Another year of dancing

It's been a while since we had an advent calendar. It's about time.

You might be wondering what we've been up to in the last year. Well, a lot.

New members
Please welcome two new core team members:
- Peter (@SysPete) Mottram
  If you have raised an issue, you have likely interacted with Peter. He takes care of the queue, co-organizes the conferences, and managed the entire transition to the new plugin architecture, helping authors by testing their code and transitioning the syntax.
  
  Oh, new plugin architecture? More to follow.
- Jason (@CromeDome) Crome
  Jason Crome started by fixing up the documentation and moved on to help with the releases themselves. If you looked up Dancer2 recently on CPAN, you probably recognize his picture by now. :)
  
  Jason's handling of the releases allows us to maintain a higher quality of releases, including timing, announcements, and double checking the important Pull Requests and issues are resolved prior to the release.
New features
- Asynchronous streaming responses
  We have finally introduced the ability to provide asynchronous and streaming responses. This allows you to do various interesting things, but it can be quite complex.
  
  This topic has its own article in this year's advent calendar. Stay tuned!
- prefix supports the route spec
  The prefix syntax allowed you to reduce the repeated parts of strings, and it now supports the full spec in order to allow you to reduce the pattern strings:
```
prefix '/:action' => sub {
    get '/:entity' => sub {...};
};
```
- send_file is now streaming
  The send_file keyword will now also stream the response asynchronously if it's available. You don't need to think about it. You don't even know it does it, but it does, automatically, or you. :)
- New keywords
  - New parameters keywords
    We have introduced new keywords to retrieve information from the route, query, or body parameters. They help handle common incorrect and risky patterns.
    
    They will also appear in their own advent article. Stay tuned!
  - New header keywords
    Noticing we only have headers to handle the response headers, we have introduced several keywords to help you handle the request headers.
    - request_header.
      Return the request header.
    - response_header.
      A more explicit alternative to header.
    - response_headers.
      A more explicit alternative to headers.
    - push_response_header.
      A more explicit alternative to push_header.
    You will notice you cannot push a request header. This is on purpose, since request headers should not change, they only represent the request you received.
    
    (We might eventually deprecate the general header and push_header keywords.)
  - send_as
    The send_as keyword gets around the serializer.
    
    Interested? It has its own advent article!
  - Local config files
    You can now provide additional local configuration files that will be loaded, but can be kept out of a version control repository.
    
    Stay tuned for an article on that!
  - New config option change_session_id
    We have added a configuration option for improved security in cookies. We will feature an article on them as well.
  - New keywords encode_json, decode_json
- template keyword global
  The template keyword can now be used outside a request. The relevant request-specific variables will not be available (since it's outside a request), but everything else will be available.
- eval shim
  You now have a shim for eval behavior. If you need such an option, you already understand what it means.
- Support 304 Not Modified
  We properly support 304 Not Modified when serving static files.
New documentation
We have revamped our documentation.

The original documentation had irrelevant parts from Dancer 1 which no longer apply to Dancer 2, outdated components, unclear and confusing descriptions, and quite honestly, were hard to navigate.

The rewritten documentation focus on clarifying how a Dancer 2 program is constructed, the definitions we use and what they mean, the important keywords, and how to use the syntax.

It does not delve into deprecated patterns, nor does it explain it. The reasoning is that you could find it if you search, but we don't want to teach you what you shouldn't be doing.

Documentation is a live project at any given time and our documentation is no different. This means we always need additional help with it. If you find something to improve, please let us know. We would appreciate your help.
Memory leaks sealed
We have become better at identifying memory leaks and resolved a few important ones. We've also added various tests to improve our detection, which so far yield no additional ones.
Speedups
Prompted by a user mentioning they still use Dancer 1 because it is faster, we have pushed hard and sped up Dancer 2 by quite a bit. It now does not match Dancer 1, but surpasses it.

Here are some of the specific work we did:
- Optimized routing
  The routing itself has been optimized. We have a few more plans for this part, but it is now faster and better.
- Fewer layers, fewer dependencies
  We removed various layers (such as Middlewares) and removed some dependencies in order to get more direct access to faster components.
  
  We're learning where we can push more against abstractions and when we need to use them despite possible slower performance.
- Better request object
  Our request object has been rewritten. It was originally our own custom object, written from scratch, but now it subclasses the useful Plack::Request while adding Dancer-specific bits or components that were rejected from being included in the basic Plack class.
- Faster headers
  We now internally use a faster header library, which is also used by Plack itself: HTTP::Headers::Fast. We recommend using HTTP::XSHeaders which we co-authored, which will speed your headers substantially.
- Faster cookies
  We will optionally use HTTP::XSCookies if it's available in order to speed up the cookie handling.
- Faster serializers and config loader
  The JSON serializer will use JSON::MaybeXS which will optionally use an XS implementation of JSON, if available.
DancerConf 2015 and DancerConf 2016
We have held two conferences over the last two years.

While we're still working on the videos for DancerConf 2016, you can already find the videos for DancerConf 2015 on YouTube!.
New plugin architecture
The plugin architecture in Dancer 2 was one of the big remaining weak points. We had to resolve it.

It had now been completely rewritten, and it has its own advent article in this calendar!

Author

This article has been written by Sawyer X for the Perl Dancer Advent Calendar 2016.

Copyright

No copyright retained. Enjoy.

Sawyer X.

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Another year of dancing

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