Cloning Internet Applications with Ruby: Make clones of some of the best applications on the Web using the dynamic and object-oriented features of Ruby

Internet applications dont always need to be full of features or cover all aspects of your Internet life to be successful. Sometimes it's ok to be simple and just focus on providing a single feature. It doesn't even need to be earth-shatteringly important—it should be just useful enough for its target users. The archetypical and probably most extreme example of this is the URL shortening application or URL shortener.

This service offers a very simple but surprisingly useful feature. It provides a shorter URL that represents a normally longer URL. When a user goes to the short URL, he will be redirected to the original URL. For this simple feature, top three most popular URL shortening services (TinyURL, bit.ly, and is.gd) collectively had about 11 million unique visitors, 110 million page views and a reach of about 1% of the Internet in June 2009. In 2008, the most popular URL shortener at that time, TinyURL, was made one of Time Magazine's Top 50 Best Websites.

The...

Next, let's list down the features of a URL shortener. In subsequent chapters we will go down similar paths with each popular Internet application. The intention in this section is to distill the basic features of the application, features that define the service. Features listed here will be features that make the application what it is.

However, as much as possible we want to also explore some additional features that extend the application and are provided by many of its competitors. Most importantly, the features here are mostly features of the most popular and definitive web application in the category. In this chapter, this will be TinyURL.

These are the main features of a URL shortener:

Cloning TinyURL is relatively simple but there is some thought behind the design of the application. We will be building a clone of TinyURL called Tinyclone, which will be hosted at the domain http://tinyclone.saush.com.

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.

Finally we get to the meat of the chapter. Here we roll up our sleeves and get to the business of coding Tinyclone. The overall web application is around 200 lines of code, so we will put everything into a single file called tinyclone.rb. With a bit of Sinatra magic this becomes our entire web application.

We will be looking at Tinyclone from two simple perspectives. The first is the data model. The data model is an abstract view of the objects that are used to represent the application problem space. The second is the application flow, which describes how the application uses the data model to provide the functions needed. As the application isn't very large, we can inspect its code in detail, something we will not be able to do in later chapters when we deal with larger applications.

There are a few ways to run the Sinatra web application. The simplest is probably to run it off the command line. To do this, we need to set up the database. We assume that for this application you would have installed MySQL. At the command line go into the MySQL interactive command console:

$ mysql –u <username> -p <password>

Then just execute the following command:

mysql> create database tinyclone;

This will just create the database. Next, go into IRB and run this command:

> require 'tinyclone'

This will require the necessary classes for creating the database tables. Next, just run this command:

> DataMapper.auto_migrate!

This will create the tables for the application. To run the application, we just need to run this at the command line:

$ ruby tinyclone.rb

Then, go to http://localhost:4567/ and you will see the running application:

This is how the info page looks:

Alternatively we can also deploy to Heroku, the Ruby cloud-computing platform. Deploying...

This is just a warm-up. In this chapter, we cloned one of the simplest popular Internet applications around, TinyURL. Later applications will gradually get more complicated. We started off the chapter with a general introduction to URL shorteners and a list of pros and cons of using URL shorteners. Then we listed the main features and discussed the design of our URL shortener, called Tinyclone. This set the foundation for the discussion on actual construction of the application. After designing our clone, we went briefly into a short refresher on the technologies used before going into detail on how the application was built.

The chapter broke up the application into a data model and an application flow discussion. Both parts were discussed and explained in detail. Finally, we ended the chapter with a description of how Tinyclone can be deployed. We discussed two options for deployment—one to a normal server (simulated locally) by running it off the command line and the other to Heroku...