sub foo {
my $result = blocking_subroutine();
...
}
A non-blocking operation on the other hand lets the calling subroutine continue execution even though the subroutine is not yet finished. Instead of waiting, the calling subroutine passes along a callback to be executed once the subroutine is finished, this is called continuation-passing style.
sub foo {
non_blocking_subroutine(sub {
my $result = shift;
...
});
...
}
While Mojolicious has been designed from the ground up for non-blocking I/O and event loops, it is not possible to magically make Perl code non-blocking. You have to use specialized non-blocking code available through modules like Mojo::IOLoop and Mojo::UserAgent, or third-party event loops. You can wrap your blocking code in subprocesses though to prevent it from interfering with your non-blocking code.
while (1) {
my @readable = test_fds_for_readability();
handle_readable_fds(@readable);
my @writable = test_fds_for_writability();
handle_writable_fds(@writable);
my @expired = test_timers();
handle_timers(@expired);
}
In Mojolicious this event loop is Mojo::IOLoop.
..........................................
: :
+--------+ : +-----------+ +---------------+ :
| |-------->| | | | :
| client | : | reverse |----->| Mojolicious | :
| |<--------| proxy | | application | :
+--------+ : | |<-----| | :
: +-----------+ +---------------+ :
: :
.. system boundary (e.g. same host) ......
This setup introduces some problems, though: the application will receive requests from the reverse proxy instead of the original client; the address/hostname where your application lives internally will be different from the one visible from the outside; and if terminating SSL, the reverse proxy exposes services via HTTPS while using HTTP towards the Mojolicious application.
As an example, compare a sample request from the client and what the Mojolicious application receives:
client reverse proxy Mojolicious app
__|__ _______________|______________ ____|____
/ \ / \ / \
1.2.3.4 --HTTPS--> api.example.com 10.20.30.39 --HTTP--> 10.20.30.40
GET /foo/1 HTTP/1.1 | GET /foo/1 HTTP/1.1
Host: api.example.com | Host: 10.20.30.40
User-Agent: Firefox | User-Agent: ShinyProxy/1.2
... | ...
However, now the client address is no longer available (which might be useful for analytics, or Geo-IP) and URLs generated via ``url_for'' in Mojolicious::Controller will look like this:
http://10.20.30.40/bar/2
instead of something meaningful for the client, like this:
https://api.example.com/bar/2
To solve these problems, you can configure your reverse proxy to send the missing data (see ``Nginx'' and ``Apache/mod_proxy'') and tell your application about it by setting the environment variable "MOJO_REVERSE_PROXY". For finer control, ``Rewriting'' includes examples of how the changes could be implemented manually.
$ ./script/my_app daemon Server available at http://127.0.0.1:3000
It is available to every application through the command Mojolicious::Command::daemon, which has many configuration options and is known to work on every platform Perl works on with its single-process architecture.
$ ./script/my_app daemon -h ...List of available options...
Another huge advantage is that it supports TLS and WebSockets out of the box, a development certificate for testing purposes is built right in, so it just works, but you can specify all listen locations supported by ``listen'' in Mojo::Server::Daemon.
$ ./script/my_app daemon -l https://[::]:3000 Server available at https://[::]:3000
To manage the web server with systemd, you can use a unit configuration file like this.
[Unit] Description=My Mojolicious application After=network.target [Service] Type=simple ExecStart=/home/sri/myapp/script/my_app daemon -m production -l http://*:8080 [Install] WantedBy=multi-user.target
$ ./script/my_app prefork Server available at http://127.0.0.1:3000
Since all built-in web servers are based on the Mojo::IOLoop event loop, they scale best with non-blocking operations. But if your application for some reason needs to perform many blocking operations, you can improve performance by increasing the number of worker processes and decreasing the number of concurrent connections each worker is allowed to handle (often as low as 1).
$ ./script/my_app prefork -m production -w 10 -c 1 Server available at http://127.0.0.1:3000
During startup your application is preloaded in the manager process, which does not run an event loop, so you can use ``next_tick'' in Mojo::IOLoop to run code whenever a new worker process has been forked and its event loop gets started.
use Mojolicious::Lite;
Mojo::IOLoop->next_tick(sub {
app->log->info("Worker $$ star...ALL GLORY TO THE HYPNOTOAD!");
});
get '/' => {text => 'Hello Wor...ALL GLORY TO THE HYPNOTOAD!'};
app->start;
And to manage the pre-forking web server with systemd, you can use a unit configuration file like this.
[Unit] Description=My Mojolicious application After=network.target [Service] Type=simple ExecStart=/home/sri/myapp/script/my_app prefork -m production -l http://*:8080 [Install] WantedBy=multi-user.target
Mojo::Server::Morbo +- Mojo::Server::Daemon
It is basically a restarter that forks a new Mojo::Server::Daemon web server whenever a file in your project changes, and should therefore only be used during development. To start applications with it you can use the morbo script.
