Entries Tagged 'ruby' ↓

SocialDevCamp East Returns!

SocialDevCamp East Fall 2008

In May, several of us put together SocialDevCamp East at University of Baltimore.  It was an incredible day, filled with deep technical content as well as excellent discussions of business strategy and the very real challenges that east coast companies face breaking into the consumer-facing Internet space.

The day was universally hailed as a success, and maybe even a little bit of a breakthrough: for the first time, the “Amtrak corridor” tech communities had come together to face the challenges of the future together as a unified ecosystem, not just as individuals.  The result was a phenomenal mixing of technical, business, and artistic topics and in my mind, was a glimpse of the future.

So, we’re back at it on November 1st, 2008.  You can sign up on the barcamp wiki or on Facebook.

We’re looking forward to another great event, and another awesome afterparty at Brewer’s Art.  Go ahead and start your juices flowing for what sessions you would like to see, and post them to the Wiki.

We’re also looking for sponsors for both the event and the after party.  To find out more, please contact us.

See you in November in Baltimore!

Twittervision API Changes

When we first launched Twittervision in early 2007, Twitter was still a pretty small community of users (around 200,000) and only the press and the digerati were paying much attention to it.

Today, with just over 1M users, Twitter is still pretty small by Internet standards, but a lot of people are paying attention to it.

Our API was designed to allow individual users to use the Twittervision location features. A lot of people are using it. We also had a fair number of people who were using our API as an alternative to the Twitter API and trying to harvest vast amount of data using our free API.

Sadly, this was restricting service to others, so we are making some changes to the API that make this kind of use no longer possible. Those of you using the API for your individual projects or in support of client-side apps will see no changes for now — keep doing what you’re doing.

We do sometimes engage in licensing agreements, however, so if you are interested in licensing our data, please contact me at dave at twittervision.com.

ActsAsRenderer Brings Output to Models

Judging by the fact that there are several posts about this topic out in the wild, and that I have come across a need for it more than once, I thought it would be helpful to wrap up this functionality into a plugin and put it out into the world. Give a warm welcome to ActsAsRenderer!

Before you go off on a tirade about the evils of violating MVC, let me first say I know the arguments and I agree with you. However, in a world of complex systems where not everything is done via full-stack HTTP, there are legitimate reasons to output data directly from models, and ActsAsRenderer helps you do it.

With ActsAsRenderer, you get four cool new functions.

For your model class, you get render_file and render_string. For your instances, you get render_to_file and render_to_string.

Probably the most common (and legitimate) use of this kind of functionality is for rendering data out of a Rails script (say with script/runner). Since that environment is not a full-stack HTTP view of the world, it’s a real pain to render any kind of structured output. Not anymore! With acts_as_renderer in your model, you can render your views and give your model the voice it’s been lacking!

I’ve had this need come up several times. Most recently, I built a server configuration management system using Rails. While it is nice to preview the rendered configuration files using Rails-over-HTTP, it is also essential to be able to write those same configuration files out to the filesystem. In another case, I had a background DRb process that needed to be able to render templated output to the filesystem. I had to go build a mock-controller and do some pretty unsavory things; all of that would have been obviated with acts_as_renderer.

Now, I can simply say:

class Server < ActiveRecord::Base  acts_as_renderer

  def build_configuration    CLIENT_CONFIG_FILES.each do |f|      render_to_file("configs/#{f}", "#{config_dir}/#{f}.conf")    end  endend

The render_to_file function renders the templates located in configs (under app/views by default) and writes them to the files specified in the config_dir; it’s also smart enough to know that render_to_file is being called from a ‘server’ instance and sets @server accordingly. So my templates in configs are simply:

; Configuration Snippet for Server <%=@server.description%>

<%= render :partial => 'configs/queue', :collection => @server.queues %>

Please do think before using this plugin. It can be used for some seriously evil violations of good MVC design practice, and you are responsible for your own actions. However, this can also be used to make your existing designs *much* more robust and elegant, and I encourage you to use it where that is true.

It’s ready to drop in. Everything is there, including tests. Enjoy!

NOTE: Version 1.0 only supported Rails 2.0; I just added version 1.01 which will work with either Rails 1.2.x or 2.0.x. Please feel free to ping me with any questions.

acts_as_renderer at RubyForge

Automatic Asset Minimization and Packaging with Rails 2.0.x

With the recent release of Rails 2.0, many of us are reviewing our approaches to common problems. Many new features have been added to Rails, and some old tricks are either no longer necessary or no longer work.

