Herding Code 210: Ian Cooper on Microservices and the Brighter library

Episode 210

While at NDC Oslo, K Scott and Jon talked to Ian Cooper about Microservices and using the Brighter library for Command Dispatcher / Command Processor patterns.

Download / Listen: Herding Code 210: Ian Cooper on Microservices and the Brighter library

Show Notes:

• Why Microservices?
  • (0:48) Ian explains that "micro" doesn't imply number of lines of code but "A bounded concept/business capability within your Domain" (put forth by Martin Fowler and James Lewis)
  • (1:20) Ian talks about breaking the domain problem down further and further for simpler testing, better fault tolerance and incremental releases.
  • (2:20) "If you can't QA everything you need to be able to monitor and respond to issues rapidly."
  • (2:42) Scott Allen asks if Devops is a driver for Microservices rather than physical deployment or team size.
  • (3:00) Ian talks about the scale limits of developers and teams and how component based architectures.
• Have we been here before?
  • (4:00) Ian talks about how Microservices is the next generation of component-based architectures after DCOM, CORBA, SOA and the importance of understanding what worked, what didn't and why.
  • (4:49) Asking a component for a cup of tea vs telling something how to make tea highlighting the difference between Microservices vs RPC. RPC was very coupled to behavior which lead to fragile APIs.
• Finding the "micro" sweet spot
  • (5:50) Jon asks how you manage the complexity of orchestrating many smaller pieces.
  • (6:15) Ian advises against going too small - Nanoservices - where the overhead of a service overshadows the utility value of it.
  • (6:30) "It's really hard to get a feel in a new domain of where those points are that you can slice effectively" - one solution is to start exploring the domain in a traditional monolithic way and to break the parts apart at the seems to get the tradeoff right.
• Tooling and support
  • (7:06) Jon asks what a good way to manage these services including profiling and monitoring.
  • (7:20) Ian recommends some tools to help:
    • New Relic for introspective monitoring and diagnostics.
    • Logstash or Splunk for log analysis and the usefulness of adding a GUID to a request that flows through messages and logs to correlate the activity.
    • Zookeeper or Consul for service registration and discovery.
  • (8:28) Scott Allen and Ian talk about how Microservices take forward SOA principles such as autonomous services, not sharing types and stable interfaces.
  • (9:00) Scott Allen asks what options for communications between the services are and Ian compares HTTP, Sockets and message queues like RabbitMQ.
• Ian's Brighter .NET lightweight Microservices project
  • (10:20) Basic two parts of Brighter are:
    • Command Dispatcher/Processor - Maps a command to a processor with a pipeline where you can insert orthogonal operations like logging and monitoring
    • Task Queue - Allows some commands will be handled asynchronously elsewhere
  • Very simple for the developer - just write a command and a handler.
  • Easy to embed in your existing Windows service if using something like Topshelf.
  • Provides timeouts, retries and a circuit breaker inspired by Netflix's Hystrix in a declarative manner.
  • (12:45) Scott Allen clarifies how easy it is to get two services talking to each other using this via RabbitMQ.
  • (13:00) Ian talks about future support for Azure Service Bus and the possibility of producing one for Redis - RabbitMQ and Amazon SQS are already supported.
  • (13:30) Scott Allen asks if this is used in production and Ian explains how Huddle started with using RX on the server and had difficulties managing subscriptions.
  • (14:20) Brighter is on ThoughtWorks Technology Radar and evangelized by ex-Huddlers at their new roles.
  • (14:40) Ian talks about the importance of good documentation and welcomes feedback on theirs.
  • (15:10) Ian mentions they facilitate hexagonal architecture.
  • Scott Allen asks if you can use in-process and Ian explains the subtleties
• Wrap-up
  • (16:00) Ian's time is sucked up by being a a new dad, congratulations!
  • (16:30) The one job of a parent is keeping children alive.
  • (16:40) Thank-you and goodbye.

Show Links:

• Fowler & Lewis on Microservices
• New Relic for .NET documentation
• Decoupling from ASP.NET - Hexagonal Architecture with Ian Cooper at NDC 2014
• Chris Fidao on Hexagonal Architecture

These show notes were contributed by Damien Guard. Thanks!