$ morbo ./script/my_app Server available at http://127.0.0.1:3000
Mojo::Server::Hypnotoad |- Mojo::Server::Daemon [1] |- Mojo::Server::Daemon [2] |- Mojo::Server::Daemon [3] +- Mojo::Server::Daemon [4]
It is based on the Mojo::Server::Prefork web server, which adds pre-forking to Mojo::Server::Daemon, but optimized specifically for production environments out of the box. To start applications with it you can use the hypnotoad script, which listens on port 8080, automatically daemonizes the server process and defaults to "production" mode for Mojolicious and Mojolicious::Lite applications.
$ hypnotoad ./script/my_app
Many configuration settings can be tweaked right from within your application with ``config'' in Mojolicious, for a full list see ``SETTINGS'' in Mojo::Server::Hypnotoad.
use Mojolicious::Lite;
app->config(hypnotoad => {listen => ['http://*:80']});
get '/' => {text => 'Hello Wor...ALL GLORY TO THE HYPNOTOAD!'};
app->start;
Or just add a "hypnotoad" section to your Mojolicious::Plugin::Config or Mojolicious::Plugin::JSONConfig configuration file.
# myapp.conf
{
hypnotoad => {
listen => ['https://*:443?cert=/etc/server.crt&key=/etc/server.key'],
workers => 10
}
};
But one of its biggest advantages is the support for effortless zero downtime software upgrades (hot deployment). That means you can upgrade Mojolicious, Perl or even system libraries at runtime without ever stopping the server or losing a single incoming connection, just by running the command above again.
$ hypnotoad ./script/my_app Starting hot deployment for Hypnotoad server 31841.
You might also want to enable proxy support if you're using Hypnotoad behind a reverse proxy. This allows Mojolicious to automatically pick up the "X-Forwarded-For" and "X-Forwarded-Proto" headers.
# myapp.conf
{hypnotoad => {proxy => 1}};
To manage Hypnotoad with systemd, you can use a unit configuration file like this.
[Unit] Description=My Mojolicious application After=network.target [Service] Type=forking PIDFile=/home/sri/myapp/script/hypnotoad.pid ExecStart=/path/to/hypnotoad /home/sri/myapp/script/my_app ExecReload=/path/to/hypnotoad /home/sri/myapp/script/my_app KillMode=process [Install] WantedBy=multi-user.target
$ ./script/my_app prefork -P /tmp/first.pid -l http://*:8080?reuse=1 Server available at http://127.0.0.1:8080
All you have to do, is to start a second web server listening to the same port, and stop the first web server gracefully afterwards.
$ ./script/my_app prefork -P /tmp/second.pid -l http://*:8080?reuse=1 Server available at http://127.0.0.1:8080 $ kill -s TERM `cat /tmp/first.pid`
Just remember that both web servers need to be started with the "reuse" parameter.
upstream myapp {
server 127.0.0.1:8080;
}
server {
listen 80;
server_name localhost;
location / {
proxy_pass http://myapp;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
}
}
<VirtualHost *:80>
ServerName localhost
<Proxy *>
Require all granted
</Proxy>
ProxyRequests Off
ProxyPreserveHost On
ProxyPass /echo ws://localhost:8080/echo
ProxyPass / http://localhost:8080/ keepalive=On
ProxyPassReverse / http://localhost:8080/
RequestHeader set X-Forwarded-Proto "http"
</VirtualHost>
ScriptAlias / /home/sri/my_app/script/my_app/
$ plackup ./script/my_app
Plack provides many server and protocol adapters for you to choose from, such as "FCGI", "uWSGI" and "mod_perl".
$ plackup ./script/my_app -s FCGI -l /tmp/myapp.sock
The "MOJO_REVERSE_PROXY" environment variable can be used to enable proxy support, this allows Mojolicious to automatically pick up the "X-Forwarded-For" and "X-Forwarded-Proto" headers.
$ MOJO_REVERSE_PROXY=1 plackup ./script/my_app
If an older server adapter is unable to correctly detect the application home directory, you can simply use the "MOJO_HOME" environment variable.
$ MOJO_HOME=/home/sri/my_app plackup ./script/my_app
There is no need for a ".psgi" file, just point the server adapter at your application script, it will automatically act like one if it detects the presence of a "PLACK_ENV" environment variable.
#!/usr/bin/env plackup -s FCGI
use Plack::Builder;
builder {
enable 'Deflater';
require './script/my_app';
};
Mojo::Server::PSGI can be used directly to load and customize applications in the wrapper script.
#!/usr/bin/env plackup -s FCGI
use Mojo::Server::PSGI;
use Plack::Builder;
builder {
enable 'Deflater';
my $server = Mojo::Server::PSGI->new;
$server->load_app('./script/my_app');
$server->app->config(foo => 'bar');
$server->to_psgi_app;
};
But you could even use middleware right in your application.
use Mojolicious::Lite;
use Plack::Builder;
get '/welcome' => sub {
my $c = shift;
$c->render(text => 'Hello Mojo!');
};
builder {
enable 'Deflater';
app->start;
};
# Change scheme if "X-Forwarded-HTTPS" header is set
$app->hook(before_dispatch => sub {
my $c = shift;
$c->req->url->base->scheme('https')
if $c->req->headers->header('X-Forwarded-HTTPS');
});
Since reverse proxies generally don't pass along information about path prefixes your application might be deployed under, rewriting the base path of incoming requests is also quite common. This allows ``url_for'' in Mojolicious::Controller for example, to generate portable URLs based on the current environment.
