layout	title	description	category	tags	image
post	Elixir MIX	Journey and Discovery of Elixir (journal)	Elixir		post_one.jpg

###newb cheats

iex
newb |> iex - Nothing to say here
newb |> iex.exs - iex script file
newb |> mix.exs - Elixir script file
newb |> mix deps.get
newb |> iex -S mix "use it Padawan"
newb |> AST quote do - discover code patterns
newb |> require Logger
newb |> Logger.debug("debug message: Make it meaningful")
newb |> alias :dbg, as: Dbg - get rid of the erlang ":"
newb |> :debug.tracer()
newb |> :dbg
newb |> import access functions/macros without fully-qualified name
newb |> require provides macros as a mechanism
phoenix
newb |> mix phoenix.new       # Creates Phoenix application
newb |> mix phoenix.routes    # Prints all routes
newb |> mix do deps.get, compile
newb |> mix phoenix.server    # Starts applications and their servers
environment
newb |> Webstorm Elixir Plugin - work horse
newb |> Vim Elixir - for remote and quick edits http://rustamserg.com
newb |> Google compute engine
newb |> Phoenix http://www.phoenixframework.org

##Style

Liquid architecture. It's like jazz - you improvise, you work together, you play off each other, you make something, they make something.
-- Frank Gehry

####A community driven style guide for Elixir

A curated list of amazingly awesome Elixir and Erlang libraries, resources and shiny things. Open community of shared knowledge ####A community driven list of Elixir and Erlang Libraries

Prelude

Elixir[erlang]

This README.md/Blog Entry is an exploratory expedition to understand this strange and seductive language called "Elixir."

I have been given a week to research and create a simple REST service.

This project is by no means a finished project. However, it is my best intentions to leave a path of artifacts. Artifacts of code links, ideas, and gotchas.

Conclusion

Time "flys" when you are "doing good." This first dive into Elixir has been a good dive. The Elixir language will require a "shift" in thinking for those indoctrinated into OOP.

Have I drunken the Elixir MIX? Not completely but I do see the definite merits of this language. Functional programming in my opinion is "Awesome." What more can I say!

I will come back and revisit this blog/README.md when I have learned and grokked more of Elixir. Maybe next time I will be a convert.

For those of you who are Elixir fans - Cheers my friends - Good stuff.

Goal

• Stand up a simple Elixir REST server
• Elixir is a Proxy to a REST service for CouchDB
• Included tid bits of advice and key knowledge points
• Learn Elixir
• Learn Phoenix
• Investigate JSON integration
• Integrate with Cloudant BigCouchDB (REST connect)
• CORS Cross-origin resource sharing (CORS) see web/security
• Discover, Correct, and learn more Elixir

Data Structure - Keep this unbelievably simple

Data Structure: {
                 user: "string",
                 status: string,
                 description: "string"
                 }

Abilities

1. Create - Add a Log entry [Post]
2. [] Read - A Log entry [Get]
3. [] Update - A Log entry [Post]
4. [] Delete - All: Purge all Journal Entries [Delete]

Wish LIst

1. [] Document Model to JSON coder/decoder
2. [] Integration module for CouchDB **** Nothing out there!
3. [] Data mapping library
4. [] Data validation Library
5. [] Larger community base of developers :)

###Inventory of Parts

• Erlang Erlang is a programming language used to build massively scalable soft real-time systems with requirements on high availability.
• Elixir Elixir is a dynamic, functional language designed for building scalable and maintainable applications.
• Cowboy Cowboy is a small, fast and modular HTTP server written in Erlang.
• Cowlib Cowlib is a support library for manipulating Web protocols.
• Phoenix Elixir Web Framework targeting full-featured, fault tolerant applications with realtime functionality
• Plugv A specification for composable modules in between web applications Connection adapters for different web servers in the Erlang VM
• Poison Poison is a new JSON library for Elixir focusing on wicked-fast
• Ranch Ranch is a socket acceptor pool for TCP protocols.
• HTTPoison HTTP Client module for Couch Connections

Phoenix Quick Start

1. mix phoenix.new elixir_mix ../elixir_mix
2. cd
3. mix do deps.get, compile
4. mix phoenix.server

###Directory

General

├── _build
├── config
├── deps
├── lib
├── priv
├── test
├── web

Web

├── channels
├── controllers
│   └── page_controller.ex
├── models
├── router.ex
├── templates
│   ├── layout
│   │   └── application.html.eex
│   └── page
│       ├── error.html.eex
│       ├── index.html.eex
│       └── not_found.html.eex
├── view.ex
└── views
    ├── error_view.ex
    ├── layout_view.ex
    └── page_view.ex

###The Router Parses incoming requests and dispatches to the correct controller/action, passing parameters as needed provides helpers to generate route paths or urls to resources

The router is the main hub of any Phoenix application.
It matches HTTP requests to controller actions, wires up realtime
channel handlers, and defines a series of pipeline transformations
for scoping middleware to sets of routes.

