Arrrr Me Hearty! Sailing the Seas of DRb in a Shoe

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ARRRR ME HEARTY! Sailing the Seas of DRb in a Shoe Davy Stevenson Eric Hodel Rein Henrichs @davystevenson @drbrain @reinh RubyConf 2013

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Spaceteam? Who has played? Pleiades by Jim Keller

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Spaceteam trailer

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Why DRb? Easy Interprocess Communication Send and Get Data Peer to Peer Red Beach by alphadesigner

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Why Rinda? Flexible Automatic discovery No explicit destination? Throw it in the tuplespace Farmhouse and Roosting Birds at Dusk by Trey Ratcliff

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Why Shoes? Needs some love and attention Perfect showcase for distributed code Support non-web Ruby development! Freestyle Converse by Daniele Margaroli

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Why Pirates? Yarrr! Mutiny by Shane Gorski

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Preparation Install jruby (1.7.4-6 all should work) Install shoes4 $ git clone https://github.com/shoes/shoes4 $ git checkout 7d0a1ee $ gem build shoes.gemspec $ gem install shoes-4.0.0.pre1 $ alias shoes4='/path/to/shoes4/bin/shoes' Install pirate_game $ gem install pirate_game

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Preparation Also in pirate_game README! https://github.com/davy/pirate_game

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DRb RMI for Ruby Written by Masatoshi SEKI require ‘drb’ Remote objects act like local objects It’s “Ruby Throated” Tuesday! by MrClean1982

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Remote Array Server array = [] # share the array DRb::DRbServer.new nil, array # print the URI (we let DRb pick) puts DRb.uri # wait for ^C DRb.thread.join

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Remote Array Peer # create remote array reference remote_array = DRbObject.new_with_uri ARGV.shift # append to remote array remote_array << "a" remote_array.push "b", "c"

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Remote Array Peer # create remote array reference remote_array = DRbObject.new_with_uri ARGV.shift puts remote_array.join ", " # => a, b, c

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Rinda Linda for Ruby Model for distributed programming require ‘rinda/ tuple_space’ Stores tuples with arbitrary data write, take, read Quasicabinet by Aranda\Lasch

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Tuple Space # blocking operation with template @ts.take [:button, "Keel", (now...now + 30), nil] # writing a matching tuple unblocks @ts.write [:button, "Keel", Time.now.to_i, DRb.uri]

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Service Discovery Rinda::RingFinger, Rinda::RingServer TupleSpace for registry Broadcast, unicast, multicast (Ruby 2.1) Rinda::RingProvider Wrapper for advertisement

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Shoes Created by _why Simple cross- platform GUI toolkit for Ruby Shoes4 is an all- Ruby rewrite Still under active development Blue Power! by Éole Wind

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Shoes Manual Layout Input elements Drawing Animate / Move / Events http://shoesrb.com/manual/Hello.html

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Display Issues Not all movement methods have been implemented on all types of objects Can move, but not displace Width/height =( Show/hide/toggle missing =(

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Animations Animations run in parallel Need to manually manage them start, stop, remove PROTIP™: Separate drawing from animation

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Give Back Complicated Shoes app highlights regressions Use game to detect & ﬁx issues

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Open Source Three Gems! github.com/davy/ pirate_command github.com/davy/ shuttlecraft github.com/davy/ pirate_game Coast Guard by Mike Baird

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pirate_command PirateCommand.generate => "Swab the Poop Deck" PirateCommand.action => "Batten" PirateCommand.thing => "Main Sail" PirateCommand.exclaim => "Ahoy" PirateCommand.exclaim! => "Shiver me Timbers!"

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pirate_command github.com/davy/pirate_command

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shuttlecraft Create distributed systems with Rinda Simpliﬁes registration Keeps track of registered clients Easily send messages

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shuttlecraft github.com/davy/shuttlecraft

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pirate_game Play the game!

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pirate_game github.com/davy/pirate_game

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Game Architecture? Does exactly what the GM instructs Game Master Game Handles all logic Issue cmds to game, game sends response

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That’s no fun! Distributed services FTW Lightning by Fadzly Mubin

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Game Architecture Registration Layout generation Issuing actions & gathering responses

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Yay Diagrams! Game Game Master Rinda Tuplespace

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Registration

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Registration write [:name, ‘Foo’, uri’]

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Registration write write [:name, ‘Foo’, uri’] [:name, ‘Bar’, uri’]

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Registration write write write [:name, ‘Foo’, uri’] [:name, ‘Bar’, uri’] [:name, ‘Baz’, uri’]

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Registration write write write [:name, ‘Foo’, uri’] [:name, ‘Bar’, uri’] [:name, ‘Baz’, uri’] read_all

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Layout Generation GM sends each game their bridge and list of all bridge items my_items all_items my_items all_items direct DRb

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Action & Response

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Action & Response watch for actions take (blocks)

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Action & Response ‘Haul the Keel’ watch for actions take (blocks)

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Action & Response watch for button click take (blocks) watch for actions take (blocks)

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Action & Response watch for button click on button click [:button, ‘Keel’, timestamp, from] write take (blocks) watch for actions take (blocks)

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Action & Response watch for button click [:button, ‘Keel’, timestamp, from] take (blocks) watch for actions take (blocks)

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Action & Response watch for button click watch for actions take (blocks) write [:action, ‘Keel’, timestamp, from]

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Action & Response watch for button click watch for actions take (blocks) [:action, ‘Keel’, timestamp, from]

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Action & Response watch for button click watch for actions

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Architecture Diagram mothership game_master client client_app master_app shuttlecraft

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Enough Jibber Jabber Let’s get to the important parts GAME TIME Shut up you fool! by Andre Vandal

