Exos
====
Exos is a simple Port Wrapper : a GenServer which forwards cast and call to a
linked Port. Requests and responses are converted using binary erlang term
external representation.
You can use it to create a GenServer for Python, Clojure, NodeJS with :
- [clojure-erlastic](http://github.com/awetzel/clojure-erlastic)
- [python-erlastic](http://github.com/awetzel/python-erlastic)
- [node-erlastic](http://github.com/awetzel/node_erlastic)
## Launching a Clojure/Python/NodeJS GenServer and use it in Elixir ##
```elixir
defmodule Account do
def cmd do
case Application.get_env(:account_impl) do
:python-> "venv/bin/python -u account.py"
:node-> "node account.js"
:clojure-> "java -cp 'target/*' clojure.main account.clj"
end
end
def start_link(ini), do: GenServer.start_link(Exos.Proc,{cmd,ini,cd: "#{:code.priv_dir(:myproj)}/account"},name: __MODULE__)
def add(v), do: GenServer.cast(__MODULE__,{:add,v})
def rem(v), do: GenServer.cast(__MODULE__,{:rem,v})
def get, do: GenServer.call(__MODULE__,:get,:infinity)
end
defmodule MyProj.App do
use Application
def start(_,_), do: MyProj.App.Sup.start_link
defmodule Sup do
use Supervisor
def start_link, do: Supervisor.start_link(__MODULE__,[])
def init([]), do: supervise([
worker(Account,0)
], strategy: :one_for_one)
end
end
```
> vim mix.exs
```elixir
def application do
[mod: { MyProj.App, [] }]
end
```
Finally just implement your account server in any language as describe below,
and use it as a standard GenServer.
> iex -S mix
```elixir
Account.add(5)
Account.rem(1)
4 == Account.get
```
## Account Server Implementation in clojure ##
```bash
mix new myproj
cd myproj ; mkdir -p priv/account; cd priv/account
vim project.clj
```
```clojure
(defproject account "0.0.1"
:dependencies [[clojure-erlastic "0.2.3"]
[org.clojure/core.match "0.2.1"]])
```
```bash
lein uberjar
vim account.clj
```
```clojure
(require '[clojure-erlastic.core :refer [run-server]])
(use '[clojure.core.match :only (match)])
(run-server
(fn [term count] (match term
[:add n] [:noreply (+ count n)]
[:rem n] [:noreply (- count n)]
:get [:reply count count])))
```
## Account Server Implementation in Python >3.4 ##
```bash
mix new myproj
cd myproj ; mkdir -p priv/account; cd priv/account
echo "git://github.com/awetzel/python-erlastic.git#egg=erlastic" > requirements.txt
pyvenv venv
./venv/bin/pip install -r requirements.txt
vim account.py
```
```python
mailbox,port = port_connection()
account = next(port) #first msg is initial state
for req in mailbox:
if req == "get": port.send(account)
else:
(op,amount) = req
account = (account+amount) if op=="add" else (account-amount)
```
## Account Server Implementation in NodeJS ##
```bash
mix new myproj
cd myproj ; mkdir -p priv/account; cd priv/account
npm init
npm install node_erlastic --save
vim account.js
```
```javascript
require('node_erlastic').server(function(term,from,current_amount,done){
if (term == "get") return done("reply",current_amount);
if (term[0] == "add") return done("noreply",current_amount+term[1]);
if (term[0] == "rem") return done("noreply",current_amount-term[1]);
throw new Error("unexpected request")
});
```