Building Web-API without Rails, Registration or SMS

About me
Andriy Savchenko /ptico
CTO Aejis
andriy@aejis.eu

W A R N I N G
THIS TALK
CONTAINS
LOTS 
OF CODE
THIS IS YOUR LAST CHANCE TO LEAVE AUDITORY

• Low latency
• Dependency hell
• MVC is only suitable for simple CRUD
• ActiveSupport

• grape
• sinatra
• rum
• nyny

run ->(env) {
[
200, # <= Response code
{'Content-Type' => 'application/json'}, # <= Headers
[ '{"a": 1}' ] # <= Body
]
}

require 'json'
run ->(env) {
[
200,
{'Content-Type' => 'application/json'},
[ JSON.dump({ a: 1 }) ] # <= Almost API ;)
]
}

class Responder
def response_code
200
end
def headers
{'Content-Type' => 'application/json'}
end
def body
[ JSON.dump({ a: 1 }) ]
end
end

class Responder
def response_code
@code
end
def headers
@headers
end
def body
[ JSON.dump(@body) ]
end
end

class Example < Responder
def initialize(env)
@code = 200
@headers = {'Content-Type' => 'application/json'}
@body = { a: 1 }
end
end

class ReadUsers < Responder
def initialize(env)
@code = 200
@headers = {'Content-Type' => 'application/json'}
@body = DB[:users].all
end
end

run ->(env) {
result = ReadUsers.new(env)
[result.response_code, result.headers, result.body]
}

result = ReadUsers.new(env)
r = Nginx::Request.new
result.headers.each_pair { |k, v| r.headers_out[k] = v }
Nginx.rputs result.body[0]
Nginx.return result.response_code

Good API
• Proper status codes
• Compatibility (?suppress_response_code=true)
• Metadata

class Responder
class << self
def call(env)
req = ::Rack::Request.new(env)
instance = new(req)
instance.call
instance.to_rack_array
end
end
attr_reader :request, :params, :headers
def initialize(req)
@request = req
@params = req.params
@headers = default_response_headers
end
def call; end
def to_rack_array
[http_response_code, http_response_headers, http_response_body]
end
end

class Responder
def response_code
@response_code || default_response_code
end
private
def default_response_code
200
end
def http_response_code
params['suppress_response_codes'] ? 200 : response_code
end
end

class Responder
def default_response_headers
{ 'Content-Type' => 'application/json' }.dup
end
def http_response_headers
@headers
end
end

class Responder
def body
@body
end
private
def http_response_body
[ JSON.dump(body) ]
end
end

class ReadUsers < Responder
def call
@body = DB[:users].all
end
end

class Read < Responder
def call
@body = fetch
end
end

class ReadUsers < Read
def fetch
DB[:users].all
end
end

class Write < Responder
def call
@body = valid_params? ? success : failure
end
private
def success; end
def failure; end
def valid_params?
true
end
end

class CreateUser < Write
def default_response_code
201
end
def valid_params?
params['login'] && params['email']
end
def success
DB[:users].insert(params)
end
def failure
@response_code = 400
{ error: 'Invalid params' }
end
end

class Responder
def body
{
code: http_response_code,
result: @body,
meta: meta
}
end
def meta
{
server_time: Time.now.to_i
}
end
end

{
"code": 200,
"result": [
{
"id": 1,
"name": "Andriy Savchenko",
"email": "andriy@aejis.eu",
"company": "Aejis",
"hiring": true
}
],
"meta": {
"server_time": 1447939835
}
}

Routers
• Rack::Builder
• http_router (gh:joshbuddy/http_router)
• lotus-router (gh:lotus/router)
• signpost (gh:Ptico/signpost)
• journey (dead)

Faster
$ ruby -v
ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin15]
$ puma -e production
$ ab -n 10000 -c 100 http://0.0.0.0:9292/users/
|======================|====Rails-API====|=====Sinatra=====|=====Rack API====|
|Time taken for tests: | 13.262 seconds | 6.858 seconds | 3.665 seconds |
|Complete requests: | 10000 | 10000 | 10000 |
|Failed requests: | 0 | 0 | 0 |
|Requests per second: | 754.03 [#/sec] | 1458.20 [#/sec] | 2728.28 [#/sec] |
|Time per request: | 132.620 [ms] | 68.578 [ms] | 36.653 [ms] |
|Time per request (c): | 1.326 [ms] | 0.686 [ms] | 0.367 [ms] |
|Transfer rate: | 301.91 [KB/sec] | 262.02 [KB/sec] | 402.31 [KB/sec] |
|============================================================================|

Faster
• 4x faster then rails-api & 2x then sinatra
• Ready for further improvements

Magic-less
• Base responder takes ≈ 65LOC
• The only dependency is Rack (optional)

Maintainable
• Stable object interface
• Each responder can have its own ﬁle structure
• SOLID
• Test-friendly

Questions?
Credits and attributions:
• Title illustration by Max Bohdanowski
• Lobster Two font by Pablo Impallari & Igino Marini (OFL)
• Font Awesome by Dave Gandy - http://fontawesome.io (OFL)
• https://www.ﬂickr.com/photos/mattsh/14194586111/ (CC BY-NC-SA 2.0)
Andriy Savchenko /ptico
andriy@aejis.eu

Building Web-API without Rails, Registration or SMS

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