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TUWF-0.2
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/ TUWF

NAME

TUWF - The Ultimate Website Framework

DESCRIPTION

TUWF is a small framework designed for writing websites. It provides an abstraction layer to various environment-specific tasks and has common functions to ease the creation of both small and large websites.

Main features and limitations

TUWF may be The Ultimate Website Framework, but it is not the perfect solution to every problem. This section introduces you to some main features and limitations you will want to know about before using TUWF.

TUWF is small.

I have seen many frameworks being advertised as "small" or "minimal", yet they either require loads of dependencies or are not small at all. TUWF, on the other hand, is quite small. Its total codebase is significantly smaller than the primary code of CGI.pm, and TUWF requires absolutely no extra dependencies to run.

Some optional features, however, do require extra modules. In order to run TUWF in a FastCGI environment, the FCGI module is required. The TUWF::DB methods require DBI, and PerlIO::gzip is required when you want to enable content encoding.

The generated response is buffered.

This allows you to change the response completely while generating an other one, which is extremely useful if your code decides to throw an error while a part of the response has already been generated. In such a case your visitor will properly see your error page and not some messed up page that does not make sense. Thanks to this buffering, you will also be able to set cookies and send other headers after generating the contents of the page. And as an added bonus, your pages will be compressed more efficiently when output compression is enabled.

On the other hand, this means that you can't use TUWF for applications that require streaming dynamic content (e.g. a chat application), and you may get into memory issues when sending large files.

Everything is UTF-8.

All TUWF functions (with some exceptions) will only accept and return Unicode strings in Perls native encoding. All incoming data is assumed to be encoded in UTF-8 and all outgoing data will be encoded in UTF-8. This is generally what you want when developing new applications. If, for some very strange reason, you want all I/O with the browser to be in anything other than UTF-8, you won't be able to use TUWF. It is possible to use external resources which use other encodings, but you will have to decode() that into Perls native encoding before passing it to any TUWF function.

Designed for CGI and FastCGI environments.

TUWF is designed to be run in CGI and FastCGI environments, and has been optimized for FastCGI. That is, all modules will be pre-loaded at initialization.

Due to the singleton design of TUWF, you should avoid running TUWF websites in persistent environments that allow multiple websites to share the same process, such as mod_perl.

One (sub)domain is one website.

TUWF assumes that the website you are working on resides directly under a (sub)domain. That is, the homepage of your website has a URI like http://example.com/, and all sub-pages are directly beneath it. (e.g. http://example.com/about would be your "about" page).

While it is possible to run a TUWF website in a subdirectory (i.e. the homepage of the site would be http://example.com/mysite/), you will have to prefix all HTML links and registered URIs with the name of the subdirectory. This is neither productive, nor will it be fun when you wish to rename that directory later on.

One website is one (sub)domain.

In the same way as the previous point, TUWF is not made to handle websites that span multiple (sub)domains and have different behaviour for each one. It is possible - quite simple, even - to have a different subdomain affect some configuration parameter while keeping the structure and behaviour of the website the same as for the other domains. An example of this could be a language setting embedded in a subdomain: en.example.com could show to the English version of your site, while de.example.com will have the German translation.

Things will become messy as soon as you want (sub)domains to behave differently. If you want forum.example.com to host a forum and wiki.example.com to be a wiki, you will want to avoid programming both subdomains in the same TUWF script. A common solution is to write a separate script for each subdomain. It is still possible to share code among both sites by means of modules.

Backward compatibility is not guaranteed.

TUWF is the result of years of evolution, from one implementation to another and from one design to another. The reason TUWF has become what it is now is because of this unconstrained evolution. Providing backward compatibility in many cases complicates the implementation of new ideas and may add unwanted bloat to the framework. For this reason, future versions of TUWF may work differently from older versions, and may not be backward compatible with code written for an older version.

When using TUWF for your project, it is adviced to get one version of TUWF and stick to that, until you have time to check out a later version and update your code to work with that one.

