Merb 2.0
The long march into the future

Core Merb Principles

In Depth

Performance

Requests Per Second

Thin Mongrel

run proc do |env|
[
200,
{\"Content-Type\" => \"text/html\"},
\"Hello from rack\"
]
end

class QuickApp
def call(env)
[
200,
{\"Content-Type\" => \"text/html\"},
\"Hello from rack\"
]
end
end
run QuickApp.new

class QuickApp
def call(env)
[
200,
{\"Content-Type\" => \"text/html\"},
\"Hello from rack\"
]
end
end
run QuickApp.new

Thin Mongrel

match(\"/router\").defer_to do |req, res|
[
200,
{\"Content-Type\" => \"text/html\"},
\"Hello\"
]
end

Thin Mongrel

class MyApp < Application
def string
\"String\"
end
end

class MyApp < Application
def string
\"String\"
end
end

Thin Mongrel

class MyApp < Application
def index
render
end
def string
\"String\"
end
end

class MyApp < Application
def index
render
end
def string
\"String\"
end
end

Close to the metal as possible

Close to the metal as you want

Performance Testing

KCacheGrind

use Merb::Rack::Profile

profile/url/callgrind.out.time

5% or greater

10% or greater

10% or greater
Merb::RenderMixin::_get_layout
10.05 %

Mini-demo

Concurrency

20
16
12
8
4
0
1 2 4 8 16 32
Ideal concurrency curve

1 request in 16ms (16ms/req)

2 requests in 16ms (8ms/req)

4 requests in 16ms (4ms/req)

8 requests in 16ms (2ms/req)

16 requests in 16ms (1ms/req)

32 requests in 16ms (2req/ms)

20
16
12
8
4
0
1 2 4 8 16 32
Ideal concurrency curve

Chart 10
15.00
11.25
7.50
3.75
0
1 2 4 8 16 32
Merb MRI concurrency curve

Chart 12
15.00
11.25
7.50
3.75
0
1 2 4 8 16 32
Merb JRuby (Mongrel) concurrency curve

Chart 13
15.00
11.25
7.50
3.75
0
1 2 4 8 16 32 64 128 256
Merb Glassfish concurrency curve

Chart 13
15.00
11.25
7.50
3.75
0
1 2 4 8 16 32 64 128 256
Not ideal

Chart 13
15.00
11.25
7.50
3.75
0
1 2 4 8 16 32 64 128 256
Not ideal

Chart 13
15.00
11.25
7.50
3.75
0
1 2 4 8 16 32 64 128 256
Not ideal (but it works)

Chart 13
15.00
11.25
7.50
3.75
0
1 2 4 8 16 32 64 128 256
Not ideal (but it works)

Threadsafety

Merb::Config[:use_mutex]

class User
cattr_accessor :current
end
class Foo < Merb::Controller
before do
User.current = session.user
end
end

class User
cattr_accessor :current
end
class Foo < FAIL
Merb::Controller
before do
User.current = session.user
end
end

Shared state hurts puppies

Solutions

Thread-local

class User
def self.current=(user)
Thread.current[:user] = user
end
def self.current
Thread.current[:user]
end
end
class Foo < Merb::Controller
before do
User.current = session.user
end
end

Using a Hash across threads

Hash {:x => 5}

Hash {:x => 5}
Thread 1 Thread 2

Hash {:x => 5}
Thread 1 Thread 2

Hash {:x => 5}
Thread 1 Thread 2
Read x

Hash {:x => 5}
Thread 1 Thread 2
Read x Write x=”1”

Hash {:x => 5}
Thread 1 Thread 2
Read x Write x=”1”
clear x

Hash {:x => 5}
Thread 1 Thread 2
Read x Write x=”1”
clear x
is there an x?

Hash {:x => 5}
Thread 1 Thread 2
Read x Write x=”1”
clear x
is there an x?
no? return nil x=1

Mutex

Hash {:x => 5}

Hash {:x => 5}
Thread 1 Thread 2

Hash {:x => 5}
Thread 1 Thread 2
Read x
is there an x?
yes? return 5

Hash {:x => 5}
Thread 1 Thread 2
Read x Write x=”1”
clear x
is there an x?
yes? return 5 x=1

Hash {:x => 5}

Hash {:x => 5}
Thread 1 Thread 2

Hash {:x => 5}
Thread 1 Thread 2
Write x=”1”
clear x
x=1

Hash {:x => 5}
Thread 1 Thread 2
Read x Write x=”1”
clear x
is there an x?
yes? return 1 x=1

