We will use a number of technologies in this chapter, mainly revolving around the Ruby programming language and its various libraries. The main Ruby technologies have been discussed in detail in Chapter 1, Cloning Internet Applications, and this section is a refresher before we jump into the code discussion.
Sinatra is a Domain Specific Language (DSL) for quickly creating web applications in Ruby. It keeps a minimal feature set for developers and is an excellent tool for creating small to mid-sized web applications using Ruby.
We discussed Sinatra in depth in Chapter 1.
Haml (HTML Abstraction Markup Language) is a simple markup language that is used to cleanly describe HTML in a web page. Haml was originally built for Ruby but has also been ported to other languages and platforms. We discussed Haml in depth in Chapter 1.
DataMapper is an object-relational mapping library for Ruby. While there are a number of Ruby object-relational mapping libraries, DataMapper has a number of good features. It is independent and doesn't tie in with any particular frameworks. It is also built to be fast and efficient, often delaying interacting with the data store until it is needed. It is also very Ruby centric and fits in well with the rest of the technologies that we use in the book.
We discussed DataMapper in depth in Chapter 1.
Blueprint CSS is a simple and effective CSS framework. It provides a basic set of CSS styles that makes developing web applications much easier. One of its most useful features is a set of grid layout styles that allows simple to complex layouts to be created easily and effectively. Used together with HAML, it allows us to create great looking front-ends for our web applications.
While the main features in the applications are all implemented within the chapters itself, sometimes we still depend on other services provided by generally well-known providers. In this chapter we use two services—Google Chart API for visualizing the statistics we gather on the short URLs and HostIP to geocode IP addresses we get.
The Google Chart API provides its users a means of dynamically generating various types of charts. In this chapter, we use the Google Chart API to generate statistics visualizations, specifically bar charts and maps.
The Google Chart API returns a PNG-format image in response to a URL. Several types of image can be generated, and for each image type, you can specify attributes such as size, colors, and labels. The Google Chart API is not rate-limited but Google advises users to let them know if they use more than 250,000 API calls per day.
HostIP is a free service that provides geocoding services based on IP addresses. Its usage is very simple—we just need to call a HostIP URL with an IP address and it will return geocoded information on the IP address. HostIP is a community-based project that gets its data from its users so accuracy is not perfect. However, for our purpose it is good enough.
Heroku is a Ruby-specific cloud-computing platform that provides specialized Ruby hosting services for developers. It allows Ruby developers to easily and almost instantly deploy web applications to the Internet. Heroku supports Rack-based web applications so deploying our Sinatra applications to Heroku is a breeze. While Heroku charges for hosting, it also provides a free basic tier account. More information on how Heroku is used at the end of this chapter when we talk about deployment.