# Move first part and slash from path to base path in production mode
$app->hook(before_dispatch => sub {
my $c = shift;
push @{$c->req->url->base->path->trailing_slash(1)},
shift @{$c->req->url->path->leading_slash(0)};
}) if $app->mode eq 'production';
Mojo::URL objects are very easy to manipulate, just make sure that the URL ("foo/bar?baz=yada"), which represents the routing destination, is always relative to the base URL ("http://example.com/myapp/"), which represents the deployment location of your application.
use Mojo::Server;
# Load application with mock server
my $server = Mojo::Server->new;
my $app = $server->load_app('./myapp.pl');
# Access fully initialized application
say for @{$app->static->paths};
say $app->config->{secret_identity};
say $app->dumper({just => 'a helper test'});
say $app->build_controller->render_to_string(template => 'foo');
The plugin Mojolicious::Plugin::Mount uses this functionality to allow you to combine multiple applications into one and deploy them together.
use Mojolicious::Lite;
app->config(hypnotoad => {listen => ['http://*:80']});
plugin Mount => {'test1.example.com' => '/home/sri/myapp1.pl'};
plugin Mount => {'test2.example.com' => '/home/sri/myapp2.pl'};
app->start;
use Mojolicious::Lite;
use Mojo::IOLoop;
use Mojo::Server::Daemon;
# Normal action
get '/' => {text => 'Hello World!'};
# Connect application with web server and start accepting connections
my $daemon
= Mojo::Server::Daemon->new(app => app, listen => ['http://*:8080']);
$daemon->start;
# Call "one_tick" repeatedly from the alien environment
Mojo::IOLoop->one_tick while 1;
use Mojolicious::Lite;
# Search MetaCPAN for "mojolicious"
get '/' => sub {
my $c = shift;
$c->ua->get('fastapi.metacpan.org/v1/module/_search?q=mojolicious' => sub {
my ($ua, $tx) = @_;
$c->render('metacpan', hits => $tx->result->json->{hits}{hits});
});
};
app->start;
__DATA__
@@ metacpan.html.ep
<!DOCTYPE html>
<html>
<head><title>MetaCPAN results for "mojolicious"</title></head>
<body>
% for my $hit (@$hits) {
<p><%= $hit->{_source}{release} %></p>
% }
</body>
</html>
The callback passed to ``get'' in Mojo::UserAgent will be executed once the request to the backend web service has been finished, this is called continuation-passing style.
use Mojolicious::Lite;
use Mojo::Promise;
use Mojo::URL;
# Search MetaCPAN for "mojo" and "minion"
get '/' => sub {
my $c = shift;
# Create two promises
my $url = Mojo::URL->new('fastapi.metacpan.org/v1/module/_search');
my $mojo = $c->ua->get_p($url->clone->query({q => 'mojo'}));
my $minion = $c->ua->get_p($url->clone->query({q => 'minion'}));
# Render a response once both promises have been resolved
Mojo::Promise->all($mojo, $minion)->then(sub {
my ($mojo, $minion) = @_;
$c->render(json => {
mojo => $mojo->[0]->result->json('/hits/hits/0/_source/release'),
minion => $minion->[0]->result->json('/hits/hits/0/_source/release')
});
})->catch(sub {
my $err = shift;
$c->reply->exception($err);
})->wait;
};
app->start;
To create promises manually you just wrap your continuation-passing style APIs in functions that return promises. Here's an example for how ``get_p'' in Mojo::UserAgent works internally.
use Mojo::UserAgent;
use Mojo::Promise;
# Wrap a user agent method with a promise
my $ua = Mojo::UserAgent->new;
sub get_p {
my $promise = Mojo::Promise->new;
$ua->get(@_ => sub {
my ($ua, $tx) = @_;
my $err = $tx->error;
$promise->resolve($tx) if !$err || $err->{code};
$promise->reject($err->{message});
});
return $promise;
}
# Use our new promise generating function
get_p('https://mojolicious.org')->then(sub {
my $tx = shift;
say $tx->result->dom->at('title')->text;
})->wait;
Promises have three states, they start out as "pending" and you call ``resolve'' in Mojo::Promise to transition them to "fulfilled", or ``reject'' in Mojo::Promise to transition them to "rejected".
