Torsten Förtsch

NAME

Apache2::PodBrowser - show your POD in a browser

DESCRIPTION

Yet another mod_perl2 handler to view POD in a HTML browser. See "HISTORY" for more information.

Direct Mode

Apache2::PodBrowser can run in direct and perldoc modes. In direct mode apache takes care of the URI to filename translation. So, $r->filename points to a regular file when the request hits Apache2::PodBrowser's handler. Use this mode if your POD files are installed in one directory tree which is accessible through the WEB server. You'll perhaps need an additional directory index handler.

Perldoc Mode

In perldoc mode you specify a Location where the handler resides. If you append a module name to the location URL as in

  http://localhost/location/Apache2::PodBrowser

you'll get its documentation.

Further, in perldoc mode you can ask for documentation for a given perl function similar to perldoc -f open at the command line. Simply call the location and give the wanted function as CGI keyword:

  http://localhost/location/?open

The same works also for special variables. Try

  http://localhost/location/?$_

and you'll see the documentation for $_.

Usually you want to use perldoc mode. It allows you to access PODs at their natural locations. On the downside, it is of course a bit slower.

Indexes

Also in perldoc mode, there are 2 indexes available, one of all installed modules and scripts that come with POD and one of built-in functions and variables.

The the handler location itself shows the module index:

  http://localhost/location/

If a single question mark ? is given as CGI keyword the function and variable index is shown:

  http://localhost/location/??

Don't worry you don't have to remember all these URLs. The pages are properly linked together.

CONFIGURATION

Direct Mode

Direct mode's basic configuration look like this:

  <Directory /...>
      Options +Indexes
      <Files ~ "\.p(od|m|l)">
          SetHandler modperl
          PerlResponseHandler Apache2::PodBrowser
          PerlSetVar  STYLESHEET /path/to/style.css
          PerlSetVar  PARSER Apache2::PodBrowser::DirectMode
      </Files>
  </Directory>

All *.pod, *.pm and *.pl files will magically be converted to HTML.

Perldoc Mode

For perldoc mode add the following lines to your httpd.conf:

  <Location /perldoc>
      SetHandler  modperl
      PerlHandler Apache2::PodBrowser
      PerlFixupHandler Apache2::PodBrowser::Fixup
      PerlSetVar  STYLESHEET fancy
  </Location>

You can then get documentation for module Apache2::PodBrowser at http://localhost/perldoc/Apache2::PodBrowser.

Finally, a particular Perl built-in function's or variable's documentation is at http://localhost/perldoc/?function_or_variable_name. For example http://localhost/perldoc/?open or http://localhost/perldoc/?$_.

At http://localhost/perldoc/ you'll see a module index and at http://localhost/perldoc/?? an index over all built-in functions and variables.

Configuration Variables

The following variables affect the work of Apache2::PodBrowser. They are all set by PerlSetVar or PerlAddVar. See t/conf/extra.conf.in for example configurations.

STYLESHEET

Specifies the stylesheet to use with the output HTML file.

  PerlSetVar  STYLESHEET /path/to/style.css

There are 2 stylesheets auto and fancy that come with this module. They are installed alongside in @INC. To use them either teach your Apache to look for them or use the provided fixup handler:

  PerlFixupHandler Apache2::PodBrowser::Fixup
  PerlSetVar STYLESHEET fancy    # or auto

If you want to use your own stylesheet simply specify its URL.

To use one of the built in styles in direct mode you have to teach apache where it is located. One way is to use an Alias and make the file accessible. Another is to use the provided fixup handler. For example

  <Directory /some/directory>
      Options +Indexes
      <Files ~ "\.p(od|m)">
          SetHandler modperl
          PerlResponseHandler Apache2::PodBrowser
          PerlSetVar STYLESHEET /auto.css
          PerlSetVar PARSER Apache2::PodBrowser::DirectMode
      </Files>
      <Files *.css>
          PerlFixupHandler Apache2::PodBrowser::Fixup
      </Files>
  </Directory>

In direct mode the stylesheet must be given as a complete URL not just auto or fancy.

INDEX

When INDEX is true, a table of contents is added at the top of the HTML document.