General structure of a TUWF website

A website written using TUWF consists of a single Perl script, optionally accompanied by several modules. The script is responsible for loading, initializing and running TUWF, and can be used as a CGI or FastCGI script. For small and simple websites, this script may contain the code for the entire website. Usually, however, the actual implementation of the website is spread among the various modules.

The script can load the modules by calling TUWF::load() or TUWF::load_recursive(). TUWF configuration variables can be set using TUWF::set(), and URIs can be mapped to functions using TUWF::register(). These functions can also be called by the loaded modules. In fact, for larger websites it is common for the script to only initialize TUWF and load the modules, while all calls to TUWF::register() are done from the modules.

The framework is based on callbacks: At initialization, your code registers callbacks to the framework and then passes the control to TUWF using TUWF::run(). TUWF will then handle requests and call the appropriate functions you registered.

The TUWF Object

While TUWF can not really be called object oriented, it does use one major object, called the TUWF object. This object can be accessed from $TUWF::OBJ and is passed as the first argument to all callback functions. Even though it is an "instance" of TUWF::Object, you are encouraged to use it as if it is the main object for your website: You can use it to store global configuration settings and other shared data.

All modules loaded using TUWF::load() and its recursive counterpart can export functions; These functions are automatically imported in the TUWF::Object namespace and can be used as methods of the TUWF object. This allows for an easy method to split the functionality of your website among different functions and files, without having to constantly load and import your utility modules in each file that uses them.

Of course, with all exported functions being imported into a single namespace, this does call for some function naming conventions to avoid name conflicts and other confusing issues. The main TUWF methods use camelCase and are often prefixed with a short identifier to indicate to which module or section they belong. For example, the TUWF::Request methods all start with req and TUWF::Response with res. It is a good idea to adopt this style when you write your own methods.

Be warned that the data in the TUWF object may or may not persist among multiple requests, depending on whether your script is running in FastCGI or CGI mode, respectively. In particular, it is a bad idea to store session data in this object, assuming it to be available on the next request. Storing data specific to a single request in the object is fine, as long as you make sure to reset or re-initialize the data at the beginning of the request. The pre_request_handler is useful for such practice.

Utility functions

Besides the above mentioned methods, TUWF also provides various handy functions. These functions are implemented in the TUWF submodules (e.g. TUWF::Misc) and can be imported manually through these modules. Check out the SEE ALSO below for the list of submodules.

An alternative, and more convenient, approach to importing these functions into your code is also available: you can import functions from multiple submodules at once by adding their names and/or tags to the use TUWF; line.

The following two examples are equivalent:

  # the simple approach
  use TUWF ':xml', 'uri_escape', 'sqlprint';

  # the classic approach
  use TUWF;
  use TUWF::XML ':xml';
  use TUWF::Misc 'uri_escape';
  use TUWF::DB 'sqlprint';

The first use TUWF; line of the classic approach is not required if all you need is to import the functions. Omitting this line from your main website script, however, will cause the main TUWF code to not be loaded into memory, and the global functions (listed below) will then not be available. The simple approach does not suffer from this problem and is therefore recommended.

GLOBAL FUNCTIONS

The main TUWF namespace contains several functions used to initialize the framework and register the callbacks for your website.

TUWF::load(@modules)

Loads the listed module names and imports their exported functions to the TUWF::Object namespace. The modules must be available in any subdirectory in @INC.

  # make sure the website modules are available from @INC
  use lib 'mylib';
  
  # load mylib/MyWebsite/HomePage.pm
  TUWF::load('MyWebsite::HomePage');
  
  # load two other modules
  TUWF::load('MyWebsite::Forum', 'MyUtilities');

Note that your modules must be proper Perl modules. That is, they should return a true value (usually done by adding 1; to the end of the file) and they should have the correct namespace definition.

TUWF::load_recursive(@modules)

Works the same as TUWF::load(), but this also loads all submodules.

