Cheapest way (platform/language) to implement a RESTful web API for an iPhone app?

Question

I am developing an iPhone app and would like to create some sort of RESTful API so different users of the app can share information/data. To create a community of sorts.

Say my app is some sort of game, and I want the user to be able to post their highscore on a global leaderboard as well as maintain a list of friends and see their scores. My app is nothing like this but it shows the kind of collective information access I need to implement.

The way I could implement this is to set up a PHP and MySQL server and have a php script that interacts with the database and mediates the requests between the DB and each user on the iPhone, by taking a GET request and returning a JSON string.

Is this a good way to do it? Seems to me like using PHP is a slow way to implement this as opposed to say a compiled language. I could be very wrong though. I am trying to keep my hosting bills down because I plan to release the app for free. I do recognise that an implementation that performs better in terms of CPU cycles and RAM usage (e.g. something compiled written in say C#?) might require more expensive hosting solutions than say a LAMP server so might actually end up being more expensive in terms of $/request.

I also want my implementation to be scalable in the rare case that a lot of people start using the app. Does the usage volume shift the performance/$ ratio towards a different implementation? I.e. if I have 1k request/day it might be cheaper to use PHP+MySQL, but 1M requests/day might make using something else cheaper?

To summarise, how would you implement a (fairly simple) remote database that would be accessed remotely using HTTP(S) in order to minimise hosting bills? What kind of hosting solution and what kind of platform/language?

UPDATE: per Karl's suggestion I tried: Ruby (language) + Sinatra (framework) + Heroku (app hosting) + Amazon S3 (static file hosting). To anyone reading this who might have the same dilemma I had, this setup is amazing: effortlessly scalable (to "infinity"), affordable, easy to use. Thanks Karl!

Can't comment on DB specifics yet because I haven't implemented that yet although for my simple query requirements, CouchDB and MongoDB seem like good choices and they are integrated with Heroku.

Answer 1

It comes down to a tradeoff between cost vs experience.

if you have the expertise, I would definitely look into some form of cloud based infrastructure, something like Google App Engine. Which cloud platform you go with depends on what experience you have with different languages (AppEngine only works with Python/Java for e.g). Generally though, scalable cloud based platforms have more "gotchas" and need more know-how, because they are specifically tuned for high-end scalability (and thus require knowledge of enterprise level concepts in some cases).

If you want to be up and running as quickly and simply as possible I would personally go for a CakePHP install. Setup the model data to represent the basic entities you are managing, then use CakePHP's wonderful convention-loving magic to expose CRUD updates on these models with ease!

Answer 2

The technology you use to implement the REST services will have a far less significant impact on performance and hosting costs than the way you use HTTP. Learning to take advantage of HTTP is far more than simply learning how to use GET, PUT, POST and DELETE.

Use whatever server side technology you already know and spend some quality time reading RFC2616. You'll save yourself a ton of time and money.

Answer 3

Have you considered using Sinatra and hosting it on [Heroku]? This is exactly what Sinatra excels at (REST services). And hosting with Heroku may be free, depending on the amount of data you need to store. Just keep all your supporting files (images, javascript, css) on S3. You'll be in the cloud and flying in no time.

This may not fit with your PHP desires, but honestly, it doesn't get any easier than Sinatra.

Answer 4

In your case its database server that's accessed on each request. so even if you have compiled language (say C# or java) it wont matter much (unless you are doing some data transformation or processing).

So DB server have to scale well. here your choice of language and DB should be well configured with host OS.

In short PHP+MySQL is good if you are sending/receiving JSON strings and storing/retrieving in DB with minimum data processing.

next app gets popular and if your app don't require frequent updates to existing data then you can move such data to very high scalable databases like MongoDB (JSON friendly).