# Mounting Applications

Padrino applications are all automatically mountable into other Padrino
projects. This means that a given Padrino project directory can easily mount
multiple applications. This allows for better organization of complex
applications, re-usable applications that can be applied (i.e admin, auth, blog)
and even more flexibility.

You can think of mountable applications as a "full-featured"
[Merb](https://github.com/merb/merb "Merb") slice or Rails engine. Instead of a
separate construct, any application can simply be packaged and mounted into
another project.

--------------------------------------------------------------------------------

## Mounting Syntax

Padrino stores application mounting information by default within
`config/apps.rb`. This file is intended to keep all information regarding what
applications are mounted to which URI's. An `apps.rb` file has the following
structure:

```ruby
Padrino.mount('blog').to('/blog')
Padrino.mount('website').to('/website')
Padrino.mount('app').to('/')
```

This would mount three applications onto the Padrino project, one served from
the '/blog' uri namespace one with '/website' uri namespace and the other served
from the '/' uri namespace.

--------------------------------------------------------------------------------

## Advanced Mounting Support

In addition to the basic mounting capabilities afforded by Padrino for each
application within a project, the
[Padrino Router](http://github.com/padrino/padrino-framework/blob/master/padrino-core/lib/padrino-core/router.rb)
also allows for more advanced mounting conditions.

The `Padrino::Router` is an enhanced version of
[Rack UrlMap](http://github.com/rack/rack/blob/master/lib/rack/urlmap.rb) which
extends the ability to mount applications to a specified path, or specify host
and subdomains to match to an application. For example, you could put the
following in your `config/apps.rb` file:

```ruby
# Adds support for matching an app to a host string or pattern
Padrino.mount('Blog').to('/').host('blog.example.org')
Padrino.mount('Admin').host('admin.example.org')
Padrino.mount('WebSite').host(/.*\.?example.org/)
Padrino.mount('Foo').to('/foo').host('bar.example.org')
```

This will configure each application to match to the given host pattern
simplifying routing considerably.