Mutexes make non-atomic
operations atomic

Modularity

merb_gems_version = \"1.0.4\"
dm_gems_version = \"0.9.7\"
dependency \"merb-action-args\", merb_gems_version
dependency \"merb-assets\", merb_gems_version
dependency \"merb-cache\", merb_gems_version
dependency \"merb-helpers\", merb_gems_version
dependency \"merb-mailer\", merb_gems_version
dependency \"merb-slices\", merb_gems_version
dependency \"merb-auth-core\", merb_gems_version
dependency \"merb-auth-more\", merb_gems_version
dependency \"merb-auth-slice-password\", merb_gems_version
dependency \"merb-param-protection\", merb_gems_version
dependency \"merb-exceptions\", merb_gems_version
dependency \"dm-core\", dm_gems_version
dependency \"dm-aggregates\", dm_gems_version
dependency \"dm-migrations\", dm_gems_version
dependency \"dm-timestamps\", dm_gems_version
dependency \"dm-types\", dm_gems_version
dependency \"dm-validations\", dm_gems_version

merb_gems_version = \"1.0.4\"
dm_gems_version = \"0.9.7\"
dependency \"merb-action-args\", merb_gems_version
dependency \"merb-assets\", merb_gems_version
dependency \"merb-cache\", merb_gems_version
dependency \"merb-helpers\", merb_gems_version
dependency \"merb-mailer\", merb_gems_version
dependency \"merb-slices\", merb_gems_version
dependency \"merb-auth-core\", merb_gems_version
dependency \"merb-auth-more\", merb_gems_version
dependency \"merb-auth-slice-password\", merb_gems_version
dependency \"merb-param-protection\", merb_gems_version
dependency \"merb-exceptions\", merb_gems_version
dependency \"dm-core\", dm_gems_version
dependency \"dm-aggregates\", dm_gems_version
dependency \"dm-migrations\", dm_gems_version
dependency \"dm-timestamps\", dm_gems_version
dependency \"dm-types\", dm_gems_version
dependency \"dm-validations\", dm_gems_version

merb_gems_version = \"1.0.4\"
dm_gems_version = \"0.9.7\"
dependency \"merb-action-args\", merb_gems_version
dependency \"merb-assets\", merb_gems_version
dependency \"merb-cache\", merb_gems_version
dependency \"merb-helpers\", merb_gems_version
dependency \"merb-mailer\", merb_gems_version
dependency \"merb-slices\", merb_gems_version
dependency \"merb-auth-core\", merb_gems_version
dependency \"merb-auth-more\", merb_gems_version
dependency \"merb-auth-slice-password\", merb_gems_version
dependency \"merb-param-protection\", merb_gems_version
dependency \"merb-exceptions\", merb_gems_version
dependency \"dm-core\", dm_gems_version
dependency \"dm-aggregates\", dm_gems_version
dependency \"dm-migrations\", dm_gems_version
dependency \"dm-timestamps\", dm_gems_version
dependency \"dm-types\", dm_gems_version
dependency \"dm-validations\", dm_gems_version

merb_gems_version = \"1.0.4\"
dm_gems_version = \"0.9.7\"
dependency \"merb-action-args\", merb_gems_version
dependency \"merb-assets\", merb_gems_version
dependency \"merb-cache\", merb_gems_version
dependency \"merb-helpers\", merb_gems_version
dependency \"merb-mailer\", merb_gems_version
dependency
dependency
\"merb-slices\", merb_gems_version
1 .1.4
\"merb-auth-core\", merb_gems_version
dependency
uby
\"merb-auth-more\", merb_gems_version
dependency
dependency J R
\"merb-auth-slice-password\", merb_gems_version
\"merb-param-protection\", merb_gems_version
dependency \"merb-exceptions\", merb_gems_version
dependency \"dm-core\", dm_gems_version
dependency \"dm-aggregates\", dm_gems_version
dependency \"dm-migrations\", dm_gems_version
dependency \"dm-timestamps\", dm_gems_version
dependency \"dm-types\", dm_gems_version
dependency \"dm-validations\", dm_gems_version

merb_gems_version = \"1.0.4\"
dm_gems_version = \"0.9.7\"
dependency \"merb-action-args\", merb_gems_version
dependency \"merb-assets\", merb_gems_version
dependency \"merb-cache\", merb_gems_version
dependency \"merb-helpers\", merb_gems_version
dependency \"merb-mailer\", merb_gems_version
dependency \"merb-slices\", merb_gems_version
dependency \"merb-auth-core\", merb_gems_version
dependency \"merb-auth-more\", merb_gems_version
dependency \"merb-auth-slice-password\", merb_gems_version
dependency \"merb-param-protection\", merb_gems_version
dependency \"merb-exceptions\", merb_gems_version
dependency \"dm-core\", dm_gems_version
dependency \"dm-aggregates\", dm_gems_version
dependency \"dm-migrations\", dm_gems_version
dependency \"dm-timestamps\", dm_gems_version
dependency \"dm-types\", dm_gems_version
dependency \"dm-validations\", dm_gems_version

