All hope abandon ye who enters here

1. Monolith is hard to work on:
   • Iterations are slow
   • Releases are hard (code changes from under you)
2. Different components of the system should have different performance targets:
   • Written in different languages
   • Run on different machines
3. Migration difficulty:
   • Maintain public API contracts
4. Microservices shift complexity into the network:
   • Who calls who?
   • Many moving parts to fulfill simple requests
5. Monzo:
   • 1500 services
6. Should we start with Microservices? (it depends)
   • Cost of replacing one part is low
   • Monolith is more flexible in restructuring
7. Splitting:
   • Bounded Contexts:
     • From Domain Driven Design by Eric Evans
     • Idea of a context (a model of what we are trying to do)
     • Split the services based on what they do
     • Product teams (think THG)
   • Conway's Law:
     • Systems reflect the communication process between teams
   • Airbnb:
     • They kept a lot of their code themselves
     • Intercepted a call and redirected what it did
     • Routing events produced by the databases
8. Monorepo vs Multi-repo:
   • Every developer has all the code checked out
   • A lot more management overhead
   • Do not recompile all of the code
   • As always, it depends...
9. Strangler Pattern:
   • Write stuff "around" the existing system
   • Intercept requests and reroute them to new systems
   • Nginx proxy could do that for you
10. When to redactor a system and when to rewrite it?

1. A system where the cloud is the primary deployment system
2. Reasons:
   • Lots of services available
   • Scaling is easy
   • Dynamic scaling is easy (load in the morning, nothing for the rest of the day)
   • CapEX VS OpEX --> Less capital involvement
3. Spectrum:
   • IAAS -- infrastructure as a service
   • CoAAS -- Container as a service
   • PAAS -- platform as a service
   • FAAS -- function as a service
4. Containers: -

1. Sam Newman:
   • Building Microservices
   • Monolith to Microservices
2. Intro:
   1. Microservices in modern world
   2. What problem are they solving
   3. Why they may be a worse choice for a company
   4. Microservices should reflect internal company structure

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