=head1 NAME
Html2Wml -- Program that can convert HTML pages to WML pages
=for html
<style type="text/css"> BODY { background-color: white; } .copyright { font-style: italic; } TABLE.note { border: 0px; } .note TH { background-color: #CCCCCC; } .note TD { background-color: #DDDDDD; } </style>
=head1 SYNOPSIS
Html2Wml can be used as either a shell command:
$ html2wml file.html
or as a CGI:
/cgi-bin/html2wml.cgi?url=/index.html
In both cases, the file can be either a local file or a URL.
=head1 DESCRIPTION
Html2Wml converts HTML pages to WML decks, suitable for being viewed on a
Wap device. The program can be launched from a shell to statically convert
a set of pages, or as a CGI to convert a particular (potentially dynamic)
HTML resource.
Althought the result is not guarantied to be valid WML, it should be the
case for most pages. Good HTML pages will most probably produce valid
WML decks. To check and correct your pages, you can use W3C's softwares:
the I<HTML Validator>, available online at http://validator.w3.org
and I<HTML Tidy>, written by Dave Raggett.
Html2Wml provides the following features:
=over 4
=item *
translation of the links
=item *
limitation of the cards size by splitting the result into several cards
=item *
inclusion of files (similar to the SSI)
=item *
compilation of the result (using the WML Tools, see L<"LINKS">)
=item *
a debug mode to check the result using validation functions
=back
=head1 OPTIONS
Please note that most of these options are also available when calling
Html2Wml as a CGI. In this case, boolean options are given the value
"1" or "0", and other options simply receive the value they
expect. For example, C<--ascii> becomes C<?ascii=1> or C<?a=1>. See the
file F<t/form.html> for an example on how to call Html2Wml as a CGI.
=head2 Conversion Options
=over 4
=item -a, --ascii
When this option is on, named HTML entities are converted to US-ASCII
characters using the same 7 bit approximations as Lynx. For example,
C<©> is translated to "(c)", and C<ß> is translated to "ss".
This option is off by default.
=item --collapse, --nocollapse
This option tells Html2Wml to collapse redundant whitespaces,
tabulations, carriage returns, lines feeds and empty paragraphs. The aim
is to reduce the size of the WML document as much as possible. Collapsing
empty paragraphs is necessary for two reasons. First, this avoids empty
screens (and on a device with only 4 lines of display, an empty screen can
be quite ennoying). Second, Html2wml creates many empty paragraphs when
converting, because of the way the syntax reconstructor is programmed.
Deleting these empty paragraphs is necessary like cleaning the kitchen :-)
If this really bother you, you can desactivate this behaviour with the
B<--nocollapse> option.
=item -c, --compile
Setting this option tells Html2Wml to use the compiler from WML Tools
to compile the WML deck. If you want to create a real Wap site, you should
seriously use this option in order to reduce the size of the WML decks.
Remember that Wap devices have very little amount of memory. If this is
not enought, use the splitting options.
=item --ignore-images
This option tells Html2Wml to completly ignore all image links.
=item --img-alt-text, --noimg-alt-text
This option tells Html2Wml to replace the image tags with their
corresponding alternative text (as with a text mode web browser).
This option is on by default.
=item --linearize, --nolinearize
This option is on by default. This makes Html2Wml flattens the HTML
tables (they are linearized), as Lynx does. I think this is better than
trying to use the native WML tables. First, they have extremely limited
features and possibilities compared to HTML tables. In particular, they
can't be nested. In fact this is normal because Wap devices are not
supposed to have a big CPU running at some zillions-hertz, and the
calculations needed to render the tables are the most complicated and
CPU-hogger part of HTML.
Second, as they can't be nested, and as typical HTML pages heavily use
imbricated tables to create their layout, it's impossible to decide which
one could be kept. So the best thing is to keep none of them.
B<[Note]> Although you can desactivate this behaviour, and although
there is internal support for tables, the unlinearized mode has not
been heavily tested with nested tables, and it may produce unexpected
results.
=item -n, --numeric-non-ascii
This option tells Html2wml to convert all non-ASCII characters to
numeric entities, i.e., C<©> becomes C<©>, and C<ß>
becomes C<ß>. By default, this option is off.
=item -p, --nopre
This options tells Html2Wml not to use the C<E<lt>preE<gt>>
tag. This option was added because the compiler from WML Tools 0.0.4
doesn't support this tag.
=item -o, --output
Use this option (in shell mode) to specify an output file.
By default, Html2Wml prints the result to standard output.
=back
=head2 Link Reconstruction Options
=over 4
=item --hreftmpl=I<TEMPLATE>
This options sets the template that will be used to reconstruct the
C<href>-type links. See L<"LINKS RECONSTRUCTION"> for more information.
