Glossary of Shore Terms
The Shore Project Group
Computer Sciences Department
- anonymous object
A Shore object that does not have
a name in the Shore name space.
- cross reference
An object whose contents are a serial number.
A cross reference has no analog in Unix.
Shore's analog of a Unix directory.
A directory is a Shore object.
A file is a Storage Manager concept.
A file is a area on a disk in which records are created.
In a sense, it is a home for an object.
Files have certain properties that control how their
updates are logged and whether records within the files are
- file system
The Unix-like hierarchy of objects that
resides on a volume.
A file system may be linked to other file systems
in the global Shore name space by way of a
A frozen interface (type) cannot be changed, and
therefore can have instances.
A type is frozen by freezing the module that contains it.
Freezing modules is done by the SDL editing programs
A persistent mapping of keys to values:
may be a B-tree, R-tree, or any other index type supported
by the SSM.
An index is not an object.
It is an attribute of an object, if it is a manual index.
It is embedded in a set (an attribute
of an object), if it is an automatic index.
In SDL, the construct that describes a complete
abstract data type,
of which instances (objects) can be created.
- language binding
The SDL language binding, i.e., the source code
generated by an SDL compiler.
- See language binding.
Shore's analog of a Unix hard link.
- metatype object
Objects that are part of the type system, but which cannot be instantiated
directly by users.
Metatype objects are combined in various ways by the Shore type
system to form types.
A pool whose contents are types and
Once a module is frozen, the types it contains can be
- mount point
Shore's analog of an AFS mount point:
a persistent, cross-volume, link to the root directory
of a volume.
A Shore object as seen by users of the SVAS, OC, or SDL.
An object is an instance of an abstract data type.
While the SVAS does not interpret the structure or abstract data type
of an object, it recognizes that an object has a type and system
- object cache
The component of the Shore software that caches objects in the
the application's address space.
See object cache.
- object identifier
An object identifier,
which is bit pattern that unambiguously
can identify an object.
OIDs can be logical or physical.
The SVAS deals only in logical OIDs.
In these documents,
OID is intended to mean logical OID
unless its alternative meaning is made explicit.
A logical OID consists of a volume ID and a serial number.
- See object identifier.
A Shore object that is associated with a file that
A pool is a registered object, whose contents identify the
file associated with the pool.
A Shore object as viewed by the SSM: an untyped
sequence of bytes, without system properties.
A reference is an SDL concept.
It is an abstract data type that
can be used to manipulate an object in the object cache.
- registered object
A Shore object that has a name in the Shore
- root volume
The volume on which the root file system is located.
- root file system
The file system whose root directory is ``/''.
- root directory
A highest directory in the hierarchy of directories
that composes a file system.
The root directory of exactly one file system is named
``/''; the root directories of other file systems
can be linked into the Shore name space
through mount points.
The Shore Data Language, a language for defining
abstract data types, from which source code can be generated
for various programming languages.
- serial number
A bit pattern that
can identify an SSM entity (record, file, or index)
within the context of
the volume on which the entity resides.
A serial number is not always associated with a Shore entity.
Serial numbers, once used to identify an entity, are never
used for any other purpose,
which means that if an entity is destroyed, its serial number is never
The SVAS and SSM enforce this rule; all value-added servers
should do the same.
- Shore Value-Added Server
The Shore Value-Added Server. The SVAS builds on the SSM to provide
applications with typed objects, a file system, and
access to data managed by the
This research is sponsored by
the Advanced Research Project Agency,
ARPA order number 018 (formerly 8230),
monitored by the U.S. Army Research Laboratory
under contract DAAB07-91-C-Q518.
- See storage manager.
- storage manager
The Storage Manager component of Shore. The SSM provides persistent
storage of untyped data and indexes by managing disks and caches
- See Shore Value-Added Server.
- symbolic link
Shore's analog of a Unix symbolic link.
A symbolic link is a Shore object.
- See system properties.
- system properties
A set of properties of each object, including
an owner, group, and a set of bits controlling
read, write, and execute access to the object,
size, and modification time.
These properties are analogous to the Unix
properties of directories and files.
- TEXT attribute
An optional attribute in an SDL interface
that is a sequence of uninterpreted, unsigned bytes,
and which serves to
contain the Unix-world's view of an instance of the interface.
An SDL interface can contain at most one TEXT attribute.
A sequence of Shore commands that
together have the ACID properties of a degree 0, 1, 2, or 3
transaction in the traditional transaction model.
An object or group of metatype objects
that describe abstract data types, which are visible to
Shore users and applications.
Such an abstract data type corresponds to
an SDL interface, and
can be instantiated as Shore objects.
- value-added server
A server that uses the Shore storage manager and possibly
the Shore Value-Added Server.
A physical device (e.g., a disk).
NB: in later versions, a volume will be an abstract concept;
it will not be tied to a device.
A volume may contain any number of files.
A volume may contain a logical OID index (q.v.).
All volumes that are used by the SVAS contain such an index,
which is described elsewhere.
- volume ID
A sequence of bits that identifies a volume.