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The LINCKS system is made up of essentially four separate layers.
Going from the layer closest to the data storage, to the layer closest
to the user, the layers are the following:
- The NODE database layer
- The NODE workspace layer
- The Composition Management layer
- The interface layer
The basic architecture is a client server architecture, where the
database resides on a single server machine
and the
clients are on workstations connected to the server by a local area
network.
- Layer 1 (The NODE database layer) resides on the server machine
and is made up of three modules (monitor, dbs, and netserv)
which manage such things as attaching a workstation process to
a database, low-level retrieval and storage, and awareness of
parallel editing.
- Layer 2 (The NODE workspace layer) is encapsulated in the
LIBLINCKS library and works together with layer 1 to form the
basic object-centred database management system which we refer
to as NODE
.
NODE has previously been released separately
to a number of users. The NODE interface is a programmer's
interface only and is via the ``user functions'' in the
LIBLINCKS library.
The central data structure of the NODE subsystem is the
information component described earlier.
- Layer 3 filters out substructures in the database, so called
composite objects, and represents these as a finer grained
structure of items. The central data structure of this layer
is what we call the reference structure. The reference
structure consists of a template which gives the form of a
particular type of composite object, and the target which gives
the form of a particular instance of the template.
- Layer 4 displays the leaf items of the reference
structure in a window display. It provides the interface to
the editing of the reference structure and via that, the
information components. Editing of the leaf
items is done directly on the display using emacs-like
commands. Editing of the inner structure requires structure
editing commands, which are outside the scope of editors like
emacs.
Our goal is for layer 4 to be replaceable by modules relying on
different windowing systems (or even text terminals). However
the current version requires X Windows.
Next: Potential Uses of
Up: Overview of LINCKS
Previous: Bound and Unbound
Martin Sjolin
Mon May 29 19:53:45 MET DST 1995