=item --srctmpl=I<TEMPLATE>
This option sets the template that will be used to reconstruct the
C<src>-type links. See L<"LINKS RECONSTRUCTION"> for more information.
=back
=head2 Splitting Options
=over 4
=item -s, --max-card-size=I<SIZE>
This option allows you to limit the size (in bytes) of the generated
cards. Default is 1,500 bytes, which should be small enought to be loaded
on most Wap devices. See L<"DECK SPLITTING"> for more information.
=item -t, --card-split-threshold=I<SIZE>
This option sets the threshold of the split event, which can occur
when the size of the current card is between C<max-card-size> -
C<card-split-threshold> and C<max-card-size>. Default value is
50. See L<"DECK SPLITTING"> for more information.
=item --next-card-label=I<STRING>
This options sets the label of the link that points to the next card.
Default is "[>>]", which whill be rendered as "[E<gt>E<gt>]".
=item --prev-card-label=I<STRING>
This options sets the label of the link that points to the previous card.
Default is "[<<]", which whill be rendered as "[E<lt>E<lt>]".
=back
=head2 Debugging Options
=over 4
=item -d, --debug[=I<LEVEL>]
This option activates the debug mode. This prints the output result
with line numbering and with the result of the XML check. If the WML
compiler was called, the result is also printed in hexadecimal an ascii
forms. When called as a CGI, all of this is printed as HTML, so that can
use any web browser for that purpose.
=item --xmlcheck
When this option is on, it send the WML output to XML::Parser to check
its well-formedness.
=back
=head1 DECK SLICING
The I<deck slicing> is a feature that Html2Wml provides in order to
match the low memory capabilities of most Wap devices. Many can't handle
cards larger than 2,000 bytes, therefore the cards must be sufficiently
small to be viewed by all Wap devices. To achieve this, you should compile
your WML deck, which reduce the size of the deck by 50%, but even then your
cards may be too big. This is where Html2Wml comes with the deck slicing
feature. This allows you to limit the size of the cards, currently only
I<before> the compilation stage.
=head2 Slice by cards or by decks
On some Wap phones, slicing the deck is not sufficient: the WLM browser
still tries to download the whole deck instead of just picking one
card at a time. A solution is to slice the WML document by decks.
See the figure below.
_____________ _____________
| deck | | deck #1 |
| _________ | | _________ |
| | card #1 | | | | card | |
| |_________| | | |_________| |
| _________ | |_____________|
| | card #2 | |
| |_________| | . . .
| _________ |
| | ... | | _____________
| |_________| | | deck #n |
| _________ | | _________ |
| | card #n | | | | card | |
| |_________| | | |_________| |
|_____________| |_____________|
WML document WML document
sliced by cards sliced by decks
What this means is that Html2Wml generates several WML documents.
In CGI mode, only the appropriate deck is sent, selected by the id
given in parameter. If no id was given, the first deck is sent.
=head2 Note on size calculation
Currently, Html2Wml estimates the size of the card on the fly, by
summing the length of the strings that compose the WML output, texts and
tags. I say "estimates" and not "calculates" because computing the exact
size would require many more calculations than the way it is done now.
One may objects that there are only additions, which is correct, but knowing
the I<exact> size is not necessary. Indeed, if you compile the WML, most of
the strings of the tags will be removed, but not all.
For example, take an image tag:
C<E<lt>img src="images/dog.jpg" alt="Photo of a dog"E<gt>>.
When compiled, the string C<"img"> will be replaced by a one byte value.
Same thing for the strings C<"src"> and C<"alt">, and the spaces, double
quotes and equal signs will be stripped. Only the text between double quote
will be preserved... but not in every cases.
Indeed, in order to go a step further, the compiler can also encode
parts of the arguments as binary. For example, the string C<"http://www.">
can be encoded as a single byte (C<8F> in this case). Or, if the attribute
is C<href>, the string C<href="http://> can become the byte C<4B>.
As you see, it doesn't matter to know exactly the size of the textual
form of the WML, as it will always be far superior to the size of the
compiled form. That's why I don't count all the characters that may be
actually written.
Also, it's because I'm quite lazy ;-)
=head2 Why compiling the WML deck?
If you intent to create real WML pages, you should really
consider to always compile them. If you're not convinced, here is an
illustration.
Take the following WML code snipet:
<a href='http://www.yahoo.com/'>Yahoo!</a>
It's the basic and classical way to code an hyperlink. It takes 42 bytes
to code this, because it is presented in a human-readable form.
The WAP Forum has defined a compact binary representation of WML in its
specification, which is called "compiled WML". It's a binary format,
therefore you, a mere human, can't read that, but your computer can. And
it's much faster for it to read a binary format than to read a textual
format.
