A method and system are provided. The method includes performing, by a logs-to-time-series converter, a logs-to-time-series conversion by transforming a plurality of heterogeneous logs into a set of time series. Each of the heterogeneous logs includes a time stamp and text portion with one or more fields. The method further includes performing, by a time-series-to-sequential-pattern converter, a time-series-to-sequential-pattern conversion by mining invariant relationships between the set of time series, and discovering sequential message patterns and association rules in the plurality of heterogeneous logs using the invariant relationships. The method also includes executing, by a processor, a set of log management applications, based on the sequential message patterns and the association rules.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method, comprising: performing, by a logs-to-time-series converter, a logs-to-time-series conversion by transforming a plurality of heterogeneous logs into a set of time series, wherein each of the heterogeneous logs includes a time stamp and text portion with one or more fields; performing, by a time-series-to-sequential-pattern converter, a time-series-to-sequential-pattern conversion by mining invariant relationships between the set of time series, and discovering sequential message patterns and association rules in the plurality of heterogeneous logs using the invariant relationships; and executing, by a processor, a set of log management applications, based on the sequential message patterns and the association rules. 2. The method of claim 1, wherein performing the logs-to-time-series conversion comprises: performing automatic log format recognition on the plurality of heterogeneous logs; and performing a per-format time series generation to generate, as the set of times series, a respective time series for each of a plurality of different log formats recognized by the automatic log format recognition. 3. The method of claim 2, wherein performing the automatic log format recognition comprises: applying a similarity measurement to the plurality of heterogeneous logs; applying a log hierarchical clustering algorithm to the plurality of heterogeneous logs, and using results of the similarity measurement, to generate and output a log cluster hierarchy comprising a plurality of different cluster levels; conducting a log motif discovery on the plurality of heterogeneous logs to find a set of pattern representative layouts; and back propagating up, from lower levels to higher levels in the log cluster hierarchy, information for the set of pattern representative layouts, to provide a set of format pattern representations. 4. The method of claim 3, wherein the similarity measurement leverages log layout information and log content information for the plurality of heterogeneous logs. 5. The method of claim 3, wherein performing the automatic log format recognition further comprises generating semantic tokens from the plurality of heterogeneous logs. 6. The method of claim 2, wherein performing the per-format time series generation comprises, for each of the plurality of different log formats in the log cluster hierarchy: finding a time period that any of the plurality of heterogeneous logs cover, based on time stamps in messages in the plurality of heterogeneous logs; dividing the time period into intervals of length L; creating, for each time interval, a message frequency counter for each of the plurality of different formats; for each of the messages in the plurality of heterogeneous logs that matches any of the plurality of different log formats, finding a time interval that a time stamp for the message falls into, and increasing a corresponding message frequency counter for a corresponding one of the plurality of different log formats by 1; and outputting the respective time series for each of the plurality of different log formats. 7. The method of claim 6, wherein the respective time series for each of the plurality of different log formats is in a form of ((time interval 1, frequency counter 1), (time interval 2, frequency counter 2), . . . ). 8. The method of claim 6, wherein a noise format is used for the messages in the heterogeneous logs that do not match any of the formats in the clustering hierarchy. 9. The method of claim 1, wherein performing the time-series-to-sequential-pattern conversion comprises mining invariant relationships in the time series; mapping the invariant relationships into log format correlation relationships to determine correlated log format sets; and discovering sequential patterns in the correlated format sets. 10. The method of claim 9, wherein mining the invariant relationships comprises learning relationships between message frequency measurements using AutoRegressive models with eXogenous inputs. 11. The method of claim 9, wherein mapping the invariant relationships into the log format correlation relationships comprises building an invariant graph having nodes representing log formats, and wherein the correlated format sets are determined based on relationships in the invariant graph. 12. The method of claim 9, wherein discovering the sequential patterns in the correlated format sets comprises: creating an ordered event list E; for each message x in the plurality of heterogonous logs matching any format f in the correlated format set, generating an event (time(x), format(x)), inserting the event into the list E, and ordering the event in the list E by the time stamp in the log message x; discovering format sequential patterns in the resulting ordered event list E; and outputting the format sequential patterns, along with the correlated format set as an association rule. 13. A non-transitory computer program product for discovery of message ordering invariants in a plurality of heterogeneous logs, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a computer to cause the computer to perform a method comprising: performing, by a logs-to-time-series converter, a logs-to-time-series conversion by transforming a plurality of heterogeneous logs into a set of time series, wherein each of the heterogeneous logs includes a time stamp and text portion with one or more fields; performing, by a time-series-to-sequential-pattern converter, a time-series-to-sequential-pattern conversion by mining invariant relationships between the set of time series, and discovering sequential message patterns and association rules in the plurality of heterogeneous logs using the invariant relationships; and executing, by a processor, a set of log management applications, based on the sequential message patterns and the association rules. 14. The non-transitory computer program product of claim 13, wherein performing the logs-to-time-series conversion comprises: performing automatic log format recognition on the plurality of heterogeneous logs; and performing a per-format time series generation to generate, as the set of times series, a respective time series for each of a plurality of different log formats recognized by the automatic log format recognition. 15. The non-transitory computer program product of claim 14, wherein performing the automatic log format recognition comprises: applying a similarity measurement to the plurality of heterogeneous logs; applying a log hierarchical clustering algorithm to the plurality of heterogeneous logs, and using results of the similarity measurement, to generate and output a log cluster hierarchy comprising a plurality of different cluster levels; conducting a log motif discovery on the plurality of heterogeneous logs to find a set of pattern representative layouts; and back propagating up, from lower levels to higher levels in the log cluster hierarchy, information for the set of pattern representative layouts, to provide a set of format pattern representations. 16. The non-transitory computer program product of claim 15, wherein the similarity measurement leverages log layout information and log content information for the plurality of heterogeneous logs. 17. The non-transitory computer program product of claim 13, wherein performing the time-series-to-sequential-pattern conversion comprises: mining invariant relationships in the time series; mapping the invariant relationships into log format correlation relationships to determine correlated log format sets; and discovering sequential patterns in the correlated format sets. 18. The non-transitory computer program product of claim 17, wherein mapping the invariant relationships into the log format correlation relationships comprises building an invariant graph having nodes representing log formats, and wherein the correlated format sets are determined based on relationships in the invariant graph. 19. The non-transitory computer program product of claim 17, wherein discovering the sequential patterns in the correlated format sets comprises: creating an ordered event list E; for each message x in the plurality of heterogonous logs matching any format f in the correlated format set, generating an event (time(x), format(x)), inserting the event into the list E, and ordering the event in the list E by the time stamp in the log message x; discovering format sequential patterns in the resulting ordered event list E; and outputting the format sequential patterns, along with the correlated format set as an association rule. 20. A system, comprising: a logs-to-time-series converter for performing a logs-to-time-series conversion by transforming a plurality of heterogeneous logs into a set of time series, wherein each of the heterogeneous logs includes a time stamp and text portion with one or more fields; a time-series-to-sequential-pattern converter for performing a time-series-to-sequential-pattern conversion by mining invariant relationships between the set of time series, and discovering sequential message patterns and association rules in the plurality of heterogeneous logs using the invariant relationships; and a processor for executing a set of log management applications, based on the sequential message patterns and the association rules.