NAME¶
dacs.vfs - the
DACS virtual filestore
DESCRIPTION¶
These files are part of the
DACS suite.
The virtual filestore provides flexible ways for
DACS and software built
on top of
DACS to obtain information regardless of how or where the
information is stored. The
DACS core accesses (almost) all
configuration information through the virtual filestore layer, allowing
information to be more easily shared and maintained, secured, or organized for
better performance.
Sometimes it is easiest to store information in a regular file initially, where
it can be modified using an ordinary text editor, but after some growth a
database might improve performance. In some situations, accessing the
information remotely, via HTTP, makes administration more convenient or is
more secure. A goal of the virtual filestore is to make it simple to make
configuration choices appropriate to a particular
DACS environment, and
to change them as required. Consult
dacsvfs(1)[1] for additional
information.
For example, the account file used by
dacspasswd(1)[2] and other
components is accessed from within
DACS through the name passwds (a
string called an item type). The
DACS configuration in effect
determines how this is mapped to an object that contains the account
information, how an individual account name is looked up, and where the object
is located.
Each virtual filestore instance maps to either an uninterpreted sequence of
bytes (e.g., a Unix file or the output of a program) or an object that
contains zero or more items, each of which is associated with a key (i.e., the
name of an item relative in its virtual filestore context) and has an
uninterpreted sequence of bytes as its value (e.g., a database file, a Unix
file containing lines having a particular keyword/value structure, or a
directory containing regular files).
The
VFS[3] directive is used to specify where and how information is
stored. Some commands and functions take a VFS specification as an argument to
provide a default or override a default.
For maximum portability, a key should be composed of characters from the
Portable Filename Character Set[4]: any alphanumeric character, period,
hyphen, or underscore. The true limitation on the character set depends on the
underlying storage scheme and URI syntax constraints. There is no
a
priori limit on naming context or key length.
SEE ALSO¶
dacsvfs(1)[1],
dacs.conf(5)[5],
dacs.install(7)[6],
dacs_vfs(8)[7]
BUGS¶
AUTHOR¶
Distributed Systems Software (
www.dss.ca[8])
COPYING¶
Copyright2003-2012 Distributed Systems Software. See the
LICENSE[9] file
that accompanies the distribution for licensing information.
NOTES¶
- 1.
- dacsvfs(1)
- 2.
- dacspasswd(1)
- 3.
- VFS
- 4.
- Portable Filename Character Set
- 5.
- dacs.conf(5)
- 6.
- dacs.install(7)
- 7.
- dacs_vfs(8)
- 8.
- www.dss.ca
- 9.
- LICENSE