use Mojolicious::Lite;
use Mojo::IOLoop;
# Wait 3 seconds before rendering a response
get '/' => sub {
my $c = shift;
Mojo::IOLoop->timer(3 => sub {
$c->render(text => 'Delayed by 3 seconds!');
});
};
app->start;
Recurring timers created with ``recurring'' in Mojo::IOLoop are slightly more powerful, but need to be stopped manually, or they would just keep getting emitted.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Count to 5 in 1 second steps
get '/' => sub {
my $c = shift;
# Start recurring timer
my $i = 1;
my $id = Mojo::IOLoop->recurring(1 => sub {
$c->write_chunk($i);
$c->finish if $i++ == 5;
});
# Stop recurring timer
$c->on(finish => sub { Mojo::IOLoop->remove($id) });
};
app->start;
Timers are not tied to a specific request or connection, and can even be created at startup time.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Check title in the background every 10 seconds
my $title = 'Got no title yet.';
Mojo::IOLoop->recurring(10 => sub {
app->ua->get('https://mojolicious.org' => sub {
my ($ua, $tx) = @_;
$title = $tx->result->dom->at('title')->text;
});
});
# Show current title
get '/' => sub {
my $c = shift;
$c->render(json => {title => $title});
};
app->start;
Just remember that all these non-blocking operations are processed cooperatively, so your callbacks shouldn't block for too long.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Operation that would block the event loop for 5 seconds
get '/' => sub {
my $c = shift;
Mojo::IOLoop->subprocess(
sub {
my $subprocess = shift;
sleep 5;
return '♥', 'Mojolicious';
},
sub {
my ($subprocess, $err, @results) = @_;
$c->reply->exception($err) and return if $err;
$c->render(text => "I $results[0] $results[1]!");
}
);
};
app->start;
The first callback will be executed in a child process, without blocking the event loop of the parent process. The results of the first callback will then be shared between both processes, and the second callback executed in the parent process.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Forward error messages to the application log
Mojo::IOLoop->singleton->reactor->on(error => sub {
my ($reactor, $err) = @_;
app->log->error($err);
});
# Exception only gets logged (and connection times out)
get '/connection_times_out' => sub {
my $c = shift;
Mojo::IOLoop->timer(2 => sub {
die 'This request will not be getting a response';
});
};
# Exception gets caught and handled
get '/catch_exception' => sub {
my $c = shift;
Mojo::IOLoop->timer(2 => sub {
eval { die 'This request will be getting a response' };
$c->reply->exception($@) if $@;
});
};
app->start;
A default subscriber that turns all errors into warnings will usually be added by Mojo::IOLoop as a fallback.
Mojo::IOLoop->singleton->reactor->unsubscribe('error');
During development or for applications where crashing is simply preferable, you can also make every exception that gets thrown in a callback fatal by removing all of its subscribers.
use Mojolicious::Lite;
# Template with browser-side code
get '/' => 'index';
# WebSocket echo service
websocket '/echo' => sub {
my $c = shift;
# Opened
$c->app->log->debug('WebSocket opened');
# Increase inactivity timeout for connection a bit
$c->inactivity_timeout(300);
# Incoming message
$c->on(message => sub {
my ($c, $msg) = @_;
$c->send("echo: $msg");
});
# Closed
$c->on(finish => sub {
my ($c, $code, $reason) = @_;
$c->app->log->debug("WebSocket closed with status $code");
});
};
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head><title>Echo</title></head>
<body>
<script>
var ws = new WebSocket('<%= url_for('echo')->to_abs %>');
// Incoming messages
ws.onmessage = function (event) {
document.body.innerHTML += event.data + '<br/>';
};
// Outgoing messages
ws.onopen = function (event) {
window.setInterval(function () { ws.send('Hello Mojo!') }, 1000);
};
</script>
</body>
</html>
The event ``finish'' in Mojo::Transaction::WebSocket will be emitted right after the WebSocket connection has been closed.
$c->tx->with_compression;
You can activate "permessage-deflate" compression with ``with_compression'' in Mojo::Transaction::WebSocket, this can result in much better performance, but also increases memory usage by up to 300KiB per connection.
my $proto = $c->tx->with_protocols('v2.proto', 'v1.proto');
You can also use ``with_protocols'' in Mojo::Transaction::WebSocket to negotiate a subprotocol.
use Mojolicious::Lite;
# Template with browser-side code
get '/' => 'index';
# EventSource for log messages
get '/events' => sub {
my $c = shift;
# Increase inactivity timeout for connection a bit
$c->inactivity_timeout(300);
# Change content type and finalize response headers
$c->res->headers->content_type('text/event-stream');
$c->write;
# Subscribe to "message" event and forward "log" events to browser
my $cb = $c->app->log->on(message => sub {
my ($log, $level, @lines) = @_;
$c->write("event:log\ndata: [$level] @lines\n\n");
});
# Unsubscribe from "message" event again once we are done
$c->on(finish => sub {
my $c = shift;
$c->app->log->unsubscribe(message => $cb);
});
};
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head><title>LiveLog</title></head>
<body>
<script>
var events = new EventSource('<%= url_for 'events' %>');
// Subscribe to "log" event
events.addEventListener('log', function (event) {
document.body.innerHTML += event.data + '<br/>';
}, false);
</script>
</body>
</html>
The event ``message'' in Mojo::Log will be emitted for every new log message and the event ``finish'' in Mojo::Transaction right after the transaction has been finished.
