An introduction to Merb

1. Merb
An Introduction

2. Who am I?

3. History

4. Key Focus

5. Fast
(No code is faster than no code)

6. Memory Efficient

7. Modular
(All you need none you don’t)

8. As Simple As Possible

9. Features

10. Plugins as Gems

11. Rack Integration

12. File upload example using rack middleware
uploader = Proc.new do |env|
request = Merb::Request.new(env)
if request.path =~ //images/upload/
params = request.params
FileUtils.mv params[:file][:tempfile].path,
Merb.root / 'public' / 'uploads' / params[:file][:filename]
headers = {quot;Content-Typequot;=>quot;text/htmlquot;,
quot;Locationquot; => quot;/imagesquot;}
[302, headers, quot;You are being redirectedquot;]
else
[404, {}, quot;No Upload here, move alongquot;]
end
end
merb = Merb::Rack::Application.new
run Rack::Cascade.new([uploader, merb])

13. Router

14. Optional Path Segments
Matching
match(quot;/articles(/:year(/:month(/:day)))/:titlequot;).
to(:controller => quot;articlesquot;, :action => quot;showquot;).
name(:article)
Generating
/articles/Hello => { :title => “Hello” }
/articles/2008/07/Hello
=> { :year => “2008”, :month => “07”, :title => “Hello” }

15. Access to Request &
Params
match(quot;/secretquot;).defer_to do |request, params|
if request.session.authenticated?
params
end
end
http://www.slideshare.net/carllerche/merb-pluming-the-router-presentation

16. Controllers

17. class Posts < Application
provides :xml
def show
@post = Post.get(params[:id])
display @post
end
end

18. Background Processing

19. render_then_call do
send_notification
end
run_later do
send_notification
end

20. Exceptions

21. class Exceptions < Merb::Controller
# handle NotFound exceptions (404)
def not_found
render :format => :html
end
# handle NotAcceptable exceptions (406)
def not_acceptable
render :format => :html
end
end

22. Merb Slice

23. Application Server

24. merb -e produciton -d -c 4
Processes
• master
• spawner
• worker
Hot Deploy
kill HUP ‘master process id’

25. Questions?