  # the following will load MyWebsite.pm (if it exists) and all modules below
  # the MyWebsite/ directory (if any).
  TUWF::load_recursive('MyWebsite');

Note that all submodules must be in the same parent directory in @INC.

TUWF::register(regex => subroutine, ..)

Maps a URI to a function. The regex is matched to reqPath() and must match the path from the begin to the end. (That is, the regex is used between ^ and $ marks). Since reqPath() does not contain a leading / character, these should also be omitted in the regexes. It is common to use the qr{} operator to quote the regex, which prevents you from having to escape slashes in the path as would be required with qr//.

All registered regexes are matched against any incoming URI, and the subroutine corresponding to the first matched regex will be called to handle the request. The first argument to the subroutine will be the main TUWF object. If the regular expression has capture buffers, these will also be provided as additional arguments.

  TUWF::register(
    # empty regex = root URI (/)
    # myhomepage() will be called with the main TUWF object
    qr{}  => \&myhomepage,
  
    # The following will match on any /user/<numeric-id> URI.
    # userpage() will be called with
    # - the TUWF object and
    # - the id-part of the URI ($1 in the regular expression)
    qr{user/(\d+)} => \&userpage,
  );

TUWF::set(key => value, ..)

Get or set TUWF configuration variables. When called with only one argument, will return the configuration variable with that key. Otherwise the number of arguments must be a multiple of 2, setting the configuration parameters.

content_encoding

Set the default output encoding. Supported values are none, gzip, deflate, auto. See TUWF::Response for more information. Default: auto.

When set to a hashref, will be used as the default options to resCookie(). These options can still be overruled by each individual call to resCookie(). This can be useful when globally setting the cookie domain:

  $self->set(cookie_defaults => { domain => '.example.org' });
  $self->resCookie(foo => 'bar');
  
  # is equivalent to:
  $self->resCookie(foo => 'bar', domain => '.example.org');
  # for each call to resCookie()

Default: undef (disabled).

When set to a non-empty string, its value will be used as prefix to all cookie names used by reqCookie() and resCookie(). reqCookie() will act as if all cookies not having the configured prefix never existed, and removes the prefix when used in list context. resCookie() will simply add the prefix to all outgoing cookies. Default: undef (disabled).

db_login

Sets the login information for the TUWF::DB functions. Can be set to either an arrayref or a subroutine reference.

In the case of an arrayref, the array should have three elements, containing the first three arguments to DBI::connect(). Do not include the last options argument, TUWF will set the appropriate options itself. When necessary, however, it is still possible to set options using the DSN string itself, see the DBI documentation for more information. TUWF::DB will automatically enable the unicode/utf8 flag for DBD::mysql, DBD::Pg and DBD::SQLite.

When setting this to a subroutine reference, the subroutine will be called when connecting to the database, with the main TUWF object as only argument. The subroutine is expected to return a DBI instance. It is the responsibility of the subroutine to set the correct DBI options. In particular, it is important to have RaiseError enabled and AutoCommit disabled. It is also recommended to enable unicode support if your database driver has such an option.

Default: undef (disabled).

debug

Set to a true value to enable debug mode. When debug mode is enabled and logfile is specified, TUWF will log page generation times for each request. This flag can be easily read through the debug() method, so you can also use is in your own code. Default: 0 (disabled).

error_400_handler

Similar to error_404_handler, but is called when something in the request data did not make sense to TUWF. In the current implementation, this only happens when the request data contains non-UTF8-encoded text. A warning is written to the log file when this happens.

error_404_handler

Set this to a subroutine reference if you want to write your own 404 error page. The subroutine will be called with TUWF object as only argument, and is expected to generate a response.

error_405_handler

Similar to error_404_handler, but is called when the HTTP request method is something other than HEAD, GET or POST. These requests are usually generated by bots or applications which don't actually read the response contents, so overriding the default 405 error page makes little sense in most situations. If you do override it, do not forget to add an Allow HTTP header to the response, as required by the HTTP standard.