Added CORS Plug - See web/Security

Removed all Browser pipeline artifacts, turning Phoenix into a API server

defmodule ElixirMix.Router do
  use Phoenix.Router

  # REST Pipeline only
  pipeline :api do
    plug :accepts, ~w(json)
    plug CORSPlug
  end

  scope "/", ElixirMix do

    # API REST Service
    pipe_through :api # Use the default browser stack

    # REST Demo - curl is needed for this demo see README
    get    "/", CloudController, :index
    post   "/create", CloudController, :create
    get    "/read", CloudController, :read
    put    "/update", CloudController, :update
    delete "/delete", CloudController, :delete

  end

end

REST Service Example

newb |> mix phoenix.routes (Chose not to use this)

REST API Guidlines

####REST API Method Reference

CREATE POST

curl -X POST -H "Content-Type: application/json; charset=UTF-8" http://localhost:4000/create -d  '{"user":"Joe","status":"new","description":"Elixir demo log entry"}'

result = {"ok":true,"id":"ac600e473be3bab790d6ea66f0c04564"}

READ GET

curl http://localhost:4000/read?id=1

result = {"user":"joe","status":"new","ok":"read","description":"Simple CRUD Read from Elixir"}

UPDATE PUT

curl -X PUT -H "Content-Type: application/json" http://localhost:4000/update  -d  '{"id":"9"}'

result = {"ok":"update - simulation"}

DELETE DELETE

curl -X DELETE http://localhost:4000/delete?id=1

result = {"ok":"delete - simulation"}

[] Note: HTTPoison example - will refactor

  # Using HttPoision Mirror
  def mirror(conn, _params) do

      Logger.debug "mirror my request"
      url = "http://127.0.0.1:4000/read?id=1"
      Logger.debug url
      case HTTPoison.get(url) do
        {:ok, %HTTPoison.Response{status_code: 200, body: body}} ->
          json conn, body
        {:ok, %HTTPoison.Response{status_code: 404}} ->
          IO.puts "Not found :("
        {:error, %HTTPoison.Error{reason: reason}} ->
          IO.inspect reason
      end

  end

Define a view based on named controller

NA

Define a template web/templates/

NA

###The Endpoint NA

###Controllers

Provide functions called actions to handle requests Actions

For this demo the CREATE action has been integrated with CouchDB all others return mock JSON data

[] Note: HTTPoison example - will refactor

  # Using HttPoision Mirror
  def mirror(conn, _params) do

      Logger.debug "mirror my request"
      url = "http://127.0.0.1:4000/read?id=1"
      Logger.debug url
      case HTTPoison.get(url) do
        {:ok, %HTTPoison.Response{status_code: 200, body: body}} ->
          json conn, body
        {:ok, %HTTPoison.Response{status_code: 404}} ->
          IO.puts "Not found :("
        {:error, %HTTPoison.Error{reason: reason}} ->
          IO.inspect reason
      end

  end

defmodule ElixirMix.CloudController do
  use Phoenix.Controller

  require Logger

  plug :action

  # INDEX Default service check - used for status of service only
  def index(conn, _params) do

    conn |> put_resp_content_type "application/json"
    json conn, %{ok: "index - simulation"}

  end

  # CREATE
  def create(conn, _params) do

    # Submit create request and get reposonse from Cloudant
    response = CouchDB.create _params["user"], _params["status"], _params["description"]
    completedok = response |> elem 0

    # Prepare response to client
    conn |> put_resp_content_type "application/json"

    # Completed return Cloudant ID
    # Todo: Need to refactor this portion see above HTTPoison Example -
    # Todo: Get rid of the If else
    if completedok do
      map = response |> elem 1
      id = map["id"]
      json conn, %{ok: true, id: id}
    else
      json conn, %{ok: false}
    end

  end

  # READ curl http://localhost:4000/read?id=1
  def read(conn, _parms) do

    Logger.debug "GET read"
    conn |> put_resp_content_type "application/json"
    json conn, %{ok: "read", user: "joe", status: "new", description: "Simple CRUD Read from Elixir"}

  end

  # UPDATE curl -X PUT -H "Content-Type: application/json" http://localhost:4000/update  -d  '{"id":"9"}'
  def update(conn, _params) do

    Logger.debug "PUT update"
    conn |> put_resp_content_type "application/json"
    json conn, %{ok: "update - simulation"}

  end

  # DELETE curl -X DELETE http://localhost:4000/delete?id=1
  def delete(conn, _params) do

    Logger.debug "DELETE delete"
    conn |> put_resp_content_type "application/json"
    json conn, %{ok: "delete - simulation"}

  end

end

###Views NA

###Templates NA

###Channels NA

###Sockets NA

###Topics NA

Cloudant aka BigCouch Integration

Please modify this module for given credentials

web/couchdb

defmodule CouchServer do

  # Server credentials and info
  defstruct schema: "https://",
            port: "4000",
            userName: "super",
            password: "man",
            path:  "/",
            host: "@bizrez.cloudant.com",
            hostNoSecurity: "bizrez.cloudant.com",
            header: ["Accept": "application/json","Content-type": "application/json;charset=utf-8"],
            query: ""
end

Other

Time Test

time curl -X POST -H "Content-Type: application/json; charset=UTF-8" "http://localhost:4000/create?[1-1000]" -d  '{"user":"Joe","status":"new","description":"Elixir demo log entry"}'

or

run a script

time ./timetest_get.sh

Installation and Run

1. git clone https://github.com/mallond/elixir-mix.git
2. cd elixir-mix
3. mix deps.get
4. mix Phoenix.server

Do the curl commands mentioned above [curl CREATE method may need credentials]