Host/API 
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| Host/API | | HOST |
HOST is a set of FORTRANSIR/DBMS user to interface directly with a database. These routines provide
all the capabilities of a DBMS RETRIEVAL or RETRIEVAL UPDATE.
However, schema definition, schema modification, batch data input, retrieval procedures
(such as SPSS SAVE FILE or CONDESCRIPTIVE), utility routines and
the graphical user interface are not available via HOST. These operations
must be performed with DBMS.
HOST is designed for use in those situations in which features are required
that are not available in DBMS. It provides a direct interface between a database and a
user-written program. For this reason, HOST is particularly appropriate when
the user has an existing application package that requires the inclusion of facilities for
retrieval of information from a database. HOST also provides facilities that
give the SIR/DBMS user the capability to write a program that can process input from many
terminals. The user's program controls the operation of the terminals and uses
HOST to process one or more databases simultaneously, a feature not available
in DBMS.
The HOST package (like any subroutine package) must be used correctly and
carefully to avoid damage to the database. Unlike DBMS, the HOST routines
cannot protect the database from programmer error, accidental or deliberate. For example,
if a HOST memory resident table is modified in any way by the user-written
routines during a run, then invalid data, pointers, counts, and other erroneous
information may be written to the database. This invalid information may not be detected
by either HOST or DBMS until later.
We recommend that applications using HOST be tested thoroughly with a
duplicate of the database before the programs are put into production.
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