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

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

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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

Azure Cosmos DB

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

They are using Azure Cosmos DB

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

Models

• Geo-redundancy Globally distributed

Strong Bounded staleness Session Consistent Prefix Eventual Consistency

Change Feed Change Feed Event Stream Data

APIs

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

Azure Cosmos DB SQL Api

SDKs

• 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

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

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

const person = { firstName: "Sylvain", lastName: "PONTOREAU", email: "sypontor@microsoft.com" }; 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 = "sylvain@microsoft.com"; await item.replace(readDoc); await item.delete(); Persistence

CQRS & Event Sourcing

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

Bounded context Independent Autonomous Loosely coupled

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

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

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?

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

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

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

Demo

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

Questions?

33 Merci d’être venus A bientôt !