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1. EVIO data files are read in and converted to LCIO events.
2. The HPS Java reconstruction is run to add physics object collections to the events, using a steering file such as EngineeringRun2015FullRecon.lcsim.
3. The events are written to an LCIO file containing results of the recon.
4. The recon LCIO file can be converted to ROOT DST Data Format.

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The HPS physics reconstruction is implemented in the HPS Java project as a chain of org.lcsim Drivers which process LCIO Data Format events that are accessed using the EventHeader API.  The driver list is described in an lcsim xml steering file which is configured by the lcsim job manager.  The production recon steering files are kept in this SVN folder and accessed as a class resource from a jar file rather than read from disk. 

The EVIO Data Format is converted into LCIO by an LCSimEventBuilder such as LCSimEngRunEventBuilder.  The EvioToLcio command line tool reads EvioEvents with an EvioReader and then uses an event builder to create LCIO events representing the raw data.  The driver chain is then run to perform the physics reconstruction which will add additional object collections to the event.  The combined events with the data and recon collections are written out to an LCIO file.  The LCIO output can be converted to ROOT DST Data Format for ROOT compatibility, or it may be loaded back into HPS Java for analysis. 

Steering Files

The production recon steering files such as EngineeringRun2015FullRecon.lcsim are kept in this SVN folder and accessed as a class resource from a jar file by the job manager. 

Data Conversion

The EvioToLcio utility converts EVIO to LCIO using an LCSimEventBuilder implementation such as LCSimEngRunEventBuilder.  The generated LCIO events are then optionally written to disk using an LCIODriver.  The physics reconstruction may also be run in the same process for efficiency.

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