NAME¶
Mojolicious::Guides::FAQ - Frequently Asked Questions
OVERVIEW¶
This document contains the most frequently asked questions about Mojolicious
together with the right answers.
QUESTIONS¶
How does Mojolicious compare to other Perl web frameworks?¶
The short answer is "it doesn't", because we interpret the words
"web framework" much more literally than others. With the emergence
of the "real-time web" and new technologies such as
"WebSockets", we are facing new challenges that go way beyond what
commonly used modules like LWP were designed for. Because of this, Mojolicious
contains a whole new HTTP client/server stack called Mojo, which was heavily
inspired by the original "LWPng" effort and carefully designed with
these new requirements in mind. So while some of the higher abstraction layers
might look similar to other web frameworks, it actually defines a whole new
category and could even be the foundation for more advanced ones in the
future.
Why doesn't Mojolicious have any dependencies?¶
We are optimizing Mojolicious for user-friendliness and development speed,
without compromises. While there are no rules in
Mojolicious::Guides::CodingGuidelines that forbid dependencies, we do
currently discourage adding non-optional ones in favor of a faster and more
painless installation process. And we do in fact already use several optional
CPAN modules such as EV, IO::Socket::INET6, IO::Socket::SSL and Plack to
provide advanced functionality if they are installed.
Why reinvent wheels?¶
Because we can make them rounder. Components specifically designed for
user-friendliness and development speed are not easy to come by. We are strong
believers of the Perl mantra "There is more than one way to do it.",
and our quest is to develop the best possible solutions for these two
criteria.
What about backwards compatibility?¶
In conformance with Mojolicious::Guides::CodingGuidelines, we will always
deprecate a feature before removing or changing it in incompatible ways
between major releases. New features can however be marked as experimental to
explicitly exclude them from these rules. This gives us the necessary freedom
to ensure a healthy future for Mojolicious. So, as long as you are not using
anything marked experimental, untested or undocumented, you can always count
on backwards compatibility, everything else would be considered a bug.
Why not split up Mojolicious into many smaller
distributions?¶
Because there are no advantages, it drastically increases maintenance costs and
installation times without giving us anything in return. It would only make
sense if we wanted to pass ownership of a module to a new maintainer, which we
already have done in the past.
Can you add feature XY to the core distribution?¶
Probably not. While the Mojolicious distribtion covers a wide range of features,
we are rather conservative when it comes to adding new ones. The most
important criteria are outlined in Mojolicious::Guides::CodingGuidelines. But
don't let this discourage you, it doesn't hurt to open a GitHub issue
<
https://github.com/kraih/mojo/issues> and ask, just be prepared that it
might not pass the vote. To increase the chances you can also discuss and
refine ideas on the mailing-list
<
http://groups.google.com/group/mojolicious>.
What does the error "Maximum message size exceeded."
mean?¶
To protect your applications from excessively large requests and responses, our
HTTP parser has a cap after which it will automatically stop accepting new
data, and in most cases force the connection to be closed. This limit is
around "5MB" by default, you can use the
"MOJO_MAX_MESSAGE_SIZE" environment variable to change this value.
What does the error "Maximum line size exceeded."
mean?¶
This is a very similar protection mechanism to the one described in the previous
answer, but a little more specific. It limits the maximum length of any
"\r\n" terminated part of a HTTP message, such as request line,
status line and headers. This limit is around "10KB" by default, you
can use the "MOJO_MAX_LINE_SIZE" environment variable to change this
value.
What does "Your secret passphrase needs to be
changed!!!" mean?¶
Mojolicious uses a secret passphrase for security features such as signed
cookies. It defaults to the name of your application, which is not very
secure, so we added this log message as a reminder. You can change the
passphrase with the attribute "secret" in Mojolicious.
app->secret('My very secret passphrase.');
What does "Inactivity timeout." mean.¶
To protect your applications from denial-of-service attacks, all connections
have an inactivity timeout which limits how long a connection may be inactive
before being closed automatically. It defaults to 20 seconds for the user
agent and 15 seconds for all built-in web servers, and is commonly referred to
as "inactivity_timeout". This timeout always applies, so you might
have to tweak it for applications that take a long time to process a request.
What does "Premature connection close." mean?¶
This error message is often related to the one above, and means that the web
server closed the connection before the user agent could receive the whole
response.
What does "Worker 31842 has no heartbeat, restarting."
mean?¶
Hypnotoad worker processes send heartbeat messages to the manager process in
regular intervals to signal that they are still responsive. A blocking
operation such as an infinite loop in your application can prevent this, and
will force the affected worker to be restarted after a timeout. This
"heartbeat_timeout" defaults to 20 seconds and can be extended if
your application requires it.
I think i have found a bug, what should i do now?¶
First make sure you are using the latest version of Mojolicious, it is quite
likely that the bug has already been fixed. If that doesn't help, prepare a
test case demonstrating the bug, you are not expected to fix it yourself, but
you'll have to make sure the developers can replicate your problem. Sending in
your whole application generally does more harm than good, the "t"
directory of this distribution has many good examples for how to do it right.
Writing a test is usually the hardest part of fixing a bug, so the better your
test case the faster it can be fixed. ;)
Once that's done you can contact the developers via GitHub issue
<
https://github.com/kraih/mojo/issues>.
If you decide to fix the bug yourself, make sure to also take a look at
Mojolicious::Guides::CodingGuidelines.
MORE¶
You can continue with Mojolicious::Guides now or take a look at the Mojolicious
wiki <
http://github.com/kraih/mojo/wiki>, which contains a lot more
documentation and examples by many different authors.