The Python HTMLgen Module

In my next example, I'll show you how a data stream can be processed to produce a series of documents that are interlinked. The script in Listing 3 creates a set of two documents summarizing all the Red Hat packages installed on a Linux system. The resulting HTML page is shown in Figure 3. An index document summarizes the RPM major groups, and a second main document summarizes the RPMs in each group. A link for each group in the index document jumps directly to each group's entries in the main document.

The HTML is generated from the output of the following rpm command:

rpm -q -a --queryformat \
   '%{group} %{name} %{summary}\n'

The output typically looks like this:

System/Base sh-utils GNU shell utilities.
Browser/WWW lynx tty WWW browser
Programming/Tools make GNU Make.
System/Library xpm X11 Pixmap Library
System/Shell pdksh Public Domain Korn Shell

I produce two documents, an index document (idoc), and a main document (mdoc), using HTMLgen's SeriesDocument to give both documents the same look-and-feel. By using a SeriesDocument, I can configure standard document headers, footers and navigation buttons via an rcfile and other optional arguments.

The index document (idoc) has only one HTMLgen component: an HTML list of RPM groups. I've used the HTMLgen.List columns option to create a multi-column list:

ilist = HTMLgen.List(style="compact", columns=3)
idoc.append(ilist)

The for loop processes each line from the rpm command and generates both idoc and mdoc text. Each time the group name changes, I add a new list entry to the ilist:

if group != lastgroup:
 lastgroup = group
 title = HTMLgen.Text(group)
 href = HTMLgen.Href(mainfile+"#"+ group,
        title)
 index.append(href)

<A HREF="rpmlist.html#Browser/FTP">Browser/FTP</A>

anchor = HTMLgen.Name(group, title)

mdoc.append(HTMLgen.Heading(2, anchor))

<H2><A NAME="Browser/FTP">Browser/FTP</A></H2>

grplist = HTMLgen.DefinitionList()

grplist.append(
 (HTMLgen.Text(name),HTMLgen.Text(summary)))

In this example, I simultaneously generated two simple documents and linked one to the other. This example could easily be extended to provide further links to individual documents for each RPM, and from each RPM to the RPMs it depends on.

I've only scratched the surface of what's possible with HTMLgen and Python. I haven't covered the HTMLgen objects for HTML Forms, Image Maps, Nested Tables, Frames, or Netscape Scripts. I also haven't made use of Python's object-oriented nature. For example, I could have sub-classed some of the HTMLgen objects to customize them for specifics of each application. I haven't discussed the Python module for CGI handling. You can read more about these topics by pointing your browser at some of the references accompanying the article (see Resources).

If you're trying to get started with HTMLgen, the HTMLtest.py file distributed with HTMLgen provides some good examples. The HTMLgen documentation is quite good, although in some cases, more examples would help. I don't think my examples require any particular distribution of Linux, libc or Python. All of them were written using HTMLgen 2.0 with Python 1.4 on Caldera OpenLinux Standard version 1.2.

Resources