The previous example would be, once compiled (and printed here as
hexadecimal):
1C 4A 8F 03 y a h o o 00 85 03 Y a h o o ! 00 01
This only takes 20 bytes. Half the size of the human-readable form.
For a Wap device, this means both less to download, and easier things
to read. Therefore the processing of the document can be achieved in
a short time compared to the tectual version of the same document.
There is a last argument, and not the less important: many Wap devices
only read binary WML.
=head1 ACTIONS
Actions are a feature similar to (but with far less functionalities!) the
SSI (Server Side Includes) available on good servers like Apache. In order
not to interfere with the real SSI, but to keep the syntax easy to learn,
it differs in very few points.
=head2 Syntax
Basically, the syntax to execute an action is:
<!-- [action param1="value" param2='value'] -->
Note that the angle brackets are part of the syntax. Except for that
point, Actions syntax is very similar to SSI syntax.
=head2 Available actions
Currently, only two actions are available, but more can be implemented
on request.
=over 4
=item include
=over 8
=item Description
Includes a file in the document at the current point. Please note
that Html2Wml doesn't check nor parse the file, and if the file
cannot be found, will silently die (this is the same behavior as SSI).
=item Parameters
C<virtual=url> -- The file is get by http.
C<file=path> -- The file is read from the local disk.
=item Notes
If you use the file parameter, an absolute path is recommend.
=back
=item fsize
=over 8
=item Description
Returns the size of a file at the current point of the document.
=item Parameters
C<virtual=url> -- The file is get by http.
C<file=path> -- The file is read from the local disk.
=item Notes
If you use the file parameter, an absolute path is recommend.
=back
=back
=head2 Examples
If you want to share a navigation bar between several WML pages, you can
include it this way:
<!-- [include virtual="nav.wml"] -->
Of course, you have to write this navigation bar first :-)
=head1 LINKS RECONSTRUCTION
The links reconstruction engine is IMHO the most important part of
Html2Wml, because it's this engine that allows you to reconstruct the
links of the HTML document being converted. It has two modes, depending
upon whether Html2Wml was launched from the shell or as a CGI.
When used as a CGI, this engine will reconstructs the links of the HTML
document so that all the urls will be passed to Html2Wml in order to
convert the pointed files (pages or images). This is completly automatic
and can't be customized for now (but I don't think it would be really
useful).
When used from the shell, this engine reconstructs the links with the
given templates. Note that absolute URLs will be left untouched. The
templates can be customized using the following syntax.
=head2 Templates
=over 4
=item HREF Template
This template controls the reconstruction of the C<href> attribute of
the C<A> tag. Its value can be changed using the B<--hreftmpl> option.
Default value is
C<"{FILEPATH}{FILENAME}{$FILETYPE =~ s/s?html?/wml/o; $FILETYPE}">.
=item Image Source Template
This template controls the reconstruction of the C<src> attribute of
the C<IMG> tag. Its value can be changed using the B<--srctmpl> option.
Default value is
C<"{FILEPATH}{FILENAME}{$FILETYPE =~ s/gif|png|jpe?g/wbmp/o; $FILETYPE}">
=back
=head2 Syntax
The template is a string that contains the new URL. More precisely, it's
a Text::Template template. Parameters can be interpolated as a constant
or as a variable. The template is embraced between curcly bracets, and can
contain any valid Perl code.
The simplest form of a template is C<{I<PARAM>}> which just returns the
value of I<PARAM>. If you want to do something more complex, you can use
the corresponding variable; for example C<{"foo $I<PARAM> bar"}>, or
C<{join "_", split " ", I<PARAM>}>.
You may read L<Text::Template> for more information on what is possible
within a template.
If the original URL contained a query part or a fragment part, then they
will be appended to the result of the template.
=head2 Available parameters
=over 4
=item URL
This parameter contains the original URL from the C<href> or C<src>
attribute.
=item FILENAME
This parameter contains the base name of the file.
=item FILEPATH
This parameter contains the leading path of the file.
=item FILETYPE
This parameter contains the suffix of the file.
=back
This can be resumed this way:
URL = http://www.server.net/path/to/my/page.html
------------^^^^ ----
| | \
| | \
FILEPATH FILENAME FILETYPE
Note that C<FILETYPE> contains all the extensions of the file, so if its name
is F<index.html.fr> for example, C<FILETYPE> contains "C<.html.fr>".
=head2 Examples
To add a path option:
{URL}$wap
Using Apache, you can then add a Rewrite directive so that URL ending with
C<$wap> will be redirected to Html2Wml:
RewriteRule ^(/.*)\$wap$ /cgi-bin/html2wml.cgi?url=$1
To change the extension of an image:
{FILEPATH}{FILENAME}.wbmp
=head1 CAVEATS
Currently, only the well-formedness of the resulting WML can be tested, not
its validity.
