Microservices: Azure Cosmos DB to rule them all!

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Microservices: Azure Cosmos DB to rule them all! Sylvain Pontoreau

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global.azurebootcamp.net 2 Thanks to our local sponsor William BORDES Yoann GUILLO

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global.azurebootcamp.net 3 Thanks to our international sponsor

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4 http://sylvain.pontoreau.com Meet the Team Microsoft Engineer Paris TypeScript co-organizer Sylvain PONTOREAU Azure App Engineer @spontoreau https://www.linkedin.com/in/spontoreau

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Azure Cosmos DB

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What is Azure Cosmos DB • Cloud Database: https://azure.microsoft.com/en-us/services/cosmos-db/ • Released in may 2017 • Based on Document DB • Multi-model • Globally distributed • High availability • Mathematically viable: https://azure.microsoft.com/en-us/blog/azure-cosmos-db-pushing-the-frontier-of-globally-distributed-databases/ • JavaScript engine embedded

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They are using Azure Cosmos DB

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https://azure.microsoft.com/en-us/blog/how-halo-5-guardians-implemented-social-gameplay-using-azure-documentdb/ Halo & Azure Cosmos DB

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Models

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• Geo-redundancy Globally distributed

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Strong Bounded staleness Session Consistent Prefix Eventual Consistency

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Change Feed Change Feed Event Stream Data

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APIs

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Azure Cosmos DB Account Databases Collections Documents Documents in Azure Cosmos DB

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Azure Cosmos DB SQL Api

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SDKs

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• Open source https://github.com/Azure/azure-cosmos-js • Written in TypeScript • NPM Package • Documentation https://docs.microsoft.com/en-us/javascript/api/@azure/cosmos $ npm install @azure/cosmos Node.js SDK

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const { database} = await client .databases .create({ id: databaseId }); const { container } = await database .container .create({ id: containerId }); const client = new CosmosClient({ endpoint: myEndpoint, auth: { masterKey: myKey } }); CosmosClient, Database & Container

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const querySpec: SqlQuerySpec = { query: "SELECT root.firstName root.lastName FROM root WHERE root.email = @email", parameters: [{ name: "@email", value: "[email protected]" }] }; const { result } = await container .items .query(querySpec) .toArray(); const item = await container .item(id); const { body: readDoc } = item.read(); Querying

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const person = { firstName: "Sylvain", lastName: "PONTOREAU", email: "[email protected]" }; const { body } = await container .items .create(person); if(body !== undefined) { console.log(body.id); } const item = await container .item(body.id); const { body: readDoc } = item.read(); readDoc.email = "[email protected]"; await item.replace(readDoc); await item.delete(); Persistence

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CQRS & Event Sourcing

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Data Driven Development Domain Driven Design Domain Driven Development != Data structure MCD CRUD Behavior Bounded Context Event

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Bounded context Independent Autonomous Loosely coupled

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Query Just a read operation Command Data validation Business logic Persistence CQRS

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CQRS GetOrderById Query UpdateProduct Command GetProducts Query DeleteOrder Command … … Dispatcher Dispatcher QueryHandler CommandHandler Validation Plugin Monitoring Plugin Telemetry Plugin … Eventual consistency

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Consistency • All system nodes needs to manipulate exactly the same data at the same time. Availability Partition tolerance • Requests must succeed. • Node failure must not create a complete system failure. A distributed system can only guarantee 2 constrains at the same time, not 3 Eventual consistency?

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https://martinfowler.com/eaaDev/EventSourcing.html Event Sourcing

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CQRS & Event Sourcing GetOrderById Query UpdateProduct Command GetProducts Query DeleteOrder Command … … Dispatcher Dispatcher QueryHandler CommandHandler Projection Projection Aggregate State Events

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Cosmos DB as an Event Store Read Enpoint Write Enpoint Event Store Projector Read DB publish trigger persist query

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Demo

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Resources https://docs.microsoft.com/en-us/azure/cosmos-db/introduction https://docs.microsoft.com/en-us/azure/cosmos-db/create-sql-api-nodejs https://docs.microsoft.com/en-us/azure/cosmos-db/change-feed https://medium.com/@thomasweiss_io/planet-scale-event-sourcing-with-azure- cosmos-db-48a557757c8d https://www.youtube.com/watch?v=5YNJpGwj_Zs https://docs.microsoft.com/en-US/azure/architecture/patterns/cqrs https://docs.microsoft.com/en-us/azure/architecture/patterns/event-sourcing https://docs.microsoft.com/en- us/dotnet/standard/microservices-architecture/microservice-ddd-cqrs-patterns/ https://docs.nestjs.com/recipes/cqrs https://gitpitch.com/jrouaix/cqrs-es-presentation/master#/ https://www.youtube.com/watch?v=qBLtZN3p3FU https://www.youtube.com/watch?v=LDW0QWie21s