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Preparation (again) Install jruby (1.7.4-6 all should work) Install shoes4 $ git clone https://github.com/shoes/shoes4 $ git checkout 7d0a1ee $ gem build shoes.gemspec $ gem install shoes-4.0.0.pre1 $ alias shoes4='/path/to/shoes4/bin/shoes'

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Install Install pirate_game $ gem install pirate_game

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Networking Theoretically this should work on conference wiﬁ *But* for best results use a personal access point

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RingServer Someone needs to run a ringserver $ ring_server But not too many Try not to screw it up We are working on it

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Game Master Only one needed per game Pick a good name If GM crashes, game is stranded =(

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Pirate Game! 1* to 4 players *Totally a ‘feature’ not a bug

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Find Your Game GMs are found by Rinda service discovery

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Find Your Game ISSUE: If join fails you will not receive an error message and will enter empty disconnected pub =(

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Pirate Pub Chat with your friends in the Pirate Pub* *Yes, you have to click the ‘Send’ button. No keybindings?!? =(

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Pirate Pub ISSUE: At the moment the GM needs to trigger each stage. Future development should switch over to Spaceteam-like mechanism where each player indicates that they are ready to proceed

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Sail the High Seas Keep the ship aﬂoat! Work together to man the ship Beware of bad weather!

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Security DRb Priorities: Transparency Easy of use … Security Pirates by Adrien Sifre

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Full Access Clients can do anything Get remote nil instance_eval github.com/drbrain/drb-worm

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Message-level Security DRb::DRbServer::INSECURE_METHOD Opt-out $SAFE Relies on tainting

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DRb over UNIX Socket Restricted to one host Filesystem permissions control access No network access

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Access Control List Deny or allow by IP address and range Diﬃcult to manage No privacy

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DRb over SSL X509 certiﬁcate Full privacy Diﬃcult to manage

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chroot Filesystem sandbox Can’t write outside Can still consume CPU, create processes

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Best Practices Verify your peers Limit accessibility Use a private network

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drbdump tcpdump for DRb Message sends Message latency Message allocations Colorful toy trucks parked together in rows by Horia Varlan

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Problems Out-of-order TCP mDNS Ruby 2.1 No ﬁltering IPv6 (bug)

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Running Basic drbdump Summary of 10,000 messages drbdump -q -n -c 10000 Listen only on loopback drbdump -i lo0

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Timestamp 17:34:49.546074 "druby://192.0.2.1:60919" 㱺 ("druby://192.0.2.1:60913", 70180390657240). respond_to?(:update, false)

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Source 17:34:49.546074 "druby://192.0.2.1:60919" 㱺 ("druby://192.0.2.1:60913", 70180390657240). respond_to?(:update, false)

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Message-send 17:34:49.546074 "druby://192.0.2.1:60919" 㱺 ("druby://192.0.2.1:60913", 70180390657240). respond_to?(:update, false)

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Receiver 17:34:49.546074 "druby://192.0.2.1:60919" 㱺 ("druby://192.0.2.1:60913", 70180390657240). respond_to?(:update, false)

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Message Name 17:34:49.546074 "druby://192.0.2.1:60919" 㱺 ("druby://192.0.2.1:60913", 70180390657240). respond_to?(:update, false)

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Arguments 17:34:49.546074 "druby://192.0.2.1:60919" 㱺 ("druby://192.0.2.1:60913", 70180390657240). respond_to?(:update, false)

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Timestamp 17:34:49.546531 "druby://192.0.2.1:60919" ⾨ "druby://192.0.2.1:60913" success: true

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Destination 17:34:49.546531 "druby://192.0.2.1:60919" ⾨ "druby://192.0.2.1:60913" success: true

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Message-result 17:34:49.546531 "druby://192.0.2.1:60919" ⾨ "druby://192.0.2.1:60913" success: true

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Source 17:34:49.546531 "druby://192.0.2.1:60919" ⾨ "druby://192.0.2.1:60913" success: true

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Status 17:34:49.546531 "druby://192.0.2.1:60919" ⾨ "druby://192.0.2.1:60913" success: true

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Result Object 17:34:49.546531 "druby://192.0.2.1:60919" ⾨ "druby://192.0.2.1:60913" success: true

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Exception 17:34:49.563440 "druby://192.0.2.1:60929" ⤂ "druby://192.0.2.1:60920" exception: #

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Exception Object 17:34:49.563440 "druby://192.0.2.1:60929" ⤂ "druby://192.0.2.1:60920" exception: #

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Easy to Match "druby://192.0.2.1:60919" 㱺 ("druby://192.0.2.1:60913" "druby://192.0.2.1:60919" ⾨ "druby://192.0.2.1:60913" "druby://192.0.2.1:60929" 㱺 ("druby://192.0.2.1:60920" "druby://192.0.2.1:60929" ⤂ "druby://192.0.2.1:60920"

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Statistics Output Basic statistics Packets, messages, results Message statistics Allocations, latency Peer statistics Latency

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Basic Statistics 1508 total packets captured 0 Rinda packets captured 56 DRb packets captured 30 messages sent 26 results received 2 exceptions raised

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Message Statistics Messages sent min, avg, max, stddev: call (1 args) 10 sent; 3.0, 6.2, 19.0, 6.7 allocations; 0.285, 1.479, 7.258, 2.171 ms

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drbdump Diagnostics Find message spam Find hanging calls Verify expected behavior

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Future Want to pitch in? Wilma was here by zanzibar

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Group Activities Raid a ship? Survive a hurricane? Steer ship with the wheel

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Character Generation Build a pirate? Select: Beard Parrot Eyepatch Hair

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Infrastructure Improvement Automatic Integrated Game Master Better Error Handling Easy Game Restart

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Play! Contribute! Thanks! =D The Flying Dutchman by Scott Smith