multiple lines 
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Rate Limiting – Reducing the speed at which messages are read from a log source 
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Rewriting and Modifying Messages – Making changes to log messages during processing 
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Timestamps – Working with timestamp strings and datetime values