NAME
Html2Wml -- Program that can convert HTML pages to WML pages
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.
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 *HTML Validator*,
available online at http://validator.w3.org and *HTML Tidy*,
written by Dave Raggett.
Html2Wml provides the following features:
* translation of the links
* limitation of the cards size by splitting the result into
several cards
* inclusion of files (similar to the SSI)
* compilation of the result (using the WML Tools, see the section
on "LINKS")
* a debug mode to check the result using validation functions
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, `--ascii' becomes `?ascii=1' or
`?a=1'. See the file t/form.html for an example on how to call
Html2Wml as a CGI.
Conversion Options
-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, `©' is translated to "(c)", and
`ß' is translated to "ss". This option is off by
default.
--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 --nocollapse option.
-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.
--ignore-images
This option tells Html2Wml to completly ignore all image
links.
--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.
--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.
[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.
-n, --numeric-non-ascii
This option tells Html2wml to convert all non-ASCII
characters to numeric entities, i.e., `©' becomes
`©', and `ß' becomes `ß'. By default, this
option is off.
-p, --nopre
This options tells Html2Wml not to use the `' tag. This
option was added because the compiler from WML Tools 0.0.4
doesn't support this tag.
-o, --output
Use this option (in shell mode) to specify an output file.
By default, Html2Wml prints the result to standard output.
Link Reconstruction Options
--hreftmpl=*TEMPLATE*
This options sets the template that will be used to
reconstruct the `href'-type links. See the section on "LINKS
RECONSTRUCTION" for more information.
--srctmpl=*TEMPLATE*
This option sets the template that will be used to
reconstruct the `src'-type links. See the section on "LINKS
RECONSTRUCTION" for more information.
Splitting Options
-s, --max-card-size=*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 the
section on "DECK SPLITTING" for more information.
-t, --card-split-threshold=*SIZE*
This option sets the threshold of the split event, which can
occur when the size of the current card is between `max-
card-size' - `card-split-threshold' and `max-card-size'.
Default value is 50. See the section on "DECK SPLITTING" for
more information.
--next-card-label=*STRING*
This options sets the label of the link that points to the
next card. Default is "[>>]", which whill be rendered
as "[>>]".
--prev-card-label=*STRING*
This options sets the label of the link that points to the
previous card. Default is "[<<]", which whill be
rendered as "[<<]".
Debugging Options
-d, --debug[=*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.
--xmlcheck
When this option is on, it send the WML output to
XML::Parser to check its well-formedness.
DECK SLICING
The *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
*before* the compilation stage.
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.
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
*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: `
'. When compiled, the string `"img"' will
be replaced by a one byte value. Same thing for the strings
`"src"' and `"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 `"http://www."' can
be encoded as a single byte (`8F' in this case). Or, if the
attribute is `href', the string `href="http://' can become the
byte `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 ;-)
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:
Yahoo!
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.
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.
Syntax
Basically, the syntax to execute an action is:
Note that the angle brackets are part of the syntax. Except for
that point, Actions syntax is very similar to SSI syntax.
Available actions
Currently, only two actions are available, but more can be
implemented on request.
include
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).
Parameters `virtual=url' -- The file is get by http.
`file=path' -- The file is read from the local disk.
Notes If you use the file parameter, an absolute path is
recommend.
fsize
Description Returns the size of a file at the current point of the
document.
Parameters `virtual=url' -- The file is get by http.
`file=path' -- The file is read from the local disk.
Notes If you use the file parameter, an absolute path is
recommend.
Examples
If you want to share a navigation bar between several WML pages,
you can include it this way:
Of course, you have to write this navigation bar first :-)
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.
Templates
HREF Template
This template controls the reconstruction of the `href'
attribute of the `A' tag. Its value can be changed using the
--hreftmpl option. Default value is
`"{FILEPATH}{FILENAME}{$FILETYPE =~ s/s?html?/wml/o;
$FILETYPE}"'.
Image Source Template
This template controls the reconstruction of the `src'
attribute of the `IMG' tag. Its value can be changed using
the --srctmpl option. Default value is
`"{FILEPATH}{FILENAME}{$FILETYPE =~ s/gif|png|jpe?g/wbmp/o;
$FILETYPE}"'
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 `{*PARAM'}* which just
returns the value of *PARAM*. If you want to do something more
complex, you can use the corresponding variable; for example
`{"foo $*PARAM' bar"}*, or `{join "_", split " ", *PARAM'}*.
You may read the Text::Template manpage for more information on
what is possible within a template.
If the original URL contained a query part or a fragment part,
then they will be appended to the result of the template.
Available parameters
URL This parameter contains the original URL from the `href' or
`src' attribute.
FILENAME
This parameter contains the base name of the file.
FILEPATH
This parameter contains the leading path of the file.
FILETYPE
This parameter contains the suffix of the file.
This can be resumed this way:
URL = http://www.server.net/path/to/my/page.html
------------^^^^ ----
| | \
| | \
FILEPATH FILENAME FILETYPE
Note that `FILETYPE' contains all the extensions of the file, so
if its name is index.html.fr for example, `FILETYPE' contains
"`.html.fr'".
Examples
To add a path option:
{URL}$wap
Using Apache, you can then add a Rewrite directive so that URL
ending with `$wap' will be redirected to Html2Wml:
RewriteRule ^(/.*)\$wap$ /cgi-bin/html2wml.cgi?url=$1
To change the extension of an image:
{FILEPATH}{FILENAME}.wbmp
CAVEATS
Currently, only the well-formedness of the resulting WML can be
tested, not its validity.
Inverted tags (like "bold italic") may produce
unexpected results. But only bad softwares do bad stuff like
this.
LINKS
Download
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/ ]
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/ ]
Resources
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/ ]
WAP.com
This site has some useful information and links. In
particular, it has a quite well done FAQ.
[ http://www.wap.com/ ]
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/ ]
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/ ]
Programmers utilities
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 ]
Kannel
Kannel is an open source Wap and SMS gateway. A WML compiler
is included in the distribution.
[ http://www.kannel.org/ ]
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/ ]
WML browsers and Wap emulators
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/ ]
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/ ]
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/ ]
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/ ]
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 ]
WinWAP
WinWAP is a commercial Wap browser, freely available for
Windows.
[ http://www.winwap.org/ ]
QWmlBrowser
QWmlBrowser (formerly known as WML BRowser) is an open
source WML browser, written using the Qt toolkit.
[ http://www.wmlbrowser.org/ ]
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 ]
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 ]
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
AUTHOR
Sébastien Aperghis-Tramoni
COPYRIGHT
Copyright (c)2000, 2001 Sébastien 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.