Javadoc comments or equivalent in XSchema

Sun Jul 26 05:36:16 BST 1998

> From:          "Curt Arnold" <CurtA at worldnet.att.net>
> Date:          Sat, 18 Jul 1998 01:42:10 -0500

> I have been using some JavaDoc-like comments in my XML-Data
> definitions to automatically generate HTML documentation for the document
> content.  I have had my XML-Data to DTD converter modified to produce the
> HTML documentation at the same time as it builds the DTD.
> 
> Has any body else been doing anything in this area?

Yes, I've done something very similar, where I use a single file containing 
data that defines the schema/DTD, and includes documentation in addition to 
the declarations used by software. Actually, I'm not using xml (xml-data) to 
hold the definitions, but an equivalent ASCII format more suitable for hand 
editing and human reading (somwhat like RFC822 headers which can be trivially
reformatted into <tag>...</tag>).

The single data file is used to
1. Create the DTD and/or other definitions used by database software, 
defining element types/fields.
2. Create a formatted HTML file which serves as documentation on the schema.
3. Create an alternate form for documentation as 'help' containing 
instructions for data preparers. The generated help files contain href names 
for links in forms, etc.
4. Create WWW forms used for data entry and edits. Forms can show examples
for fields as a guide for entry.
5. Create javascript help (or helpfile links), so instructions appear in a 
help window frame when clicking in a field.

Unlike other approaches, all documentation and definitions specific to a 
schema/DTD are complete in this single source. There ares no separate 
(non-extracted) documentation files, misc notes in SGML comments, missing 
documentation, etc. common with other approaches.

For enumerated data types, the schema definition data file contains the 
values with documentation or else references enumerated values externally 
(with documentation). These definitions define the contents of a pull-down 
select list or radio/checkbox list in a form with brief 
definitions/instructions or links or javascript-based help. With many other 
database definitions, the enumerated values are often undefined and/or 
undocumented.

> I haven't been making a distinction between regular comments and processed
> comments and have only been using @see and @example formulations.  Between
> minimal comments and information in the schema, it is able to do a
> reasonably good job documenting how to use the schema.

As with javadoc, the documentation associated with a DTD shouldn't be a bunch 
of arbitrary HTML (IBTWSH) pages. The documentation for an element, etc. is 
specific kinds of text that is assembled into various kinds of documentation, 
not something normally read in isolation. Javadoc uses the @ notation to 
identify the semantics of the documentation text so it can format the content 
appropriately, including href links and names.

In XML, of course, <tags> would be used to mark the semantics of the 
documentation. In order to synthesize nicely readable HTML documentation and 
all the other kinds of extracted documentation such as that mentioned above, 
there needs to be a set of documentation elements defined. Failure to 
define an appropriate set of tags means that it won't be possible to create 
reasonable variants on types of documentation.

The <description> in xml-data is an example of the kind of semantic oriented 
(vs presentation) tags needed, and also an example of what is severly wrong 
with EDI and other typical database documentation-- incomplete inadequate 
documentation. The examples of the xml-data <description> are not really 
descriptions, but a few words more aptly called "title". Appropriate 
documentation requires much more than a few words.

I would be willing to write up a proposal for a set of elements useful in 
documentation, though it will have to be a week from now. Without thinking 
about it, the kinds of documentation elements I've used are something like:

<Title> A short (one line) descriptive title
Description: The title is a short description associated with a name or 
token, typically 1 line, which provides a more complete phrase than the 
single word name. The title might appear with the name in a table of 
contents, short summary reference, or 1 line comments found with declarations
in source code.

The title should be an alternative for the name or token not a duplicate. If 
no title other than the original name exists, it should be omitted rather 
than reentering the element or attribute name.

<Prompt> An human-oriented phrase serving as an alternative for a name
Description: The name used for elements, attributes, and tokens often 
contains abbreviations or other short notation that makes it more suited to 
use in software systems. A prompt provides an alternative for use in forms,
questionnaires, or other presentations of the data used by humans. 
Language specific alternatives for the name can be supplied using the prompt.

<Example> A sample data value illustrating the form and content
Description: An example serves as a simple means to illustrate the meaning of 
an elelemt or attribute, showing how data might be formatted and the 
appropriate content. The example might be included in documentation or on a 
data entry form. If more that one example is provided, the first one supplied 
should be the one selected when only a single example is shown, e.g. on a 
data entry form.

<Instructions> Detailed documentation written as preparer instructions
Description: The instructions form a detailed description and documentation 
for an element or attribute, but written in the narritive as might appear in 
help documentation or instrictions for filling out a form. This would 
typically suffice for documentation but is written in a style oriented for 
data preparars rather than programmers or readers.

<Description> Detailed documentation defining an element or attribute
Description: The description is a set of paragraphs providing a detailed 
definition and other documentation for an element or attribute. This could be 
used with the Instructions or as an alternative to Instructions. When used 
with Instructions, the Description should be used to provide more detail not 
normally of interest to data preparers, such as interpretation within 
database systems.

If the documentation is short, for example a phrase or sentence, then the 
Title should be used instead of Description.

--
Other tags such as the javadoc cross-referencing @ markers are also needed.

There are other tags needed that I don't have time to mention here. You might
have noticed some, e.g. with my use of "Title" and "Description" in the 
description above.

----

In contrast to tags marking the semantics of the parts of the documentation, 
use of certain presentation-oriented tags, e.g. <font> can cause serious 
problems. IBTWSH is a good basis, but I don't think all the tags in this set 
is appropriate for XSC documentation. Tags like <hr> should probably be 
banned. Tags like <big> and <small> should be banned. The usual use is 
something like "<big><b>Something</b></big><br>" because some author doesn't 
like the way Nescape spaces <h3>Something</h3>. The usual reason for <small> 
is to wrap everything, because some author thinks the font's are too big when 
view on his 21" monitor.

---

I think the goodt way to understand the requirements for documentation would 
be to write the XSC standard/specification in itself. I don't mean simply 
encode the DTD as XSC xml, I mean something equivalent to the whole set of 
HTML pages (or the complete xml-data document) should be represneted as XSC 
xml containing Doc elements. By processing the XSC-XSC, the XSC document 
(something similar to the current one) would be extracted including the 
appendix containing the DTD.

The usual case of a DTD plus some arbitrary side-file documentation means 
documentation is not reusable, not readily accessable, and often ambiguous or 
imcomplete. Specifying *complete* documentation within the xml-data or 
xml-xsc definition provides a single referenced file for the schema and in a 
reusable form. With distribiuted Internet applications based on the WWW, easy 
access and reuse of documentation (metadata) becomes more important. XSC 
documentation has the potential to solve this, but only if implemented 
properly.
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Carl Hage                                              C. Hage Associates
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<http://www.chage.com/chage/>                          Sunnyvale, CA 94086

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