루비가 얼랭에 빠진 날

http://thinkr.egloos.comsjoonk@gmail.com

제 6 회 루비세미나 (2008.6.28)

Concurrency-oriented Programming

3

How Erlang programs work?

• 많은 프로세스들로 구성– 운영체제 독립적인 경량 (light-weight) 프로세스– 유일한 식별자 (Pid)– 많은 프로세스를 동시 처리 (100,000 개 이상 )

• 프로세스들 간에 서로 메시지를 주고 받음– 비동기적 메시지 전달 메커니즘

• 프로세스는 서로 연결 (link) 될 수 있음– 연결된 프로세스가 죽으면 다른 프로세스가 통보받음– 수퍼바이저 / 워커 모델 구성

4

A Stateless Server Process-module(demo2).-compile(export_all).

run() -> Pid = spawn(fun echo/0), Pid ! {self(), hello, 42}, receive {Pid, reply, 42} ->

Pid ! stop end.

echo() -> receive {From, hello, Val} ->

From ! {self(), reply, Val},echo(); % loop!

stop ->io:format("Done!~n", []),ok

end.

P1

P2

{P1, hello, 42}

{P2, reply, 42}

Client

Server

stop

5

Benefits of COP

• 성능 (Performance)– 분산 병렬 처리– Multi-core Support

• 가용성 (Reliability)– 무정지 (fault-tolerent)– Hot code swapping

• 확장성 (Scalability)

6

generic_server

OTP gen_server 비헤비어

7

Apache vs. Yaws

* http://www.sics.se/~joe/apachevsyaws.html

REpresentational State Transfer

9

RESTful URL (Rails)

• GET /posts index• GET /posts/1 show• GET /posts/new new• GET /posts/1/edit edit• POST /posts create• PUT /posts/1 update• DELETE /posts/1 destroy

10

respond_to :wow!

# POST /posts # POST /posts.xml def create @post = Post.new(params[:post])

respond_to do |format| if @post.save flash[:notice] = 'Post was successfully created.' format.html { redirect_to(@post) } format.xml { render :xml => @post, :status => :created, :location => @post } else format.html { render :action => "new" } format.xml { render :xml => @post.errors, :status => :unprocessable_entity } end end end

11

GoogleTrends “ruby on rails”

1.0 1.2 2.0

resource 도입 from MVC to REST

12

The RADAR Architecture

* RESTful Application, Dumb-Ass Recipient (http://pragdave.pragprog.com/pragdave/2007/03/the_radar_archi.html)

Time to Relax…

14

CouchDB

문서 (document) 기반 데이터베이스 서버 .

Aaccessible via a RESTful JSON API Views (incremental map/reduce) Schema-Free Distributed, robust architecture Written in Erlang Apache Incubating (alpha 0.8 release)

15

SQL vs. CouchDB

SQL CouchDB

Predefined, explicit schema Dynamic, implicit schema

Uniform tables of data Collection of named documents with varying structure

Normalized. Objects spread across tables. Duplication reduced.

Denormalized. Docs usually self contained. Data often duplicated.

Must know schema to read/write a complete object Must know only document name

Dynamic queries of static schemas Static queries of dynamic schemas

* http://www.zefhemel.com/archives/2008/03/11/sittin-on-the-couchdb

16

Document = JSON Object

{

"_id":"discussion_tables",

"_rev":"D1C946B7",

"Subject":"I like Planktion",

"Author":"Rusty",

"PostedDate":"2006-08-15T17:30:12-04:00",

"Tags":["plankton", "baseball", "decisions"],

"Body":"I decided today that I don't like baseball. I like plankton."

}

17

Some CouchDB REST APIs• Dababase API

– GET /_all_dbs 모든 DB– PUT /database/ 새 DB 생성– DELETE /database/

• Document API– GET /database/doc_id– POST /database/ 또는 PUT /database/doc_id– PUT /database/doc_id (with ‘_rev’ property) – DELETE /database/dic_id?rev=xxx

• View API– GET /database/_view/view_name/func_name

18

Accessing CouchDB with Ruby

• 범용– ActiveResource– REST Client

• CouchDB 전용– CouchObject– Ruby-CouchDB– ActiveCouch– Couchrest

DEMO

20

Admin Interface

21

Ruby View

22

Extending AResclass CouchResource < ActiveResource::Base class << self def element_path(id, prefix_options = {}, query_options = nil) "#{prefix(prefix_options)}#{collection_name}/#{id}#{query_string(query_options)}"

def collection_path(prefix_options = {}, query_options = nil) "#{prefix(prefix_options)}#{collection_name}#{query_string(query_options)}"

def instantiate_collection(collection, prefix_options = {}) collection = collection.fetch("rows") if collection.kind_of? Hash

def instantiate_record(record, prefix_options = {}) record = record.fetch("value") if record.has_key? "value“ def find_view(view_name, func_name) find(:all, :from => "/#{element_name}/_view/#{view_name}/#{func_name}") end

23

Mywiki Resource

class Mywiki < CouchResource self.site = "http://localhost:5984" self.format = :json self.collection_name = 'mywiki' # used as a database name self.primary_key = '_id'end

24

Console Result

25

Finish!!