DataMuseum.dk

top - metrics - download

    Length: 3246 (0xcae)
    Types: TextFile
    Names: »objects.tex«

└─⟦3d0c2be1b⟧ Bits:30001254 ISODE-5.0 Tape
    └─⟦eba4602b1⟧ »./isode-5.0.tar.Z« 
        └─⟦d3ac74d73⟧ 
            └─⟦this⟧ »isode-5.0/doc/manual/objects.tex« 

TextFile

% run this through LaTeX with the appropriate wrapper

\f

\chapter	{The ISODE Objects Database}\label{isobjects}
The database \file{/usr/etc/isobjects} contains a simple mapping between
object descriptors and object identifiers.

The database itself is an ordinary ASCII text file containing information
regarding the known objects on the host.
Each line contains
\begin{itemize}
\item	the descriptor of the object, a simple string; and,

\item	the corresponding object identifier.
\end{itemize}

Blanks and/or tab characters are used to separate items.
All items after the first two are interpreted as an argument vector.
However,
double-quotes may be used to prevent separation between arguments in the
vector.
The sharp character (`\verb"#"') at the beginning of a line indicates a
commentary line.

\f

\section	{Accessing the Database}\label{isobject}
The \man libpsap(3) library contains the routines used to access the
database.
These routines ultimately manipulate an \verb"isobject" structure,
which is the internal form.
\begin{quote}\index{isobject}\small\begin{verbatim}
struct isobject {
    char          *io_descriptor;

    OIDentifier    io_identity;
};
\end{verbatim}\end{quote}
The elements of this structure are:
\begin{describe}
\item[\verb"io\_descriptor":] the object descriptor; and,

\item[\verb"io\_identity":] the object identifier.
\end{describe}

The routine \verb"getisobject" reads the next entry in the database,
opening the database if necessary.
\begin{quote}\index{getisobject}\small\begin{verbatim}
struct isobject *getisobject ()
\end{verbatim}\end{quote}
It returns the manifest constant \verb"NULL" on error or end-of-file.

The routine \verb"setisobject" opens and rewinds the database.
\begin{quote}\index{setisobject}\small\begin{verbatim}
int     setisobject (f)
int     f;
\end{verbatim}\end{quote}
The parameter to this procedure is:
\begin{describe}
\item[\verb"f":] the ``stayopen'' indicator,
if non-zero, then the database will remain open over subsequent calls to the
library.
\end{describe}
The routine \verb"endisobject" closes the database.
\begin{quote}\index{endisobject}\small\begin{verbatim}
int     endisobject ()
\end{verbatim}\end{quote}
Both of these routines return non-zero on success and zero otherwise.

There are two routines used to fetch a particular entry in the database.
The routine \verb"getisobjectbyname" maps object descriptors into
the internal form.
\begin{quote}\index{getisobjectbyname}\small\begin{verbatim}
struct isobject *getisobjectbyname (descriptor)
char   *descriptor;
\end{verbatim}\end{quote}
The parameter to this procedure is:
\begin{describe}
\item[\verb"descriptor":] the descriptor of the object.
\end{describe}
and returns the \verb"isobject" structure describing that object.
On failure, the manifest constant \verb"NULL" is returned instead.

The routine \verb"getisobjectbyoid" performs the inverse function.
\begin{quote}\index{getisobjectbyoid}\small\begin{verbatim}
struct isobject *getisobjectbyoid (oid)
OID     oid;
\end{verbatim}\end{quote}
The parameter to this procedure is:
\begin{describe}
\item[\verb"oid":] the identifier of the object.
\end{describe}
On a successful return,
an \verb"isobject" structure describing the object is returned.