Real World SOA (Austin on Rails)

@hayesdavis Austin on Rails: SOA Real World SOA Hayes Davis
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@hayesdavis Austin on Rails: SOA Why should you listen to
me?

@hayesdavis Austin on Rails: SOA Being dumb & failing

@hayesdavis Austin on Rails: SOA In the beginning

@hayesdavis Austin on Rails: SOA What’s a few more models,
some NoSQL and some rake tasks?

@hayesdavis Austin on Rails: SOA

@hayesdavis Austin on Rails: SOA What should be a service?
• Things that are big context switches • It needs resources your app doesn’t • It does things that are hard to do in Rails • There are clear inputs and outputs

@hayesdavis Austin on Rails: SOA A little better

@hayesdavis Austin on Rails: SOA How SoA saves your ass
• Simpler logic • Simpler deployments • Better division of labor • Easier scaling • Use the right tool/language for the job

@hayesdavis Austin on Rails: SOA How SoA kicks your ass
• More codebases == more dependencies • Data drift • More hardware • Tricky dev environment • Communication complexity

@hayesdavis Austin on Rails: SOA Be as dumb as possible
(but no dumber)

@hayesdavis Austin on Rails: SOA 1) Know as little as
possible

@hayesdavis Austin on Rails: SOA Knowing little • Minimize the
scope of the environment your service knows about • Keep things stateless • Don't store data you don't need

@hayesdavis Austin on Rails: SOA 2) Do as little as
possible

@hayesdavis Austin on Rails: SOA Be lazy for fun and
profit • Don't add speculative functionality • Fail fast on errors • Don't cache

@hayesdavis Austin on Rails: SOA 3) Communicate your ignorance clearly

@hayesdavis Austin on Rails: SOA transport = Thrift::BufferedTransport.new( Thrift::Socket.new('localhost',
9090)) protocol = Thrift::BinaryProtocol.new(transport) client = BookService::Client.new(protocol) transport.open() book = client.get_book(1) transport.close() - or - $ curl http://bookinator:9090/books/1.json {"id": 1, "title": "Cool Story"}

@hayesdavis Austin on Rails: SOA

@hayesdavis Austin on Rails: SOA 4) Be paranoid.

@hayesdavis Austin on Rails: SOA The world is out to
get you • You will get poorly formed data • You will get out of order data • You will get too much data too fast • You will get the same data repeatedly

@hayesdavis Austin on Rails: SOA What can you do? •
Check your inputs • Don't depend on temporal ordering • Be idempotent • Log • Graph

@hayesdavis Austin on Rails: SOA 2013-‐10-‐21 11:44:12 12384 foo::bar ERROR
-‐ OH NOES!

@hayesdavis Austin on Rails: SOA Failure

@hayesdavis Austin on Rails: SOA Your service will fail •
Your hardware will fail • Your network will fail • Your code will fail • They’ll fail hard, soft, in cascades and in ways you never imagined

@hayesdavis Austin on Rails: SOA 1) Treat failure as the
default

@hayesdavis Austin on Rails: SOA Failure as the default •
Make sure you have timeouts • Define separate exceptions for down, timeout, service-level errors • Test clients at HTTP level • Decide how your app will respond when this service is gone

@hayesdavis Austin on Rails: SOA Test clients at HTTP level

@hayesdavis Austin on Rails: SOA 2) If at first you
don't succeed, retry

@hayesdavis Austin on Rails: SOA Not as easy as it
sounds • As a rule, always retry on writes • Under what conditions should you retry? • What kind of backoff? • Avoiding herding

@hayesdavis Austin on Rails: SOA Retriable https://gist.github.com/hayesdavis/7107908

@hayesdavis Austin on Rails: SOA 3) If you can't succeed,
come back in the future

@hayesdavis Austin on Rails: SOA After you retry... • Have
to move on at some point • Service might be 100% down for a while • If possible, keep accepting writes • Queue them for later processing • Consider local read-only or down setting for service

@hayesdavis Austin on Rails: SOA Queue for later if you
can

@hayesdavis Austin on Rails: SOA On being dumb 1. Know
little 2. Do little 3. Communicate clearly 4. Be paranoid

@hayesdavis Austin on Rails: SOA On failing 1. Treat failure
as the default 2. Retry, retry, retry 3. When all else fails, defer

Real World SOA (Austin on Rails)

Real World SOA (Austin on Rails)

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