Rack::Cascade

Rack::Cascade tries an request on several apps, and returns the first response that is not 404 (or in a list of configurable status codes).

Ejemplo

[~/local/src/ruby/sinatra/rack/rack-cascade]$ cat cascade2.ru 
statuses = [200,404]
apps = [
  lambda {|env| 
    status = statuses.sample
    [status, {}, ["I'm the first app. Status = #{status}\n"]]
  }, 
  lambda {|env| 
    status = statuses.sample
    [status, {}, ["I'm the second app. Status = #{status}\n"]]
  }, 
  lambda {|env| 
    status = statuses.sample
    [status, {}, ["I'm the last app. Status = #{status}\n"]]
  } 
]
use Rack::ContentLength 
use Rack::ContentType 
run Rack::Cascade.new(apps)

[~/local/src/ruby/sinatra/rack/rack-cascade]$ rake client
curl -v 'http://localhost:9292'
* About to connect() to localhost port 9292 (#0)
*   Trying 127.0.0.1... connected
* Connected to localhost (127.0.0.1) port 9292 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8y zlib/1.2.5
> Host: localhost:9292
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Type: text/html
< Content-Length: 33
< Connection: keep-alive
< Server: thin 1.5.1 codename Straight Razor
< 
I'm the second app. Status = 200
* Connection #0 to host localhost left intact
* Closing connection #0

[~/local/src/ruby/sinatra/rack/rack-cascade]$ rake client
curl -v 'http://localhost:9292'
* About to connect() to localhost port 9292 (#0)
*   Trying 127.0.0.1... connected
* Connected to localhost (127.0.0.1) port 9292 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8y zlib/1.2.5
> Host: localhost:9292
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Type: text/html
< Content-Length: 31
< Connection: keep-alive
< Server: thin 1.5.1 codename Straight Razor
< 
I'm the last app. Status = 200
* Connection #0 to host localhost left intact
* Closing connection #0

[~/local/src/ruby/sinatra/rack/rack-cascade]$ rake client
curl -v 'http://localhost:9292'
* About to connect() to localhost port 9292 (#0)
*   Trying 127.0.0.1... connected
* Connected to localhost (127.0.0.1) port 9292 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8y zlib/1.2.5
> Host: localhost:9292
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Type: text/html
< Content-Length: 32
< Connection: keep-alive
< Server: thin 1.5.1 codename Straight Razor
< 
I'm the first app. Status = 200
* Connection #0 to host localhost left intact
* Closing connection #0]

Código del Constructor

        # File lib/rack/cascade.rb, line 11
11:     def initialize(apps, catch=404)
12:       @apps = []; @has_app = {}
13:       apps.each { |app| add app }
14: 
15:       @catch = {}
16:       [*catch].each { |status| @catch[status] = true }
17:     end

Código de call

        # File lib/rack/cascade.rb, line 19
19:     def call(env)
20:       result = NotFound
21: 
22:       @apps.each do |app|
23:         result = app.call(env)
24:         break unless @catch.include?(result[0].to_i)
25:       end
26: 
27:       result
28:     end