Section 2.6: DTD Viewers

Recently, as DTDs have increased in size and complexity, various software houses have developed DTD viewers. Most of these viewers provide facilities for editing the DTD, so assisting DTD writers in their task.


Product:
SGML Companion
Associated Products:
-
Developer:
Publishing Development AB (Sweden)
UK Supplier(s):
-
Price:
$500 with volume discounts
Platforms:
Microsoft Windows 3.1
Description:
SGML Companion creates and maintains DTDs and DTD collections. It is able to import element and attribute declarations. It shows the user the document structure graphically, either by tagname or by short descriptions. Being a windows/graphical environment it allows the building of DTDs by use of drag and drop. It can maintain DTDs containing all features of SGML except DATATAG, CONCUR, SUBDOC, and LINK.
Assessment:
This product is still in the course of development by a small company. Many of the features that have been advertised were not available on the `alpha' version demonstrated.


Product:
ZIFtech DTD Viewer
Associated Products:
-
Developer:
ZIFtech Computer Systems, Inc (Canada)
UK Supplier(s):
-
Price:
CA$150 (excl. shipping). Academic price: CA$82.50 (excl. shipping)
Platforms:
MS-Windows (can port to other platforms subject to demand)
Description:
The ZIFTech DTD Viewer gives a graphical representation of a DTD. It allows users to see the relationships between the document elements. All files and local changes composing the DTD are resolved. All parameter entities are resolved, and all parser supplied values are presented to the viewer. The DTD structures can be printed, providing a record for documenting and understanding new and existing DTDs. The system is coupled very closely to sgmls — the public domain SGML parser resident of the Exeter anonymous ftp server.


Product:
Near & Far
Associated Products:
CADE
Developer:
Microstar Software Ltd (Canada)
UK Supplier(s):
OMI Logistics Ltd
Price:
£3000 (academic discount available)
Platforms:
Windows 3.1, Unix (being developed)
Description:
Near & Far will create SGML DTDs graphically, re-engineer existing DTDs, and visualise and report on document structures represented by DTDs. It has a range of facilities to allow the user to work on very large DTDs by expanding and/or contracting models to any detail. It will validate DTDs once they have been produced. It will create and maintain a central library of tag and DTD fragments. The system provides extensive soft and hard copy reporting facilities including cross-references of attributes, entities, elements, and terminals. Graphical reports of any part of the document structure can be produced. Near & Far is part of a much larger total CADE groupware system.

Assessment:
Near & Far should be easy to use once you have got used to the basic concepts, and are able to use the mouse to a relatively high degree of accuracy. It provides the wide range of facilities that are required when designing and creating DTDs. It allows all major DTD features to be incorporated into a DTD — attributes, inclusions, exclusions (but see comments below). Other features (datatag, subdoc, link and concur) are not available. However ...

On the negative side: it provides no guidance for the beginner (using the status bar would have been straight-forward and of help to the beginner, but isn't used); there is no explanation that I could find for the different colours used to represent the elements; the documentation discusses `model' when it means `DTD' (I could not find anything about individual element models — the correct use of the term `model'); I found representation of bracketed parts of an element model confusing, particularly if that sub-model was a parameter entity (in the demonstration DTDs one parameter entity expands to `double- bracketed' elements in one element model and single-bracketed in another); layout can either be vertical or horizontal, but in neither format is the aspect ratio of the screen properly utilised. In short, I found it easier to read the printed demonstration DTDs than to view them graphically using Near & Far. I imagine Near & Far may come into its own with very large un-structured DTDs, but I was not able to assess this.

As a single package for the design and maintenance of a DTD library, Near & Far seems not to be value for money. As part of a large CADE system, it may be.