

VDL README  July 18, 1996  Last Modified Aug 23, 1999

VDL is the "Virtual Data Logger".  Basically it is all the code needed to send data
to the NEIC via a VSAT or TCP/IP socket except for the functions to acquire data to
process.  VDL is based on the NSN "FRONT" and "PASS" programs and fully implements
the NSN triggers, compression, and data management.   It is designed to user very
generic C code and to force all of the system/site dependent code to be in the
user supplied routines.

This software is provided free by the NSN, however, its support by the NSN is limited
to bug fixes periodically and new features sporadically added.  

For more information look at the comments at the beginning of the PASS.C and 
VDL.C routines.

TAR files :
vdl.tar.Z	compress source code and SCRIPTS and PARMS directories.
vdlida.tar.Z compressed source for a IDA/NRTS library
vdldatasock.tar.Z compressed source for running a vdl from a data sock (VDLUCB).

 
Changes /Updates

18 Jul 1996		First public released version.
15 Dec 1998		Updated version to deal with triggered data, more sources of data
				better control via command line proceedures, support for parameter
				files for multiple stations per invokation. 

				VDLUCB gets data through a UCB based DATASOCK/COMSERV.  See 
				documentation in comments of routine FEEDME.C. You need to 
				vdldatasock.tar.Z which contains the library for accessing datasock.

				VDLASL gets data from the LISS server at ASL (see makefile.asl and 
				FEEDME_SEED.C).

				VDL for earthworm gets its data directly from ADSEND (see 
				makefile.solew and FEED_VDL_EW.C).

				VDLIDA gets data from NRTS at the IDA network center (see VDLIDATAP.C
				and makefile.idahub).  You need the vdlida.tar.Z to get the 
				idatap-1.2.2 library used to access the NRTS.

				VDLRCV is a test version that runs VDL from a NSN RCV client.  So,
				NSN sends data to RCV which goes to VDL which goes back to the
				NSN (hopefully under and assumed name).  See FEEDME_RCV.C and 
				the primary makefile.

				VDLMOM is often used to watch over multiple VDLs.  It is controlled
				by the vdlmom.setup which contains the command lines needed to 	
				invoke one or more VDL children.  The children are define by 
				command lines in the vdlmom.setup in the directory at the time 
				VDLMOM is invoked.  

				At some sites the "chkvdlmom" script is started in cron to 
				periodically check that VDLMOM is running and to notify 
				Dave Ketchum by mail if it dies.  This routine might use genralized
				scripts in the SCRIPTS area or site specific ones.  The PARMS
				subdirectory contains the site specific files (normally params files
				for multistation VDLs).

				PSVDL* contain quick ps commands to look at a VDL processes.

Dave Ketchum
ketchum@usgs.gov
(303) 273-8479
