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what if we simplify each to binary: we get 8 permutations (1) epic saga (2) fantasy fiction saga (3) fairy tale saga (4) parallel saga (5) phone tag saga (6) horror story saga (7) time travel saga (8) anthology saga transactional boundary Article: 8 fallacies of distributed computing 9 10 compensating updates always work (1) epic saga first attempt at saga error: compensating updates !...
Data Ownership Data Access Data Ownership the owner is the one who writes to the table Model_ 3 data ownership patterns (in microservice architecture) Data Access Model_ 4 data access patterns (in microservice architecture)
what if we simplify each to binary: we get 8 permutations (1) Sagas dimensions of change Model_ 8 types of sagas hybrid sagas (2) sharding example: concert tickets example: sysops experts (1) Sagas dimensions of change Any change to any of these 3 forces, changes everything… treat as binary for simplicity then we get: Model_ 8 types of sagas epic saga fantasy fiction saga fairy tale saga parallel saga phone tag saga horror story saga time travel saga anthology saga !...
if the semantics of your problem change then everything else needs to change prevent implementation coupling, that makes your architecture brittle contracts: strict vs loose method calls “schema” serialized objects RPC remote procedure call graphql (aggregation framework, not a invocation framework) value-driven contracts json KVP key value pairs example: brittleness not brittle: changing the type of country, does not break the contract for wishlist support all versions forever?...
Model_ 5 service disintegrators Model_ 3 granularity integrators
What is async? async implies events or messages Distinction_ events vs messages Why async? improves responsiveness (not performance - Distinction_ responsiveness vs performance) async usually works well in happy path, but get’s more complicated in the unhappy path… happy path -> works well unhappy path: eg.“comment uses a word that is not allowed” new user flow: send email? notification to user? automate correction censor that word *****
orchestration: conductor at musical orchestra choreography: dancers Orchestration single point of failure services depend on orchestrator lots of communication order placement needs to be highly available orchestrator needs to be highly available order placements needs to be highly available smaller orchestrator (vs Enterprise Service Bus) eg. Order Placement Orchestrator, Order Cancellation Orchestrator logic shifts to the orchestrator error handling becomes a design decision in the orchestrator? in the service?...
Architecture: The Hard Parts How do I determine the appropriate level of service granularity? service granularity How do I achieve high semantic coupling and low implementation coupling? semantic vs implementation coupling How do I create bounded contexts and access data I don’t own? bounded contexts and access data I don’t own How do I decide between synchronous versus asynchronous communication? synchronous vs asynchronous communication How do I choose between choreography and orchestration for my workflow?...
(free src: https://learn.particular.net/courses/take/SOA/lessons/1517272-it-ops-service ) Course_ Advanced Distributed System Design - Udi Dahan ToC SOA tenets Service example _) Q&A (no notes, not in free src) Services modelling: Workflows, boundaries and business capabilities UI composition and Branding service IT/Ops service related: Service Boundaries, SOA vs DDD - DDDEU2021 Session_ Service Boundaries - Tjen Wellens 1) SOA Tenets Microsoft original “tenets of SO” 1. autonomous 2. explicit boundaries 3. share contract & schema not class or type (or anything, or db) 4....
Views logical process development physical (aka deployment) +1 = scenarios (aka use cases) (src: Course_ ADSD - Intro to SOA)