What are scenarios in which one would use Sinatra or Merb?

Question

I am learning Rails and have very little idea about Sinatra & Merb. I was wondering are the situations where you would use Merb/Sinatra.

Thanks for your feedback!

Answer 1

Sinatra is a much smaller, lighter weight framework than Rails. It is used if you want to get something up running quickly that just dispatches off of a few URLs and returns some simple content. Take a look at the Sinatra home page; that is all you need to get a "Hello, World" up and running, while in Rails you would need to generate a whole project structure, set up a controller and a view, set up routing, and so on (I haven't written a Rails app in a while, so I don't know exactly how many steps "Hello, World" is, but its certainly more than Sinatra). Sinatra also has far fewer dependencies than Rails, so it's easier to install and run.

We are using Sinatra as a quick test web server for some web client libraries that we're writing now. The fact that we can write one single file and include all of our logic in that one file, and have very few dependencies, means it's a lot easier to work with and run our tests than if you had a Rails app.

Merb is being merged into Rails, so pretty soon there shouldn't really be any reason to use one over the other. It was originally designed to be a bit lighter weight and more decoupled than Rails; Rails had more built in assumptions that you would use ActiveRecord. But as they are merging the two, they are decoupling Rails in similar ways, so if you're already learning Rails, then it's probably worth it to just stick with that and follow the developments as they come.

Answer 2

I can't speak much for Merb, but Sinatra is highly effective for small or lightweight solutions. If you aren't working with a whole lot of code, or don't need a huge website, you can code a very effective site with Sinatra either as fast, or twice as fast as on Rails (in my own opinion).

Sinatra is also excellent for fragmentary pieces of an application, for instance the front-end to a statistics package. Or something like ErrCount, which is just a really simple hit counter.

So think about light, fast, and highly simplistic web applications (though complexity is your choice) when using Sinatra.

Answer 3

The way things are going, it's going to be a moot question soon.

As mentioned already, Merb 2.0 and Rails 3.0 are going to be the same thing. The newly-combined Merb and Rails core teams are already at work on achieving that. I don't know if they're still planning on a release (probably a beta) by RailsConf in May, but it's definitely happening this year.

If you're dead set on using an ORM other than ActiveRecord, for example, you might start with Merb now and update when 2.0 (Rails 3.0) ships. Right now, Merb is generally accepted to provide a better framework for varying one's components than Rails.

Sinatra looks like a brilliant solution for a web app that has low interface complexity and somewhat lower model-level code than would be normal for Merb/Rails. Implementing straightforward RESTful APIs would be one great use. I'm less convinced about its value when any quantity of HTML is involved, even less so when templating gets involved.

Again, with Rails (and hence Merb soon) now sitting on top of Rack, there's no reason not to include baby Sinatra apps into the solution: they can live together. There's a blog post that discusses that very concept