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=head1 NAME

Html2Wml -- Program that can convert HTML pages to WML pages

=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 and non-ASCII characters are 
converted to US-ASCII characters using the same 7 bit approximations as 
Lynx. For example, C<&copy;> is translated to "(c)", and C<&szlig;> is 
translated to "ss". This option is off by default.  


=item --[no]collapse

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 --ignore-images

This option tells Html2Wml to completly ignore all image links. 


=item --[no]img-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 --[no]linearize

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., "E<eacute>" becomes C<&#233;>, and "E<szlig>" 
becomes C<&#223;>.  By default, this option is off. 


=item -p, --nopre

This options tells Html2Wml not to use the E<lt>preE<gt>
tag. This option was added because the compiler from WML Tools 0.0.4 
doesn't support this tag. 

=back


=head2 Links 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 SLICING"> 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 SLICING"> 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 "[&gt;&gt;]", 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 "[&lt;&lt;]", which whill be rendered as "[E<lt>E<lt>]". 

=back


=head2 HTTP Authentication

=over 4

=item -U, --http-user=I<USERNAME>

Use this option to set the username for an authenticated request. 

=item -P, --http-passwd=I<PASSWORD>

Use this option to set the password for an authenticated request. 

=back


=head2 Proxy Support

=over 4

=item -[no]Y, --[no]proxy

Use this option to activate proxy support. By default, proxy support 
is activated. See L<"PROXY SUPPORT">. 

=back


=head2 Output Options

=over 4

=item -k, --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. 

Take a look in F<wml_compilation/> for more information on how to use 
a WML compiler with Html2Wml. 


=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 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 WML 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 01 03 Y a h o o ! 00 01

This only takes 21 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

Only few actions are currently 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.

=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


=item skip

=over 8

=item Description

Skips everything until the first C<end_skip> action. 

=back


=back


=head2 Generic parameters

The following parameters can be used for any action. 

=over 4

=item for=I<output format>

This paramater restricts the action for the given output format. 
Currently, the only available format is "C<wml>" (when using C<html2chtml> 
the format is "C<chtml>"). 

=back


=head2 Examples

If you want to share a navigation bar between several WML pages, you can
C<include> it this way: 

    <!-- [include virtual="nav.wml"] -->

Of course, you have to write this navigation bar first :-)

If you want to use your current HTML pages for creating your WML pages, 
but that they contains complex tables, or unecessary navigation tables, 
etc, you can simply C<skip> the complex parts and keep the rest. 

    <body>
    <!--[skip for="wml"]-->
    unecessary parts for the WML pages
    <!--[end_skip]-->
    useful parts for the WML pages
    </body>


=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<{PARAM}> which just returns the 
value of PARAM. If you want to do something more complex, you can use 
the corresponding variable; for example C<{"foo $PARAM bar"}>, or 
C<{join "_", split " ", 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 PROXY SUPPORT

Html2Wml uses LWP built-in proxy support. It is activated by default, and 
loads the proxy settings from the environment variables, using the same 
variables as many others programs. Each protocol (http, ftp, etc) can be 
mapped to use a proxy server by setting a variable of the form C<PROTOCOL_proxy>. 
Example: use C<http_proxy> to define the proxy for http access, C<ftp_proxy> 
for ftp access. In the shell, this is only a matter of defining the variable. 

For Bourne shell: 

    $ export http_proxy="http://proxy.domain.com:8080/"

For C-shell: 

    % setenv http_proxy "http://proxy.domain.com:8080/"

Under Apache, you can add this directive to your configuration file: 

    SetEnv http_proxy "http://proxy.domain.com:8080"

but this has the default that another CGI, or another program, can use 
this to access external ressources. A better way is to edit Html2Wml and 
fill the option C<proxy-server> with the appropriate value. 


=head1 CAVEATS

Html2Wml tries to make correct WML documents, but the well-formedness and the 
validity of the document are not guarantied. 

Inverted tags (like "E<lt>bE<gt>bold E<lt>iE<gt>italicE<lt>/bE<gt>E<lt>/iE<gt>") 
may produce unexpected results. But only bad softwares do bad stuff like this. 



=head1 LINKS

=head2 Download

=over 4

=item Html2Wml

This is the web site of the Html2Wml project, hosted by SourceForge.net. 
All the stable releases can be downloaded from this site. 

[ http://www.html2wml.org/ ]

=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/softwares/ ]

=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 TuxMobil

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.tuxmobil.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

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 install 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://www.ezos.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/tools/ ]


=item Klondike WAP Browser

Klondike WAP Browser is a commercial WAP browser available for Windows 
and PocketPC. 

[ http://www.apachesoftware.com/ ]


=item WinWAP

WinWAP is a commercial Wap browser, freely available for Windows. 

[ http://www.winwap.org/ ]


=item WAPman

WAPman from EdgeMatrix, is a commercial WAP browser available for 
Windows and PalmOS. 

[ http://www.edgematrix.com/edge/control/MainContentBean?page=downloads ]


=item Wireless Companion

Wireless Companion, from YourWap.com, is a WAP emulator available 
for Windows. 

[ http://www.yourwap.com/ ]


=item Mobilizer

Mobilizer is a Wap emulator available for Windows and Unix. 

[ http://mobilizer.sourceforge.net/ ]


=item QWmlBrowser

QWmlBrowser (formerly known as WML BRowser) is an open source 
WML browser, written using the Qt toolkit. 

[ http://www.wmlbrowser.org/ ]


=item Wapsody

Wapsody, developed by IBM, is a freely available simulation 
environment that implements the WAP specification. It also 
features a WML browser which can be run stand-alone. 
As Wapsody is written in Java/Swing, it should work on any 
system. 

[ http://alphaworks.ibm.com/aw.nsf/techmain/wapsody ]


=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 PicoWap

PicoWap is a small WML browser made by three French students. 

[ http://membres.lycos.fr/picowap/ ]


=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, Ouyang


=head1 AUTHOR

SE<eacute>bastien Aperghis-Tramoni E<lt>sebastien@aperghis.net<gt>


=head1 COPYRIGHT

Copyright (C)2000, 2001, 2002 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. 


=cut