I am developing a project with Rails 2.0 and am getting close to putting it into production. A recurring issue for today’s web developers is that of asset packaging, or the combination of multiple site assets into a single file. Specifically, we’re talking about Javascript and CSS.

A given “Web 2.0” (a term I wish had recently been found dead in a cramped apartment in Brooklyn) site might have a half dozen Javascript or CSS files to deliver to a user, and web browsers are not all that efficient at retrieving them. Each one requires a separate TCP connection to the server, and many browsers are only capable of getting two of these files concurrently. This means delays for your users.

In Rails 2.0 (and previously in Edge Rails), it’s possible to combine multiple Javascript and CSS files using the javascript_include_tag and stylesheet_link_tag functions in your html.erb files; simply add :cache => true to the parameters like this:

<%= javascript_include_tag 'prototype', 'effects', :cache => true %><%= stylesheet_link_tag 'main', 'shop', 'form', :cache => true %>

With :cache => true and when running in your production environment, Rails will automatically combine your Javascript and CSS assets into single files (all.js and all.css, respectively) and significantly reduce your site’s load time.

However, this really only solves part of the problem. A common technique used to further improve site performance is to compress Javascript and CSS by removing unnecessary whitespace and comments. I am not sure why this wasn’t included as part of Rails’ built-in caching features, but it seemed to me it should be easy to add.

Turns out I was mostly right. Google “javascript minimization” (or minification) and you’ll see it’s a pretty hot topic. The Asset Packager plugin from Scott Becker does this, as well as CSS compression, but is targeted at Rails 1.x and doesn’t really make sense in the face of Rails 2.0.

So I set out to solve this problem in an elegant way for Rails 2.0. Asset Packager uses a Ruby script called jsmin.rb by Uladzislau Latynski which is based on jsmin.c by Douglas Crockford. The thing is, jsmin.rb is not a class or library, but rather a standalone executable that operates on stdin and stdout. Asset Pacakger actually forks a ruby shell process to do its Javascript minimization, and this seemed like folly if it could be done internal to Rails.

Accordingly, I modified jsmin.rb to operate as a singleton class and with a class method you could pass Javascript data to. Then it was simply a matter of monkey patching this function into ActionView::Helpers::AssetTagHelper, home of javascript_include_tag and stylesheet_link_tag.

I also wanted to add in CSS compression, which turned out to be easy. The javascript_include_tag and stylesheet_link_tag functions both use the same underlying functions to package their assets, so it was a simple case of replacing them with equivalents that do compression appropriately, based on whether we are dealing with CSS or JS.


module ActionView  module Helpers    module AssetTagHelper      require 'jsminlib'

      def compress_css(source)        source.gsub!(/\s+/, " ")           # collapse space        source.gsub!(/\/\*(.*?)\*\/ /, "") # remove comments        source.gsub!(/\} /, "}\n")         # add line breaks        source.gsub!(/\n$/, "")            # remove last break        source.gsub!(/ \{ /, " {")         # trim inside brackets        source.gsub!(/; \}/, "}")          # trim inside brackets      end

      def get_file_contents(filename)        contents = File.read(filename)        if filename =~ /\.js$/          JSMin.minimize(contents)        elsif filename =~ /\.css$/          compress_css(contents)        end      end

      def join_asset_file_contents(paths)        paths.collect { |path|          get_file_contents(File.join(ASSETS_DIR, path.split("?").first)) }.join("\n\n")      end

    end  endend

By simply modifying join_asset_file_contents to use our new function get_file_contents instead of File.read, we quickly get to the heart of the matter. CSS files get compress_css run on them, while Javascript files get JSMin.minimize run on them. Your :cache => true Javascript and CSS assets will now be gloriously combined and compressed!

Note that the above monkey patch requires jsminlib.rb, which you can download here. It is just a modified version of the original jsmin.rb, and you will want to put it into your Rails lib directory.

A good next step would be to further enhance get_file_contents to do Javascript obfuscation, which allows for the replacement of variable names and thus even further compression; it also tends to make Javascript code nearly incomprehensible and thus harder to steal, which may be desirable for some developers. I haven’t found any native Ruby ways to do this yet, but it seems to me that this would be a good place for a C extension (or similar), and that this should all be put into a tiny and lightweight plugin.

I’m always amazed at how easy it is to bend Rails (and Ruby) to one’s will, and in this case it’s really quite elegant and straightforward. I’d love to hear your ideas about how to take this idea forward, potentially even including it in Rails itself.

Download the files here: