Writing webapps with Perl Dancer

Dancer A micro framework for writing web applications Alexis Sukrieh OSDCfr 2009

Alexis Sukrieh http://sukria.net http://twitter.com/sukria http://search.cpan.org/~sukria/

Dancer http://dancer.sukria.net $ sudo cpan Dancer http://github.com/sukria/Dancer

Description Syntax Application Tree Environments Deployment

Web Development in Perl can be :

Catalyst : it's huge, but, it's huge.

Plenty of other frameworks alike

Ruby introduced something else

A new approach to webapp development

package MyApp ; use Dancer; get '/' => sub { 'Hello OSDCfr 2009!' }; dance;

A dancer script is a webserver

$ ./myApp.pl >> Listening on 127.0.0.1:3000 == Entering the development dance floor ...

Working webapp ready to be hacked

» happiness : he can WSFC now

A Dancer app is defined with route handlers

a route handler is basically a sub

bound to an HTTP method (typically ' get ' or ' post ')

/foo /bar/:var /baz/* r('/stuff/([a-z0-9]+)/')

Static pattern (path) / /foo /bar/baz

pattern with named tokens /hello/:buddy my $name = params->{buddy}

pattern with anonymous tokens /show/*.* my ($file, $ext) = splat;

pseudo-regexp-defined patterns r('/post/([a-z0-9]+)') my ($post) = splat; # $1

processing a request = finding a matching route handler

404 No matching route handler » no joy

When found, a route handler is executed

it can alter the response headers get '/' => sub { content_type 'text/plain'; return 'this is plain text' };

pass to the next matching handler get '/lazy' => sub { pass and return false; };

serve a static file get '/dowload/:file' => sub { my $file = params->{file}; if (! -f $file) { pass and return false; } send_file $file; };

throw an error get '/forbidden' => sub { send_error 'Nope'; };

redirect to somewhere else get '/forbidden' => sub { redirect '/better/place' };

and of course, render a content get '/showme' => sub { template 'showme', { var => 'foo'}; };

return value = content to render

get '/' => sub { # ... debug 'here it is'; }; » logs/development.log

before sub { do_some_init_stuff(); params->{foo} = 'beenthere'; };

existing file in $appdir/public = file served , no handler needed

app.pl views/ index.tt layouts/ main.tt

app.pl views/ index.tt layouts/ main.tt config.yml

app.pl views/ index.tt layouts/ main.tt config.yml environments/ development.yml production.yml

app.pl views/ index.tt layouts/ main.tt config.yml environments/ development.yml production.yml public/

+ MyApp + MyApp/views + MyApp/views/index.tt + MyApp/views/layouts + MyApp/views/layouts/main.tt + MyApp/environments + MyApp/environments/development.yml + MyApp/environments/production.yml + MyApp/config.yml + MyApp/app.psgi + MyApp/MyApp.pm + MyApp/MyApp.pl + MyApp/public + MyApp/public/css + MyApp/public/css/style.css + MyApp/public/css/error.css + MyApp/public/images + MyApp/public/404.html + MyApp/public/500.html

» Working webapp, pre-configured, pre-designed and waiting for your hacks

settings : customizing the app

use Dancer; set layout => 'application' set foo => 42; set content_type =>'text/plain';

# config.yml layout: 'application' foo: 42 content_type: 'text/plain'

config.yml = global configuration

environments/foo.yml « foo » configuration

$ dancer -e foo runs the app in « foo » environment

development.yml warnings: 1 show_errors: 1 ...

production.yml warnings: 0 show_errors: 0 ...

For production needs, use PSGI/Plack

Plack is to Perl : what Rack is to Ruby what WSGI is to Python

universal server <-> application gateway

PSGI/Plack miyagawa http://plackperl.org

Dancer supports Plack since 0.9904

app.psgi tells Plack how to dance

use CGI::PSGI; use MyApp; my $handler = sub { my $env = shift; my $cgi = CGI::PSGI->new($env); Dancer->dance($cgi); };

The app is now PSGI/Plack aware

Apache (mod_psgi) nginx Perlbal HTTP::Server::Fast Plack (standalone)

Conf example with Apache <Location /> SetHandler perl-script PerlHandler Plack::Server::Apache2 PerlSetVar psgi_app /path/app.psgi </Location>

enjoy web development with Perl

Writing webapps with Perl Dancer

More Related Content

What's hot (20)

Similar to Writing webapps with Perl Dancer (20)

Recently uploaded (20)

Writing webapps with Perl Dancer