What is this Dancer anyway?

By Christian Pietsch

Today a colleague with a background in PHP and CGI scripting asked me, “What is this Dancer thing you keep bringing up?”

Me: Dancer is a microframework for web development in Perl, like Mojolicious. What Sinatra is for Ruby, or Flask or Bottle for Python.

He: ???

Me: It has a built-in web server. In contrast to PHP or CGI scripts, you can use one file with Perl code to define what should happen when different URLs are requested. It’s like a collection of if–then rules with a URL pattern to the left and the associated action to the right.

He: Why would I want that?

Me: These rules can be quite compact, giving you a nice overview of what your web application does (its REST API, if you will). More importantly, this approach allows you to decouple the URL layout from your program logic. In contrast to Ruby on Rails or Django, Dancer does not enforce a strict MVCarchitecture, but keeping to MVC principles is dead easy using Dancer, if you want to. Details of the view can be left for the templating system to deal with.

He: A templating system? Sounds complicated.

Me: Not at all. Writing templates is much like writing PHP, but simpler. It’s basically an HTML file with some placeholders in it. Web designers love it. Some of them can even be tricked into using the limited control structures (IF, FOREACH, etc.) offered by templating engines – realizing only later that they have started to do programming.

He: So why are they called microframeworks? Are they for toy projects only?

Me: Certainly not. Perhaps the name came up because overly complicated web frameworks such as Zope and all that Java Enterprise stuff had given web frameworks and web application servers a bad name. Microframeworks are leaner and do not force programmers into a straightjacket.

He: So why are my favourite open-source web applications all written in PHP?

Me: I have honestly no idea.

He: Does Dancer make it easy to integrate a database and a search engine into my web app? I need to create a SCRUD web app for searching, creating, reading, updating and deleting data records.

Me: No. Perhaps this is why it is a called a microframework. But if you add Catmandu into the mix, you get exactly what you want. How about heading over to the Catmandu tutorial? The second part, Dancer & Catmandu: Writing web applications should be easy and fun teaches you exactly what you need to know.


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