VDS(3)

NAME

     vds


     SYNOPSIS

     Virtual Data Set


     DESCRIPTION

     A vds is a data structure which contains information about a
     dataset  and  which  may also contain data.  The vds library
     provides operations to create a vds,  transform  its  struc-
     ture,  and  read  and  write data.  Using the vds library, a
     program can perform operations on an entire dataset  without
     having all the data in memory at one time.

     The  vds  library  is  concerned  mostly   with   conforming
     datasets, datasets which have requirements on file names and
     structure and on keywords.

     The intended operations to read datasets are a vds_open fol-
     lowed  by  vds_select*  operations,  followed  by vds_close.
     These  should  handle  both  conforming  and  non-conforming
     datasets.

     The intended operations to write datasets are a vds_new fol-
     lowed  by  vds_insert*  operations,  followed  by vds_close.
     These write only conforming datasets.

     Operations to transform structures and flush data  are  used
     in some cases.

     The type of a conforming dataset is indicated by the keyword
     CONFORMS  in its overview file.  The vds library handles the
     following  conformance  names.   These  are  enumerated   in
     soi_vds.h and named in vds_attrs.c
               TS
               TS_EQ
               TS_BLOCKED
               L_NU
               MDICAL
               MISC

     The external representations of conforming datasets are also
     enumerated  in  soi_vds.h  and  named in vds_attrs.c.  These
     describe the way that data  and  attributes  are  stored  in
     files,  external  to  the  vds  structure.   vds_open should
     deduce the external  representation.  The  call  to  vds_new
     specifies   the   external   representation.   The  external
     representation names are:
               CDF
               FITS
               FITS_MERGE
               FITS_TABLE
               RDB

     The internal representations of datasets are  enumerated  in
     soi_vds.h.  The types are:
               VDS_CDF_INTERNAL
               VDS_FILE
               VDS_CUBE
               VDS_FILES



     SEE ALSO

     The following sources include man pages for vds  operations,
     examples  of  dataset  names,  data name syntax and descrip-
     tions, and a description of conforming datasets.

     ~soi/CM/man/man3/vds*
     ~soi/CM/man/man1/modules.1
     ~soi/CM/src/libast.d/ReadMe
     http://soi.stanford.edu/sssc/dataset_descr/conforms.html


     FILES

     ~soi/CM/include/soi_vds.h
     ~soi/CM/src/libvds.d/*


     BUGS

     Yes


     RESTRICTIONS

     Not all combinations of  external  and  internal  types  are
     implemented.  Multi variables are not supported.

     Not all man pages exist.



     PLANNED IMPROVEMENTS

     See bugs and restrictions.