use Mojolicious::Lite;
use Scalar::Util 'weaken';
# Intercept multipart uploads and log each chunk received
hook after_build_tx => sub {
my $tx = shift;
# Subscribe to "upgrade" event to identify multipart uploads
weaken $tx;
$tx->req->content->on(upgrade => sub {
my ($single, $multi) = @_;
return unless $tx->req->url->path->contains('/upload');
# Subscribe to "part" event to find the right one
$multi->on(part => sub {
my ($multi, $single) = @_;
# Subscribe to "body" event of part to make sure we have all headers
$single->on(body => sub {
my $single = shift;
# Make sure we have the right part and replace "read" event
return unless $single->headers->content_disposition =~ /example/;
$single->unsubscribe('read')->on(read => sub {
my ($single, $bytes) = @_;
# Log size of every chunk we receive
app->log->debug(length($bytes) . ' bytes uploaded');
});
});
});
});
};
# Upload form in DATA section
get '/' => 'index';
# Streaming multipart upload
post '/upload' => {text => 'Upload was successful.'};
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head><title>Streaming multipart upload</title></head>
<body>
%= form_for upload => (enctype => 'multipart/form-data') => begin
%= file_field 'example'
%= submit_button 'Upload'
% end
</body>
</html>
use Mojolicious::Lite;
use EV;
use AnyEvent;
# Wait 3 seconds before rendering a response
get '/' => sub {
my $c = shift;
my $w;
$w = AE::timer 3, 0, sub {
$c->render(text => 'Delayed by 3 seconds!');
undef $w;
};
};
app->start;
Who actually controls the event loop backend is not important.
use Mojo::UserAgent;
use EV;
use AnyEvent;
# Search MetaCPAN for "mojolicious"
my $cv = AE::cv;
my $ua = Mojo::UserAgent->new;
$ua->get('fastapi.metacpan.org/v1/module/_search?q=mojolicious' => sub {
my ($ua, $tx) = @_;
$cv->send($tx->result->json('/hits/hits/0/_source/release'));
});
say $cv->recv;
You could, for example, just embed the built-in web server into an AnyEvent application.
use Mojolicious::Lite;
use Mojo::Server::Daemon;
use EV;
use AnyEvent;
# Normal action
get '/' => {text => 'Hello World!'};
# Connect application with web server and start accepting connections
my $daemon
= Mojo::Server::Daemon->new(app => app, listen => ['http://*:8080']);
$daemon->start;
# Let AnyEvent take control
AE::cv->recv;
use Mojo::UserAgent;
# Request a resource and make sure there were no connection errors
my $ua = Mojo::UserAgent->new;
my $tx = $ua->get('mojolicious.org/perldoc/Mojo' => {Accept => 'text/plain'});
my $res = $tx->result;
# Decide what to do with its representation
if ($res->is_success) { say $res->body }
elsif ($res->is_error) { say $res->message }
elsif ($res->code == 301) { say $res->headers->location }
else { say 'Whatever...' }
While methods like ``is_success'' in Mojo::Message::Response and ``is_error'' in Mojo::Message::Response serve as building blocks for more sophisticated REST clients.
use Mojo::UserAgent;
# Fetch website
my $ua = Mojo::UserAgent->new;
my $res = $ua->get('mojolicious.org/perldoc')->result;
# Extract title
say 'Title: ', $res->dom->at('head > title')->text;
# Extract headings
$res->dom('h1, h2, h3')->each(sub { say 'Heading: ', shift->all_text });
# Visit all nodes recursively to extract more than just text
for my $n ($res->dom->descendant_nodes->each) {
# Text or CDATA node
print $n->content if $n->type eq 'text' || $n->type eq 'cdata';
# Also include alternate text for images
print $n->{alt} if $n->type eq 'tag' && $n->tag eq 'img';
}
For a full list of available CSS selectors see ``SELECTORS'' in Mojo::DOM::CSS.
use Mojo::UserAgent;
use Mojo::URL;
# Fresh user agent
my $ua = Mojo::UserAgent->new;
# Search MetaCPAN for "mojolicious" and list latest releases
my $url = Mojo::URL->new('http://fastapi.metacpan.org/v1/release/_search');
$url->query({q => 'mojolicious', sort => 'date:desc'});
for my $hit (@{$ua->get($url)->result->json->{hits}{hits}}) {
say "$hit->{_source}{name} ($hit->{_source}{author})";
}
use Mojo::UserAgent;
my $ua = Mojo::UserAgent->new;
say $ua->get('https://sri:secret@example.com/hideout')->result->body;
use Mojo::UserAgent;
# User agent following up to 10 redirects
my $ua = Mojo::UserAgent->new(max_redirects => 10);
# Add a witty header to every request
$ua->on(start => sub {
my ($ua, $tx) = @_;
$tx->req->headers->header('X-Bender' => 'Bite my shiny metal ass!');
say 'Request: ', $tx->req->url->clone->to_abs;
});
# Request that will most likely get redirected
say 'Title: ', $ua->get('google.com')->result->dom->at('head > title')->text;
This even works for proxy "CONNECT" requests.
use Mojo::UserAgent;
use Mojo::Asset::File;
# Add "stream" generator
my $ua = Mojo::UserAgent->new;
$ua->transactor->add_generator(stream => sub {
my ($transactor, $tx, $path) = @_;
$tx->req->content->asset(Mojo::Asset::File->new(path => $path));
});
# Send multiple files streaming via PUT and POST
$ua->put('http://example.com/upload' => stream => '/home/sri/mojo.png');
$ua->post('http://example.com/upload' => stream => '/home/sri/minion.png');
The "json", "form" and "multipart" content generators are always available.