Inverted tags (like "<b>bold <i>italic</b></i>") may produce unexpected
results. But only bad softwares do bad stuff like this.
=head1 LINKS
=head2 Download
=over 4
=item Nutialand
This is the web site of the author, where you can find the archives of
all the releases of Html2Wml.
[ http://www.maddingue.org/techie/ ]
=item Html2Wml on SourceForge
This is the web site of the Html2Wml project, hosted by SourceForge.net.
All the stable releases can be downloaded from this site.
[ http://htmlwml.sourceforge.net/ ]
=back
=head2 Resources
=over 4
=item The WAP Forum
This is the official site of the WAP Forum. You can find some technical
information, as the specifications of all the technologies associated with
the WAP.
[ http://www.wapforum.org/ ]
=item WAP.com
This site has some useful information and links. In particular, it has
a quite well done FAQ.
[ http://www.wap.com/ ]
=item The World Wide Web Consortium
Altough not directly related to the Wap stuff, you may find useful
to read the specifications of the XML (WML is an XML application), and the
specifications of the different stylesheet languages (CSS and XSL), which
include support for low-resolution devices.
[ http://www.w3.org/ ]
=item MobiliX
This web site is dedicated to Mobile UniX systems. It leads you to a lot
of useful hands-on information about installing and running Linux and BSD on
laptops, PDAs and other mobile computer devices.
[ http://www.mobilix.org/ ]
=back
=head2 Programmers utilities
=over 4
=item HTML Tidy
This is a very handful utility which corrects your HTML files
so that they conform to W3C standards.
[ http://www.w3.org/People/Raggett/tidy ]
=item Kannel
Kannel is an open source Wap and SMS gateway.
A WML compiler is included in the distribution.
[ http://www.kannel.org/ ]
=item WML Tools
This is a collection of utilities for WML programmers. This include
a compiler, a decompiler, a viewer and a WBMP converter.
[ http://pwot.co.uk/wml/ ]
=back
=head2 WML browsers and Wap emulators
=over 4
=item Opera 5.0
Opera is originaly a Web browser, but the version 5 has a good support
for XML and WML. Opera is available for free for several systems.
[ http://www.opera.com/ ]
=item wApua
wApua is an open source WML browser written in Perl/Tk.
It's easy to intall and to use. Its support for WML is incomplete,
but sufficient for testing purpose.
[ http://fsinfo.cs.uni-sb.de/~abe/wApua/ ]
=item Tofoa
Tofoa is an open source Wap emulator written in Python.
Its installation is quite difficult, and its incomplete WML support
makes it produce strange results, even with valid WML documents.
[ http://tofoa.free-system.com/ ]
=item EzWAP
EzWAP, from EZOS, is a commercial WML browser freely available for
Windows 9x, NT, 2000 and CE. Compared to others Windows WML browsers,
it requires very few resources, and is quite stable. Its support for
the WML specs seems quite complete. A very good software.
[ http://tofoa.free-system.com/ ]
=item Deck-It
Deck-It is a commercial Wap phone emulator, available for Windows and
Linux/Intel only. It's a very good piece of software which really
show how WML pages are rendered on a Wap phone, but one of its
major default is that it cannot read local files.
[ http://www.pyweb.com/php/test_adapt.php3 ]
=item WinWAP
WinWAP is a commercial Wap browser, freely available for Windows.
[ http://www.winwap.org/ ]
=item QWmlBrowser
QWmlBrowser (formerly known as WML BRowser) is an open source
WML browser, written using the Qt toolkit.
[ http://www.wmlbrowser.org/ ]
=item WAPreview
WAPreview is a Wap emulator written in Java. As it uses an HTML
based UI and needs a local web proxy, it runs quite slowly.
[ http://wapreview.sourceforge.net ]
=item J2Wap
This is a Wap emulator written in Java. It uses the Java native
GUI, and claims to support binary WML, but it doesn't seem to work
at all at this time.
[ http://j2wap.sourceforge.net ]
=back
=head1 ACKNOWLEDGEMENTS
Werner Heuser, for his numerous ideas, advices and his help for the debugging
Igor Khristophorov, for his numerous suggestions and patches
And all the people that send me bug reports: Daniele Frijia, Axel Jerabek
=head1 AUTHOR
SE<eacute>bastien Aperghis-Tramoni <maddingue@free.fr>
=for html
<hr /><div class="copyright">
=head1 COPYRIGHT
Copyright (c)2000, 2001 SE<eacute>bastien Aperghis-Tramoni
This program is free software. You can redistribute it and/or modify it
under the terms of the GNU General Public License, version 2 or later.
=for html
</div>
=cut