merb_gems_version = \"1.0.4\"
dm_gems_version = \"0.9.7\"
dependency \"merb-action-args\", merb_gems_version
dependency \"merb-assets\", merb_gems_version
dependency \"merb-cache\", merb_gems_version
dependency \"merb-helpers\", merb_gems_version
dependency \"merb-mailer\", merb_gems_version
dependency
.5+
\"merb-slices\", merb_gems_version
dependency
1 .1
\"merb-auth-core\", merb_gems_version
dependency
dependency by
\"merb-auth-more\", merb_gems_version
Ru
\"merb-auth-slice-password\", merb_gems_version
dependency J
\"merb-param-protection\", merb_gems_version
dependency \"merb-exceptions\", merb_gems_version
dependency \"dm-core\", dm_gems_version
dependency \"dm-aggregates\", dm_gems_version
dependency \"dm-migrations\", dm_gems_version
dependency \"dm-timestamps\", dm_gems_version
dependency \"dm-types\", dm_gems_version
dependency \"dm-validations\", dm_gems_version

@overridable

# This is a stub method so plugins can
# implement param filtering if they want.
#
# ==== Parameters
# params<Hash{Symbol => String}>::
# A list of params
#
# ==== Returns
# Hash{Symbol => String}::
# A new list of params, filtered as desired
#
# :api: plugin
# @overridable
def self._filter_params(params)
params
end

class Articles < Application
params_accessible :article =>
[:title, :body]
end

class Articles < Application
params_accessible :article =>
[:title, :body]
end

class Articles < Application
def self._filter_params(params)
# deep_clone
ret =
Marshal.load(Marshal.dump(params))
ret[:post].reject! do |k,v|
!k.in?(:title, :body)
end
end
end

class Articles < Application
def self._filter_params(params)
# deep_clone
ret =
Marshal.load(Marshal.dump(params))
ret[:post].reject! do |k,v|
!k.in?(:title, :body)
end
end
end

# :api: public
# @overridable
def _template_location(ctx, type, ctrlr)
_conditionally_append_extension(
ctrlr ?
\"#{ctrlr}/#{ctx}\" :
\"#{ctx}\", type)
end

class Articles < Application
def self._template_location(
ctx, type, ctrlr)
\"#{ctrlr}.#{ctx}.#{type}\"
end
end

class Articles < Application
def self._template_location(
ctx, type, ctrlr)
\"#{ctrlr}.#{ctx}.#{type}\"
end
end

class Articles < Application
def self._template_location(
t”
ay
ctx, type, ctrlr)
l ou
r= “
ro lle
nt
\"#{ctrlr}.#{ctx}.#{type}\"
co
end
end

class Articles < Application
self.template_roots = [
[
Merb.root / \"app\" / \"views\",
:_template_location
],
[
Merb.root / \"my_views\",
:_my_template_location
]
]
end

>> MerbAuthSlicePassword::Sessions.template_roots
#=> [[\"/Users/wycats/Code/wycats/test/awesome/app/
views\", :_template_location], [\"/Library/Ruby/Gems/1.8/gems/
merb-auth-slice-password-1.0.4/app/
views\", :_slice_template_location], [\"/Users/wycats/Code/wycats/
test/awesome/slices/merb-auth-slice-password/app/
views\", :_slice_template_location]]

>> MerbAuthSlicePassword::Sessions.template_roots
#=> [[\"/Users/wycats/Code/wycats/test/awesome/app/
views\", :_template_location], [\"/Library/Ruby/Gems/1.8/gems/
merb-auth-slice-password-1.0.4/app/
views\", :_slice_template_location], [\"/Users/wycats/Code/wycats/
test/awesome/slices/merb-auth-slice-password/app/
views\", :_slice_template_location]]

>> MerbAuthSlicePassword::Sessions.template_roots
#=> [[\"/Users/wycats/Code/wycats/test/awesome/app/
views\", :_template_location], [\"/Library/Ruby/Gems/1.8/gems/
merb-auth-slice-password-1.0.4/app/
views\", :_slice_template_location], [\"/Users/wycats/Code/wycats/
test/awesome/slices/merb-auth-slice-password/app/
views\", :_slice_template_location]]