use Mojo::UserAgent;
# Send "application/json" content via PATCH
my $ua = Mojo::UserAgent->new;
my $tx = $ua->patch('http://api.example.com' => json => {foo => 'bar'});
# Send query parameters via GET
my $tx2 = $ua->get('search.example.com' => form => {q => 'test'});
# Send "application/x-www-form-urlencoded" content via POST
my $tx3 = $ua->post('http://search.example.com' => form => {q => 'test'});
# Send "multipart/form-data" content via PUT
my $tx4 = $ua->put(
'upload.example.com' => form => {test => {content => 'Hello World!'}});
# Send custom multipart content via PUT
my $tx5 = $ua->put('api.example.com' => multipart => ['Hello', 'World!']);
For more information about available content generators see also ``tx'' in Mojo::UserAgent::Transactor.
use Mojo::UserAgent;
# Fetch the latest Mojolicious tarball
my $ua = Mojo::UserAgent->new(max_redirects => 5);
my $tx = $ua->get('https://www.github.com/mojolicious/mojo/tarball/master');
$tx->result->save_to('mojo.tar.gz');
To protect you from excessively large files there is also a limit of 2GiB by default, which you can tweak with the attribute ``max_response_size'' in Mojo::UserAgent.
# Increase limit to 10GiB $ua->max_response_size(10737418240);
use Mojo::UserAgent;
# Upload file via POST and "multipart/form-data"
my $ua = Mojo::UserAgent->new;
$ua->post('example.com/upload' =>
form => {image => {file => '/home/sri/hello.png'}});
And once again you don't have to worry about memory usage, all data will be streamed directly from the file.
use Mojo::UserAgent; # Accept responses of indefinite size my $ua = Mojo::UserAgent->new(max_response_size => 0); # Build a normal transaction my $tx = $ua->build_tx(GET => 'http://example.com'); # Replace "read" events to disable default content parser $tx->res->content->unsubscribe('read')->on(read => sub { my ($content, $bytes) = @_; say "Streaming: $bytes"; }); # Process transaction $tx = $ua->start($tx);
The event ``read'' in Mojo::Content will be emitted for every chunk of data that is received, even chunked transfer encoding and gzip content encoding will be handled transparently if necessary.
use Mojo::UserAgent; # Build a normal transaction my $ua = Mojo::UserAgent->new; my $tx = $ua->build_tx(GET => 'http://example.com'); # Prepare body my $body = 'Hello World!'; $tx->req->headers->content_length(length $body); # Start writing directly with a drain callback my $drain; $drain = sub { my $content = shift; my $chunk = substr $body, 0, 1, ''; $drain = undef unless length $body; $content->write($chunk, $drain); }; $tx->req->content->$drain; # Process transaction $tx = $ua->start($tx);
The drain callback passed to ``write'' in Mojo::Content will be executed whenever the entire previous chunk of data has actually been written.
use Mojo::UserAgent;
use Mojo::IOLoop;
# Concurrent non-blocking requests
my $ua = Mojo::UserAgent->new;
$ua->get('https://metacpan.org/search?q=mojo' => sub {
my ($ua, $mojo) = @_;
say $mojo->result->dom->at('title')->text;
});
$ua->get('https://metacpan.org/search?q=minion' => sub {
my ($ua, $minion) = @_;
say $minion->result->dom->at('title')->text;
});
# Start event loop if necessary
Mojo::IOLoop->start unless Mojo::IOLoop->is_running;
But don't try to open too many connections to one server at the same time, it might get overwhelmed. Better use a queue to process requests in smaller batches.
use Mojo::UserAgent;
use Mojo::IOLoop;
my @urls = (
'mojolicious.org/perldoc/Mojo/DOM', 'mojolicious.org/perldoc/Mojo',
'mojolicious.org/perldoc/Mojo/File', 'mojolicious.org/perldoc/Mojo/URL'
);
# User agent with a custom name, following up to 5 redirects
my $ua = Mojo::UserAgent->new(max_redirects => 5);
$ua->transactor->name('MyParallelCrawler 1.0');
# Use a delay to keep the event loop running until we are done
my $delay = Mojo::IOLoop->delay;
my $fetch;
$fetch = sub {
# Stop if there are no more URLs
return unless my $url = shift @urls;
# Fetch the next title
my $end = $delay->begin;
$ua->get($url => sub {
my ($ua, $tx) = @_;
say "$url: ", $tx->result->dom->at('title')->text;
# Next request
$fetch->();
$end->();
});
};
# Process two requests at a time
$fetch->() for 1 .. 2;
$delay->wait;
It is also strongly recommended to respect every sites "robots.txt" file as well as terms of service, and to wait a little before reopening connections to the same host, or the operators might be forced to block your access.
