sysdist

The sample project containing the code for my NodeJS talk about distributed systems.
Please note that this code is no more that a spike I wrote in around 4 days: be gentle with that, and do not run it in production!
I will refactor it, tough, for the next speech :)

what does it do?

What you have here is a process capable to implement some aspects of a key-value store (namely read and write) which does it using a distributed architecture. Following the CAP theorem it can use a CA approach (two-phase commit), an AP approach (sloppy quorums) or a CP approach (majority quorums). Based on the environment variable MODE it will select the operating mode.

what are the basic APIs?

POST /database/:key/:val
create or update a key on the database
GET /database/:key
Returns the value of the key on the database
GET /admin/dump
Dumps the database on screen (useful for demos)
GET /admin/clean
Kind of "cleans" the screen pushing a lot of blank lines (useful for demos)

how does it work?

The whole distributs system is composed of 5 different (potentially) running instances that sit oo host 127.0.0.x:300x, where x ranges from 1 to 5. Just launch node Server.js 3001 for example to start the server on port 3001, repeat for the others, then simply curl using the APIs them to see how it works :) Feel free to kill some servers or to freeze them using iptables (a script is provided for Linux)

are there any scripts?

General use:
bin/get-value.sh
Read the value of the key "city" from server #3001
bin/set-value.sh
Sets the value of the key "city" to a random value on a random server
bin/clean.sh
Invokes the clean screen on all servers
bin/dump.sh
Invokes the database dump on all servers
bin/freeze.sh
Using iptables, freezes the ip related to the port you specified (i.e. freeze.sh 3002 locks 127.0.0.2). Requires root.
bin/unfreeze.sh
Flushes your iptables rules, all your rules will be removed! (iptables -f). Requires root.

Specific for some modes:
bin/trick-value.sh
AP only - tricks the value of the key "city" to something else
bin/propose.sh
AC only - propose a value for a transaction
bin/commit.sh
AC only - rolls back the existing transaction
bin/rollback.sh
AC only - commits the existing transaction

Any hard requirements?

Node 4+ please and Linux with iptables if you want to play with freeze!

Where are the slides?

On slideshare where you can also download them if you need to.

Is there a recording of the speech?

A recording in english can be found on youtube thanks to Geecon.
A recording in italian is also available on youtube thanks to Codemotion.