  PerlSetVar INDEX 1

By default, this is off.

The fancy stylesheet places the index into a sort of drop-down menu that is placed fixed at the right top corner of the page. So, it is always at hand if you want to jump to another part of the document. This works in most browsers with the necessary CSS support. Notably, the Internet Explorer is not among them.

GZIP

When GZIP is true, the whole HTTP body is compressed. The browser must accept gzip, and Compress::Zlib must be available. Otherwise, GZIP is ignored.

An appropriate Vary header is issued to make proxy servers happy.

Also the environment variables no-gzip and gzip-only-text/html that can be set for example by the BrowserMatch directive are regarded. See the mod_deflate documentation for more information

  PerlSetVar GZIP 1

By default, this is off.

PODDIR

This variable is useful only in perldoc mode.

It declares additional directories to look for PODs. This can be given multiple times. Directories given this way are searched before @INC.

  PerlAddVar PODDIR /path/to/project1
  PerlAddVar PODDIR /path/to/project2

NOINC

In perldoc mode POD files are normally looked up in @INC plus in the directories given by PODDIR. If NOINC is set then the @INC search is skipped. That means only the directories specifed in httpd.conf are scanned:

  PerlAddVar NOINC 1

For documentation requests for perl functions via http://localhost/perldoc/?functionname @INC is used nevertheless to locate perlfunc.pod if it is not found in one of the given directories.

In direct mode this variable is ignored.

CACHE

When in perldoc mode Apache2::PodBrowser uses Pod::Find::pod_find to generate a list of available POD files. This may take quite a while depending upon the number of directories and files to scan for POD.

To avoid to repeat this for each POD index request one can set up a cache.

  PerlSetVar CACHE /path/to/cache.mmdb

The cache file itself is created on the first access to the index. The POD index page then contains a link to update the cache. So, if a POD file is added or removed from the system this link is to be clicked to keep the POD index page up to date.

The cache file itself is a MMapDB object. If this module is not available you'll probably get a 404 - NOT FOUND response the next time the POD index page is requested if CACHE is set.

The directory containing the cache file must be writable by the httpd.

CONTENTTYPE

You'll probably need that only for plain text output with the Pod::Simple::Text parser. Here one can set the content type of the output.

  PerlSetVar CONTENTTYPE "text/plain; charset=UTF-8"

PARSER and LINKBASE

PARSER sets the POD-to-HTML converter class that is used. It should support at least the interface that Pod::Simple::Text provides.

The Pod::Simple::Text parser gives you plain text.

If Pod::Simple::HTML is used as parser one gets almost usable output except for the missing DOCTYPE HTML header and the broken linkage to other modules.

The default PARSER is Apache2::PodBrowser::Formatter and is suitable for perldoc mode. It derives from Pod::Simple::HTML but overrides the constructor new to provide a DOCTYPE and resolve_pod_page_link to fix the linkage.

If LINKBASE is not set or empty resolve_pod_page_link creates relative links to other modules of the type:

  ./Other::Module

If LINKBASE is set it is prepended before Other::Module instead of ./. For example you could set

  PerlSetVar LINKBASE http://search.cpan.org/perldoc?

to generate links to CPAN.

For perldoc mode an empty LINKBASE is best choice.

In direct mode an other parser Apache2::PodBrowser::DirectMode should be used. It derives from Apache2::PodBrowser::Formatter but overrides resolve_pod_page_link.

This time the link generator searches for the link destination POD by the module name with one of the following extensions appended: .pod, .pm and .pl. If none is found it resorts to its base class. And now LINKBASE makes sense.

If you know of a Apache2::PodBrowser running in perldoc mode you can point LINKBASE to that address. This way modules that does not exist in the local tree would be looked up there or on CPAN if LINKBASE points there.

If all that is unsuitable for you you can implement your own PARSER class. Have a look at the source code of this module. It is quite straight forward regarding the 2 parser classes.

The Fixup Handler

If you use your own stylesheet or teach apache to find one of the provided styles in the file system you don't need the fixup handler.

It simply does the file lookup for you.

