A series of graphical user interfaces allows a user to define rules for parsing unstructured and structured log data and generate an aggregate rule to identify events across multiple lines of one or more log files. A first graphical user interface allows a user to select a line from a log file under analysis, search for matching lines in the log file, define rules for parsing the log file, and tokenize attributes of the selected lines. A second user interface allows the user to aggregate defined rules so that messages may be correlated to identify events that occur across multiple lines.