use Mojo::UserAgent;
use Mojo::Promise;
# Synchronize non-blocking requests with promises
my $ua = Mojo::UserAgent->new;
my $mojo = $ua->get_p('https://metacpan.org/search?q=mojo');
my $minion = $ua->get_p('https://metacpan.org/search?q=minion');
Mojo::Promise->all($mojo, $minion)->then(sub {
my ($mojo, $minion) = @_;
say $mojo->[0]->result->dom->at('title')->text;
say $minion->[0]->result->dom->at('title')->text;
})->wait;
use Mojo::UserAgent;
use Mojo::Promise;
# Open WebSocket to echo service
my $ua = Mojo::UserAgent->new;
$ua->websocket_p('ws://echo.websocket.org')->then(sub {
my $tx = shift;
# Prepare a followup promise so we can wait for messages
my $promise = Mojo::Promise->new;
# Wait for WebSocket to be closed
$tx->on(finish => sub {
my ($tx, $code, $reason) = @_;
say "WebSocket closed with status $code.";
$promise->resolve;
});
# Close WebSocket after receiving one message
$tx->on(message => sub {
my ($tx, $msg) = @_;
say "WebSocket message: $msg";
$tx->finish;
});
# Send a message to the server
$tx->send('Hi!');
# Insert a new promise into the promise chain
return $promise;
})->catch(sub {
my $err = shift;
# Handle failed WebSocket handshakes and other exceptions
warn "WebSocket error: $err";
})->wait;
use Mojo::UserAgent;
use Mojo::Promise;
# GET request via UNIX domain socket "/tmp/foo.sock"
my $ua = Mojo::UserAgent->new;
say $ua->get('http+unix://%2Ftmp%2Ffoo.sock/index.html')->result->body;
# GET request with HOST header via UNIX domain socket "/tmp/bar.sock"
my $tx = $ua->get('http+unix://%2Ftmp%2Fbar.sock' => {Host => 'example.com'});
say $tx->result->body;
# WebSocket connection via UNIX domain socket "/tmp/baz.sock"
$ua->websocket_p('ws+unix://%2Ftmp%2Fbaz.sock/echo')->then(sub {
my $tx = shift;
my $promise = Mojo::Promise->new;
$tx->on(finish => sub { $promise->resolve });
$tx->on(message => sub {
my ($tx, $msg) = @_;
say "WebSocket message: $msg";
$tx->finish;
});
$tx->send('Hi!');
return $promise;
})->catch(sub {
my $err = shift;
warn "WebSocket error: $err";
})->wait;
You can set the "Host" header manually to pass along a hostname.
$ mojo get https://mojolicious.org 'head > title'
How about a list of all id attributes?
$ mojo get https://mojolicious.org '*' attr id
Or the text content of all heading tags?
$ mojo get https://mojolicious.org 'h1, h2, h3' text
Maybe just the text of the third heading?
$ mojo get https://mojolicious.org 'h1, h2, h3' 3 text
You can also extract all text from nested child elements.
$ mojo get https://mojolicious.org '#mojobar' all
The request can be customized as well.
$ mojo get -M POST -H 'X-Bender: Bite my shiny metal ass!' http://google.com
Store response data by redirecting "STDOUT".
$ mojo get mojolicious.org > example.html
Pass request data by redirecting "STDIN".
$ mojo get -M PUT mojolicious.org < example.html
Or use the output of another program.
$ echo 'Hello World' | mojo get -M PUT https://mojolicious.org
Submit forms as "application/x-www-form-urlencoded" content.
$ mojo get -M POST -f 'q=Mojo' -f 'size=5' https://metacpan.org/search
And upload files as "multipart/form-data" content.
$ mojo get -M POST -f 'upload=@example.html' mojolicious.org
You can follow redirects and view the headers for all messages.
$ mojo get -r -v http://google.com 'head > title'
Extract just the information you really need from JSON data structures.
$ mojo get https://fastapi.metacpan.org/v1/author/SRI /name
This can be an invaluable tool for testing your applications.
$ ./myapp.pl get /welcome 'head > title'
$ perl -Mojo -E 'say g("mojolicious.org")->dom->at("title")->text'
use Mojolicious::Lite;
use Mojo::Util 'secure_compare';
get '/' => sub {
my $c = shift;
# Check for username "Bender" and password "rocks"
return $c->render(text => 'Hello Bender!')
if secure_compare $c->req->url->to_abs->userinfo, 'Bender:rocks';
# Require authentication
$c->res->headers->www_authenticate('Basic');
$c->render(text => 'Authentication required!', status => 401);
};
app->start;
This can be combined with TLS for a secure authentication mechanism.
$ ./myapp.pl daemon -l 'https://*:3000?cert=./server.crt&key=./server.key'
$ mkdir myapp
$ cd myapp
$ touch myapp.pl
$ chmod 744 myapp.pl
$ echo '{name => "my Mojolicious application"};' > myapp.conf
Configuration files themselves are just Perl scripts that return a hash reference with configuration settings of your choice. All those settings are then available through the method ``config'' in Mojolicious and the helper ``config'' in Mojolicious::Plugin::DefaultHelpers.
use Mojolicious::Lite;
plugin 'Config';
my $name = app->config('name');
app->log->debug("Welcome to $name");
get '/' => 'with_config';
app->start;
__DATA__
@@ with_config.html.ep
<!DOCTYPE html>
<html>
<head><title><%= config 'name' %></title></head>
<body>Welcome to <%= config 'name' %></body>
</html>
Alternatively you can also use configuration files in the JSON format with Mojolicious::Plugin::JSONConfig.