>> MerbAuthSlicePassword::Sessions.template_roots
#=> [[\"/Users/wycats/Code/wycats/test/awesome/app/
views\", :_template_location], [\"/Library/Ruby/Gems/1.8/gems/
merb-auth-slice-password-1.0.4/app/
views\", :_slice_template_location], [\"/Users/wycats/Code/wycats/
test/awesome/slices/merb-auth-slice-password/app/
views\", :_slice_template_location]]

>> MerbAuthSlicePassword::Sessions.template_roots
#=> [[\"/Users/wycats/Code/wycats/test/awesome/app/
views\", :_template_location], [\"/Library/Ruby/Gems/1.8/gems/
merb-auth-slice-password-1.0.4/app/
views\", :_slice_template_location], [\"/Users/wycats/Code/wycats/
test/awesome/slices/merb-auth-slice-password/app/
views\", :_slice_template_location]]

>> MerbAuthSlicePassword::Sessions.template_roots
#=> [[\"/Users/wycats/Code/wycats/test/awesome/app/
views\", :_template_location], [\"/Library/Ruby/Gems/1.8/gems/
merb-auth-slice-password-1.0.4/app/
views\", :_slice_template_location], [\"/Users/wycats/Code/wycats/
test/awesome/slices/merb-auth-slice-password/app/
views\", :_slice_template_location]]

>> MerbAuthSlicePassword::Sessions.template_roots
#=> [[\"/Users/wycats/Code/wycats/test/awesome/app/
views\", :_template_location], [\"/Library/Ruby/Gems/1.8/gems/
merb-auth-slice-password-1.0.4/app/
views\", :_slice_template_location], [\"/Users/wycats/Code/wycats/
test/awesome/slices/merb-auth-slice-password/app/
views\", :_slice_template_location]]

def _slice_template_location(ctx, type, ctrlr)
if ctrlr && ctrlr.include?('/')
# skip first segment if given (which is the module name)
segments = ctrlr.split('/')
\"#{segments[1,segments.length-1].join('/')}/#{ctx}.#{type}\"
else
# default template location logic
_template_location(ctx, type, ctrlr)
end
end

Templates

def load_template_io(path)
file = Dir[
\"#{path}.{#{template_extensions.join(',')}}\"
].first
File.open(file, \"r\") if file
end

def load_template_io(path)
templates = {
Merb.root / \"app\" / \"views\" / \"template_io\" /
\"index.html.erb\" => \"Hello world\",
Merb.root / \"app\" / \"views\" / \"template_io\" /
\"two.html.erb\" => \"Two\"
}
if templates[path + \".erb\"]
VirtualFile.new(templates[path + \".erb\"], path + \".erb\")
else
file = Dir[
\"#{path}.{#{template_extensions.join(',')}}\"
].first
File.open(file, \"r\") if file
end
end

Merb::Router.prepare {default_routes}
class TemplateIo < Merb::Controller
def index
render
end
def two
render
end
end

Quick demo

Good Ruby citizen

Rubygems

Rubygems :(

Rubygems -- but getting :)

Working with community ==
helping the community

Rack

Rack middleware

Where is this going?

Apps as a first-class concept

module MyApp
class TemplateIo < Application
def index
render
end
def two
render
end
end
end

module MyApp
class TemplateIo < Application
def index
render
end
def two
render
end
end
end

module MyApp
class TemplateIo < Application
def index
render MyApp::Application
end
def two
render
end
end
end

module MyApp
extend Merb::App
mount ::Blog, :at => \"/blog\"
Config[:framework] = flat
end

Blog::Config[:log_delimiter] = \"BLOG: \"

Admin Application/Framework

CMS Application

DB Admin Application

Slices on Steroids

Resources as a
first-class concept

module MyApp
class Resource < Merb::Resource
def list(klass)
klass.all
end
def get(klass, ids)
klass.get(ids)
end
def authorized?(namespace, *args)
user == \"wycats\"
end
def user
request.session.user
end
end
end

Why?

DRYing up common idioms

Increasing flexibility
(where needed)

Core principle:
Simple cases can’t get harder

Further improve merb server

Short term

Long term

Dynamic worker pools

Remove need for nginx

Self-managing cluster

Additional modules

i18n

l10n

Feed syndication

Flat pages

More powerful router

Router directly to a view

even better resource()

Framework for OSS Apps

Authentication

User Management

Authorization

Note:
Communication primitives

Tailored stacks

Designers

Web shops