The input channel to read arbitrary ADAMO input is named GENE. Through this channel HEP can in princple read in any ADAMO[] database either from a GAF or a DAD[] connection. The generic procedure is to read several records of the same type and perform the same action on every record in a loop. This requires the records to be of identical type. All the internal histogramming described below (internal histogramming) works only if the record structure does not change. For DAD connections this provided by the concept of DAD.
In GAFs the structure of the records can change. In this case the looping has to check for each record which record type was loaded. This can be done in user written subroutines (COMIS or HEPM application).
HEP was originally designed to read HERMES Monte Carlo data (dataflow mcEvents) and/or reconstructed data (rcEvents). Files with these dataflows should be read either one type at a time or both in parallel. When reading both files in parallel the events have to be sychronized, since not every Monte Carlo event gives a recostructed event.
For this purpose two input channels were foreseen. These are named EVEN and RECO. These two channels are dedicated to these two specific dataflows.
The HERMES geometry data are necessary input in almost every processing of HERMES data. Therefore this geometry dataflow is loaded when the INIT command is executed. The source for this dataflow (DAD connection or file) can be specified as GEOM with the NAME command.
At startup time HEP tries to find the default source. It searches for the dadinit.cnf file on the default search path and tries to extract the adress of the geometry server from it. If this file is not found, HEP searches for the file hmcdg.ie in its default search path. If none of these searches succeeds, the destination is left empty. In this case the source has to be specified by the user. If the geometry cannot be loaded, INIT fails.
The internal name for this source is HBDF. The GAF loaded through this channel must contain the HbookDefs dataflow, which contains definitions for the internal histogramming. This data is also loaded at the INIT stage of HEP. To skip reading that data, the name must be empty.
When DAD connection for CMDS is specified, HEP will accept commands form the online server during looping. In SLAVE mode, HEP can totally be controllend by the server.