Building Calliope – Services Design

If you don’t know what Calliope is, please read this other post before continuing on.

In this post I’m going to describe how the web services forming the backend of Calliope have been designed and built. I didn’t concentrate much on designing them because I was eager to reach a visual result, so I know they’re not the best possible; I’m open to criticism and I hope with your help to improve the design.

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Building Calliope – Index

Update (19/4/2011): New screenshots and Todo list of first preview

In the last post I introduced my latest effort: Calliope. As a further step I want to share with you a little more about the challenges and problems of the project, and about the solutions I came up with. Here is what I am going to write about:

  • Data model – how the game is represented in SQL tables, and how this relates to real-time problems;
  • Services Design – how the data model is being published by a series of RESTful web services;
  • The Server – building the services to serve data using symfony 2;
  • Sproutcore data sources – getting access to the data from the client;
  • Sproutcore and Rapahel – something about the integration layer I built among the two libraries;
  • Building the board – a little insight on how the game board – the main component of the client – has been built;
  • Real-time magic – how real-time playing is ultimately achieved in the client.

I am going to publish one post (or more) for each point in the list, about once a week. If you have preferences about what topic I should cover first or questions about the project, just let me know in the comments (or even in private if you prefer) and I’ll do my best to answer.

Introducing Calliope

Recently I felt the need to share more of my “private projects”, so that someone else passing by can read about them and maybe find them interesting. My hope is that by making more things public I can get more motivated to continue on and not let those projects die.

For those reasons, I’m introducing to you my latest project: Calliope.

Calliope is a word game similar to Scrabble, but with a twist. It is played by two or more players, with every player having 7 lettered tiles on a rack; points are scored by placing them on a board to form existing words. The twist that I added to the game is that during your turn you can use all the letters already on the board, that is: you can grab them and move them around at your wish to form new words (I grabbed the idea from a popular – in Italy – card game called Macchiavelli); you however only receive points for the words in which you put at least one of your rack’s letters.

In the same period I “invented” Calliope by merging Scrabble and Macchiavelli I was discovering the existence of new web frameworks and technologies that I would have liked to experiment with. Since at that time I hadn’t a “private project” going on I decided to start one on Calliope itself, and to implement a digital version of the game based on web technologies.

Here is a sneak peak of the result at current stage of development:

Update: more screenshots here!

It is essentially a multiplayer real-time game, in which two or more players can interact with the board in turn. As you can see there’s the rack on the bottom of the page, and there’s a chat on the right with which one can communicate with the other players. Here is how it is constructed:

  • the client side – portraid in the picture – is made on top of Sproutcore, a javascript framework aimed to build desktop-like applications, great stuff;
  • the graphic part (essentially, the board) has been built using Raphael, which gives a nice and smooth javascript interface to SVG programming – I integrated it with Sproutcore myself;
  • the back of the house/server side is built on top of symfony 2, a blazing fast any-purpose php framework.

At the beginning of the project I had no idea of how Sproutcore, Raphael or symfony 2 worked; it has been – and will be – an opportunity for me to learn them. By the way, I also experimented on two other things: RESTful web services (to prepare for the topic I also read this book by Richardson and Ruby) and git, which I never tried before.

At current stage of development, the game is playable but not really stable, and there are still a number of open things to be done. However, I am hoping to put a demo online as soon as possible, to show you more of the project.

This was only an introduction, stay tuned for more! 🙂

Update: this post has become the first of a series of posts about Calliope, you can find the index here.