error_413_handler

Similar to error_404_handler, but is called when the POST body exceeds the configured max_post_body.

error_500_handler

Set this to a subroutine reference if you want to write your own 500 error page. The subroutine will be called with the TUWF object as first argument and the error message as second argument. When logfile is set, a detailed error report will be written to the log. It is recommended to ignore the error message passed to your subroutine and to enable the log file, so you won't risk sending sensitive information to your visitors.

logfile

To enable logging, set this to a string that indicates the path to your log file. The file must of course be writable by your script. TUWF automatically logs all Perl warnings, and when one of your callbacks throws an exception a full request dump with useful information will be logged, allowing you to easily locate and fix the problem. You can also write information to the log yourself using the log() method. Default: undef (disabled).

log_format

Set to a subroutine reference to influence the default log format. The subroutine is passed three arguments: the main TUWF object, the URI of the current request (or '[init]' if log() was called outside of a request), and the log message. The subroutine should return the string to be written to the log, including trailing newline.

Be warned that your subroutine can be called even when no request is being processed or before some resources have been initialized, so you should avoid using such resources. In paticular, do not call any database functions from this subroutine, as the database connection may not be in a defined state. Any Perl warnings generated by this subroutine will not be logged in order to avoid infinite recursion.

log_slow_pages

Setting this to a number will log all pages that took longer to generate than the time indicated in the number, in milliseconds. The format of the log line is the same as used when the debug option is enabled. This option is ignored when debug is enabled, since in that case all pages will be logged anyway. Default: 0 (disabled).

log_queries

Setting this to a true value will write all database queries to the log file. Useful when debugging queries, but can generate a lot of data. Default: 0 (disabled).

mail_from

The default value of the From: header of mail sent using mail(). Default: <noreply-yawf@blicky.net>.

mail_sendmail

The path to the sendmail command, used by mail(). Default: /usr/sbin/sendmail.

max_post_body

Maximum length of the contents of POST requests, in bytes. This disallows people to upload large files and potentially cause your script to run out of memory. Set to 0 to disable this limit. Default: 10MB.

pre_request_handler

Set to a subroutine reference if you want to perform some actions before TUWF calls your URI handling function. The subroutine must return a true value to indicate that TUWF can continue processing the request as usual. If the subroutine returns false, TUWF will assume the subroutine has generated a response and will halt any further processing. This callback is often used for initializing or resetting request-specific data, and parsing cookies or other request data to set preferences or session information.

post_request_handler

Similar to post_request_handler, except it will be called after the request has been processed but before it has been sent to the client. This callback will not be called if any of the functions before threw an exception.

validate_templates

Hashref, templates for the kv_validate() function when called using formValidate(). The recommended way to add new templates is to call TUWF::set() with a single argument:

  TUWF::set('validate_templates')->{$key} = \%validate_options;
xml_pretty

Passed to the pretty option of TUWF::XML->new(). See TUWF::XML. Default: 0 (disabled).

TUWF::run()

After TUWF has been initialized, all modules have been loaded and all URIs have been registered, the last thing that remains is to execute TUWF::run(). This function will start processing requests and calls the appropriate callbacks at the appropriate stages.

Whether this function ever returns or not depends on the environment your script is running in; if you're running your script in a CGI environment, TUWF::run() will return as soon as the request has been processed. If, on the other hand, you are running the script as a FastCGI script, it will keep waiting for new incoming requests and will therefore never return. It is a bad idea to assume either way, so you want to avoid putting any run-time code after calling TUWF::run().

BASIC METHODS

This section documents the basic TUWF object methods provided by TUWF.pm. The TUWF object provides many other methods as well, which are implemented and documented in the various sub-modules. See the documentation of each sub-module for the methods it provides.

debug()

Returns the value of the debug setting.

log(message)

Writes a message to the log file configured with logfile. When no log file is configured, log() will do nothing. The message argument may contain newlines, which will be nicely (re-)formatted before logging, in order to avoid ambiguity with other log entries. By default the log message will be prefixed with the date and URI of the request, but this can be changed with the log_format setting.