$ mkdir -p lib/MyApp/Plugin $ touch lib/MyApp/Plugin/MyHelpers.pm
They work just like normal plugins and are also subclasses of Mojolicious::Plugin. Nested helpers with a prefix based on the plugin name are an easy way to avoid conflicts.
package MyApp::Plugin::MyHelpers;
use Mojo::Base 'Mojolicious::Plugin';
sub register {
my ($self, $app) = @_;
$app->helper('my_helpers.render_with_header' => sub {
my ($c, @args) = @_;
$c->res->headers->header('X-Mojo' => 'I <3 Mojolicious!');
$c->render(@args);
});
}
1;
You can have as many application specific plugins as you like, the only difference to normal plugins is that you load them using their full class name.
use Mojolicious::Lite;
use lib 'lib';
plugin 'MyApp::Plugin::MyHelpers';
get '/' => sub {
my $c = shift;
$c->my_helpers->render_with_header(text => 'I ♥ Mojolicious!');
};
app->start;
Of course these plugins can contain more than just helpers, take a look at ``PLUGINS'' in Mojolicious::Plugins for a few ideas.
package Mojolicious::Command::spy;
use Mojo::Base 'Mojolicious::Command';
has description => 'Spy on application';
has usage => "Usage: APPLICATION spy [TARGET]\n";
sub run {
my ($self, @args) = @_;
# Leak secret passphrases
if ($args[0] eq 'secrets') { say for @{$self->app->secrets} }
# Leak mode
elsif ($args[0] eq 'mode') { say $self->app->mode }
}
1;
Command line arguments are passed right through and there are many useful attributes and methods in Mojolicious::Command that you can use or overload.
$ mojo spy secrets HelloWorld $ ./script/myapp spy secrets secr3t
And to make your commands application specific, just add a custom namespace to ``namespaces'' in Mojolicious::Commands and use a class name like "MyApp::Command::spy" instead of "Mojolicious::Command::spy".
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Add another namespace to load commands from
push @{$self->commands->namespaces}, 'MyApp::Command';
}
1;
The options "-h"/"--help", "--home" and "-m"/"--mode" are handled automatically by Mojolicious::Commands and are shared by all commands.
$ ./script/myapp spy -m production mode production
For a full list of shared options see ``SYNOPSIS'' in Mojolicious::Commands.
$ mojo generate lite_app myapp.pl
$ ./myapp.pl eval 'say for @{app->static->paths}'
$ ./myapp.pl eval 'say for sort keys %{app->renderer->helpers}'
The "verbose" options will automatically print the return value or returned data structure to "STDOUT".
$ ./myapp.pl eval -v 'app->static->paths->[0]' $ ./myapp.pl eval -V 'app->static->paths'
$ mojo generate app MyApp $ cd my_app $ mv public lib/MyApp/ $ mv templates lib/MyApp/
The trick is to move the "public" and "templates" directories so they can get automatically installed with the modules. Additionally author commands from the "Mojolicious::Command::Author" namespace are not usually wanted by an installed application so they can be excluded.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
use Mojo::File 'path';
use Mojo::Home;
# Every CPAN module needs a version
our $VERSION = '1.0';
sub startup {
my $self = shift;
# Switch to installable home directory
$self->home(Mojo::Home->new(path(__FILE__)->sibling('MyApp')));
# Switch to installable "public" directory
$self->static->paths->[0] = $self->home->child('public');
# Switch to installable "templates" directory
$self->renderer->paths->[0] = $self->home->child('templates');
# Exclude author commands
$self->commands->namespaces(['Mojolicious::Commands']);
my $r = $self->routes;
$r->get('/welcome')->to('example#welcome');
}
1;
Finally there is just one small change to be made to the application script. The shebang line becomes the recommended "#!perl", which the toolchain can rewrite to the proper shebang during installation.
#!perl
use strict;
use warnings;
use FindBin;
BEGIN { unshift @INC, "$FindBin::Bin/../lib" }
use Mojolicious::Commands;
# Start command line interface for application
Mojolicious::Commands->start_app('MyApp');
That's really everything, now you can package your application like any other CPAN module.
$ ./script/my_app generate makefile $ perl Makefile.PL $ make test $ make manifest $ make dist
And if you have a PAUSE account (which can be requested at <http://pause.perl.org>) even upload it.
$ mojo cpanify -u USER -p PASS MyApp-0.01.tar.gz
use Mojolicious::Lite;
any {text => 'Hello World!'};
app->start;
It works because all routes without a pattern default to "/" and automatic rendering kicks in even if no actual code gets executed by the router. The renderer just picks up the "text" value from the stash and generates a response.
$ perl -Mojo -E 'a({text => "Hello World!"})->start' daemon
And you can use all the commands from Mojolicious::Commands.
$ perl -Mojo -E 'a({text => "Hello World!"})->start' get -v /