Rethinking Reactive Architectures with GraphQL

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WeAreDevelopers Live Days Remote, March 2021 Rethinking Reactive Architectures with GraphQL

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@duffleit @duffleit david.leitner@squer.at David Leitner Coding Architect

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Reactive? Programming with, or designing upon, asynchronous data streams.

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asynchronous data streams. Space Time Collections Iterator Generator Value Getter Setter Promise Deferred Resolver Stream Reader Emitter

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Counter and Doubled should be bound.

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the Destiny Operator Counter and Doubled should be bound. ⬅

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1 map(x => x*2) 2 3 6 the Destiny Operator Counter and Doubled should be bound.

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the Destiny Operator Counter and Doubled should be bound.

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the Destiny Operator Counter and Doubled should be bound.

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Stream Caller Receiver propagate change observe change The reactive programming paradigm is based on asynchronous streams which propagate change.

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YAMS — Yet Another Mail Service NEW 2021-04-11 — An important Email 2021-04-09 — Another important Email 2021-04-08 — Do you want to join my network? 2021-04-05 — Nigerian prince wants to send you money X your inbox contains 4 mails 1 NEW Mail Reload Controller Rest Client update UI Element update UI update UI

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YAMS — Yet Another Mail Service NEW 2021-04-11 — An important Email 2021-04-09 — Another important Email 2021-04-08 — Do you want to join my network? 2021-04-05 — Nigerian prince wants to send you money X your inbox contains 4 mails 1 NEW Mail Reload Websocket Client Email Email count() count() collect() filter() subscribe Email map()

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YAMS — Yet Another Mail Service NEW 2021-04-11 — Hello WeAreDevelopers! 👋 2021-04-09 — Another important Email 2021-04-08 — Do you want to join my network? 2021-04-05 — Nigerian prince wants to send you money X your inbox contains 5 mails 2 NEW Mail Websocket Client Email Email count() count() collect() filter() subscribe Email NEW 2021-04-11 — An important Email map()

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We move from a pull-based design, to an asynchronous push-based design.

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Reactive Programming ✅ Reactive Architectures 🥺 We take the same concepts from reactive programming and move them up to the system architecture. 🤞

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The Reactive Manifesto Responsive Responsive NFR

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Internet has 4.7 Billion users. Facbook has 2.8 Billion users. Youtube has 2.1 Billion users. 2010 2020 The Internet has 1.4 Billion users. A single website may now handle twice as much traﬃc as the entire internet did a decade ago.

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The Reactive Manifesto Message Driven Responsive Elastic Resilient NFR Support Enable Scalability Extendibility

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Microservice A Microservice B Message Driven Responsive Elastic Resilient Value Form Means

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Microservice A Microservice B Message Driven Responsive Elastic Resilient Value Form Means Microservice B

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Microservice A Microservice B Message Driven Responsive Elastic Resilient Value Form Means Microservice B Stream

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Microservice A Microservice B Message Driven Responsive Elastic Resilient Value Form Means

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Message Driven Responsive Elastic Resilient Value Form Means Microservice A Stream Microservice B

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We are resilient by supporting Back-Pressure Stream Provider Consumer events are stored until consumed Stream Provider Consumer A Consumer C Consumer B scaling out consumers We can scale-out by Location Transparency

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We move from a synchronous pull-based architecture, to an asynchronous push-based architecture.

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Microservice A Microservice B Microservice C Web Application Microservice C with high latency First Generation MicroServices Synchronous and without Backpressure Support

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Microservice A Microservice B Microservice C Web Application Microservice C with high latency Second Generation MicroServices Partially asynchronous with Queues Queue isolates bottleneck Queue Microservice C with high latency

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Web Application Stream Microservice usually Backend-For-Frontend (BFF) Microservice A Microservice B Microservice C Third Generation MicroServices Fully asynchronous & stream-centric

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Events as the System State Stream of Transactions Max sent David 100€ Max sent Maria 70€ David sent Maria 25€ User Balance David + 75 € Max - 170 € Maria + 95 € ➡ Event Sourcing 100% reliable audit log.

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Web Application Stream Microservice usually Backend-For-Frontend (BFF) Microservice A Microservice B Microservice C

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Web Application Eventstore Microservice usually Backend-For-Frontend (BFF) Microservice A Microservice B Microservice C

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Web Application Eventstore Microservice usually Backend-For-Frontend (BFF) FaaS A FaaS B FaaS C Forth Generation MicroServices EventSourced with FaaS

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FaaS A Web Application FaaS B FaaS C Eventstore Microservice often Backend-For-Frontend (BFF) HTTP Streaming Request/Response

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GraphQL ✅ Consumer Driven APIs ✅ Native Schema Support ✅ Streaming Support

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Streaming with GraphQL ➡

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Lambda A Web Application Lambda B Lambda C Eventstore Microservice often Backend-For-Frontend (BFF) HTTP Streaming Request/Response

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Lambda A Web Application Lambda B Lambda C Eventstore GraphQL Streaming Request/Response

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Lambda A Web Application Lambda B Lambda C Eventstore GraphQL Microservice A Microservice B Microservice C Web Application ➡ pull-based push-based

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Insurance Portal Example 🚗 👩💻

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Lambda A Lambda B Lambda C GraphQL Step 1 Step 2 Step 2 Car Brand Build Year Car Model Insurance Agent Customer ✅ This Is Correct Alfra Romeo Giulia, 2020 110PS, Diesel Step 1 Step 2 Step 2 Coverage 200 € 🏁 Sign Digital Do you accept 70% coverage for 200€? Eventstore GraphQL

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GraphQL Step 1 Step 2 Step 2 Car Brand Build Year Car Model Lambda A Insurance Agent Lambda B Lambda C Eventstore GraphQL Customer ✅ This Is Correct Alfra Romeo Giulia, 2020 110PS, Diesel Step 1 Step 2 Step 2 Coverage 250 € 🏁 Sign Digital Do you accept full coverage for 250€? Customers expect realtime syncronisation between channels.

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Mobile Banking Example 📱 💵

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Mobile Banking Usage Show balance & last transactions: 93% Initiate new payment: 3% Any other functionality: 4%

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Microservice A Web Banking Microservice B Microservice C Eventstore GraphQL Projection Projections 1⃣ Projections act as read-models for a speciﬁc client. 2⃣ They subscribe to events & hydrate the projection. 3⃣ The client only reads from the projection.

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GraphQL Mobile Client Projection Microservice A Web Banking Microservice B Microservice C Eventstore GraphQL Projection Projections 1⃣ Projections act as read-models for a speciﬁc client. 2⃣ They subscribe to events & hydrate the projection. 3⃣ The client only reads from the projection. Show balance & last transactions: 93%

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The Reactive Manifesto Message Driven Responsive Elastic Resilient NFR Supported by Enabled by Scalability Extendibility

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This stuﬀ is cool, but think twice, & ensure that reactive architectures really ﬁt your problem at hand.

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Architectural Styles buy you options Reactive Architectures buy you mainly Resilience, Realtime Capabilities, Elasticity, & Extendibility. you pay by complexity. 💵

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Maybe start small, and shift to reactive systems once needed.

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@duffleit @duffleit david.leitner@squer.at David Leitner Coding Architect

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squer.link/kafka