Architecture Overview

This document describes the architecture of the whole system, and shows examples of the types of data that flows between the different components of the system. The following figure shows the architecture of the system.

Architecture Figure

The SGML document and the DTD are parsed by the public domain parser which produces the tree structure in a temporary form. This structure is then parsed by the parser module to create the internal parse tree representation. This structure is made persistent through Exodus and the E programming language. The following shows an instance of this method.

Example of a DTD and SGML Source:

  1. DTD: The following is a dtd, say foo.dtd.
    <!ELEMENT   BOOK    - -  (LINE)+>
<!ELEMENT LINE - -    (#PCDATA)>
  2. SGML Document: The following is an SGML document over the above DTD.
    <!DOCTYPE BOOK SYSTEM "foo.dtd">
<BOOK><LINE>This is the first line</LINE>
<LINE>This is the last line</LINE></BOOK>

The above two documents are passed to SGMLS, which produces the parsed output in a temporary form, that looks like the following:

(BOOK
(LINE
-This is the first line
)LINE
(LINE
-This is the last line
)LINE
)BOOK

This output is then processed by the parser module to create the internal parse tree structure.

Last updated on: 5/3/95