If you don't like it just find the style sheet in your file system:

  find $(perl -e 'print "@INC"') -type f -name fancy.css

copy it into your DocumentRoot and set STYLESHEET to find it.

WHISHLIST

  • speed up POD index generation

HISTORY

As you may know there is already Apache2::Pod::HTML. This module has borrowed some ideas from it but is implemented anew. In fact, I had started by editing Apache2::Pod::HTML 0.27 but at a certain moment I had patched it into something that only vaguely remembered the original code. When the HTML functionality was ready I discovered that Apache2::Pod::Text had also to be taken care of. That was too much to bear.

Differences from Apache2::Pod::HTML as of version 0.01

  • POD index

    an index of all PODs found in the given scan directories is returned if the handler is called in perldoc mode without a module argument.

  • NOINC variable

  • PODDIR variable

  • PARSER variable

  • CONTENTTYPE variable

    new configuration variables

  • proper HTTP protocol handling

    Apache2::Pod::HTML does not issue a Vary HTTP header in GZIP mode. It does not support turning off GZIP for certain browsers by BrowserMatch. And it does not sent Content-Length, Last-Modified or ETag headers.

    Apache2::PodBrowser issues correct headers when GZIP is on. It also sends ETag, Last-Modified and Content-Length headers. And it checks if a conditional GET request meets its conditions and answers with HTTP code 304 (NOT MODIFIED) if so.

  • using CGI keywords instead of PATH_INFO

    how to pass function names to the handler in perldoc -f mode

  • proper HTTP error codes

    Apache2::Pod::HTML returns HTTP code 200 even if there is no POD found by a given name

  • CSS: fancy stylesheet

    Apache2::PodBrowser comes with 2 stylesheets, see above

  • CSS: sent by default handler

    Apache2::PodBrowser uses a fixup handler to reconfigure apache to ship included stylesheets by it's default response handler.

  • much better test suite

    Apache2::PodBrowser uses the Apache::Test framework to test its work. Apache2::Pod::HTML tests almost only the presence of POD.

Embedding HTML in POD

Picture of Torsten Foertsch

POD provides the

 =begin html
 ...
 =end html

or

 =for html ...

syntax. This module supports it. If you look at this document via this module you'll probably see a picture of me on the right side.

Example:

 =begin html

 <img align="right"
      alt="Picture of ..."
      src="http://host.name/image.jpg"
      border="0">

 =end html

You might notice that the image URL is absolute. Wouldn't it be good to bundle the images with the module, install them somewhere beside it in @INC and reference them relatively?

It is possible to do that in perldoc mode. Just strip off the .pm or .pod suffix from the installed perl module file name and make a directory with that name. For example assuming that this module is installed as:

 /perl/lib/Apache2/PodBrowser.pm

create the directory

 /perl/lib/Apache2/PodBrowser

and place the images there.

To include them in POD write:

 =begin html

 <img align="right"
      alt="Picture of ..."
      src="./Apache2::PodBrowser/torsten-foertsch.jpg"
      border="0">

 =end html

If the POD file name doesn't contain a dot (.) the last path component is stripped off to get the directory name.

Note that you need to write the package name again. You also need to either escape the semicolons as in src="Apache2%3A%3APodBrowser/torsten-foertsch.jpg" or put a ./ in front of the link.

A note about the content type of linked documents. Apache::PodBrowser does not enter a new request cycle to ship these documents. So, the normal Apache Content-Type guessing does not take place. Apache::PodBrowser knows a few file name extensions (png, jpg, jpeg, gif, js, pdf and html). For those it sends the correct Content-Type headers. All other documents are shipped as application/octet-stream.

If a document needs a different Content-Type header it can be passed as CGI parameter:

 src="Apache2%3A%3APodBrowser/torsten-foertsch.jpg?ct=text/plain"

The link above will ship the image as text/plain.

SEE ALSO

Apache2::Pod::HTML
Pod::Simple
Pod::Simple::HTML
Pod::Simple::Text

AUTHOR

Torsten Förtsch <torsten.foertsch@gmx.net>

LICENSE

This package is licensed under the same terms as Perl itself.