This function is not used very often in practice, since it is easier to simply use Perl's warn() function instead. TUWF automatically writes all warnings to the log file.

SERVER CONFIGURATION

Since a website written using TUWF consists of a single Perl script that acts as the main script for your site, the only thing you have to do is tell your webserver to run it. There are generally two things you should take care of:

  1. You can run the script as CGI or FastCGI script. In the case of FastCGI, you will need the FCGI module.

  2. You have to make sure all requests to non-existing files are passed to your script, in order for the URI rewriting in TUWF to work.

The following examples show how to configure your server to run the examples/singlefile.pl script from the TUWF distribution. I assume the TUWF distribution is unpacked in /tuwf and the site runs on the hostname test.example.com.

Examples for Apache (2.2)

CGI mode:

  <VirtualHost *:*>
    ServerName test.example.com
    DocumentRoot /tuwf/examples
    AddHandler cgi-script .pl

    # %{REQUEST_FILENAME} does not seem to always work inside a <VirtualHost>
    # But it should be equivalent to "%{DOCUMENT_ROOT}/%{REQUEST_URI}"
    RewriteEngine On
    RewriteCond "%{DOCUMENT_ROOT}/%{REQUEST_URI}" !-s
    RewriteRule ^/ /singlefile.pl
  </VirtualHost>

It is possible to move the mod_rewrite statements into a .htaccess file, in which case you can remove the Rewrite* lines in the above example and put the following in your .htaccess file:

  RewriteEngine On
  RewriteCond %{REQUEST_FILENAME} !-s
  RewriteRule ^/ /singlefile.pl

FastCGI mode, using mod_fcgid. With this configuration it is possible to have the documentroot point to a different directory than where the TUWF script resides, which could improve security.

  <VirtualHost *:*>
    ServerName test.example.com
    DocumentRoot /whatever/you/want
    AddHandler fcgid-script .pl
    FcgidWrapper /tuwf/examples/singlefile.pl virtual

    # same as above example, except 'singlefile.pl' can be anything,
    # as long as it ends with '.pl'
    RewriteEngine On
    RewriteCond "%{DOCUMENT_ROOT}/%{REQUEST_URI}" !-s
    RewriteRule ^/ /singlefile.pl
  </VirtualHost>

Again, it is possible to move the rewrites into a .htaccess. All of the above examples assume the referenced directories have the appropriate options set using a <Directory> clause.

Examples for lighttpd (1.4)

CGI mode:

  $HTTP["host"] == "test.example.com" {
    server.document-root = "/tuwf/examples"
    cgi.assign = ( ".cgi" => "" )
    server.error-handler-404 = "/singlefile.pl"
  }

FastCGI:

  fastcgi.server = (
    ".singlefile" => ((
      "socket"            => "/tmp/perl-tuwf-singlefile.socket",
      "bin-path"          => "/tuwf/examples/singlefile.pl",
      "check-local"       => "disable"
    ))
  )

  $HTTP["host"] == "test.example.com" {
    server.document-root = "/whatever/you/want"
    cgi.assign = ( ".cgi" => "" )
    server.error-handler-404 = "/something.singlefile"
  }

SEE ALSO

TUWF::DB, TUWF::Misc, TUWF::Request, TUWF::Response, TUWF::XML.

The homepage of TUWF can be found at http://dev.yorhel.nl/tuwf.

TUWF is available on a git repository at http://g.blicky.net/tuwf.git/.

COPYRIGHT

Copyright (c) 2008-2011 Yoran Heling.

This module is part of the TUWF framework and is free software available under the liberal MIT license. See the COPYING file in the TUWF distribution for the details.

AUTHOR

Yoran Heling <projects@yorhel.nl>