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KAMMYSLIWIEC TAMING REACTIVE NODE.JS: STREAM-ORIENTED ARCHITECTURE WITH NEST

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KAMMYSLIWIEC KAMIL MYSLIWIEC NESTJS CREATOR | CO-FOUNDER OF TRILON.IO
 @KAMMYSLIWIEC


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KAMIL MYŚLIWIEC SOFTWARE ENGINEER
 @KAMMYSLIWIEC


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KAMMYSLIWIEC Adonis Express Koa Nest Fastify

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KAMMYSLIWIEC NESTJS WWW.NESTJS.COM
 @NESTFRAMEWORK


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KAMMYSLIWIEC STREAM-ORIENTED
 ARCHITECTURE

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KAMMYSLIWIEC 1 2 3 X

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THINKING REACTIVELY

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KAMMYSLIWIEC ADVANTAGES

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KAMMYSLIWIEC READABILITY

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KAMMYSLIWIEC LOOSELY COUPLED
 ARCHITECTURE

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SELF-DESCRIBABLE

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KAMMYSLIWIEC DISADVANTAGES

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KAMMYSLIWIEC COMPLEXITY

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KAMMYSLIWIEC REDUX

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EXAMPLE

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KAMMYSLIWIEC

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KAMMYSLIWIEC https://localhost:3000/dragons https://localhost:3000/dragons/:id https://localhost:3000/heroes https://localhost:3000/heroes/:id https://localhost:3000/heroes/:id/slay-dragon

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KAMMYSLIWIEC export interface SlayDragonDto { dragonId: string; }

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KAMMYSLIWIEC LAYERED 
 ARCHITECTURE

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KAMMYSLIWIEC CONTROLLER DATA
 ACCESS SERVICE

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KAMMYSLIWIEC @Patch(‘:heroId/slay-dragon‘) async slayDragon( @Param('heroId') heroId: string, @Body('dragonId') dragonId: string, ) { await this.heroesService.slayDragon(heroId, dragonId); }

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KAMMYSLIWIEC @Patch(‘:heroId/slay-dragon‘) async slayDragon( @Param('heroId') heroId: string, @Body('dragonId') dragonId: string, ) { await this.heroesService.slayDragon(heroId, dragonId); }

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KAMMYSLIWIEC @Patch(‘:heroId/slay-dragon‘) async slayDragon( @Param('heroId') heroId: string, @Body('dragonId') dragonId: string, ) { await this.heroesService.slayDragon(heroId, dragonId); }

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KAMMYSLIWIEC SERVICE

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KAMMYSLIWIEC const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.experience += dragon.level * 100; dragon.isAlive = false; await Promise.all([ this.heroesRepository.save(hero), this.dragonsRepository.save(dragon), ]);

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KAMMYSLIWIEC const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.experience += dragon.level * 100; dragon.isAlive = false; await Promise.all([ this.heroesRepository.save(hero), this.dragonsRepository.save(dragon), ]);

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KAMMYSLIWIEC const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.experience += dragon.level * 100; dragon.isAlive = false; await Promise.all([ this.heroesRepository.save(hero), this.dragonsRepository.save(dragon), ]);

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KAMMYSLIWIEC const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.experience += dragon.level * 100; dragon.isAlive = false; await Promise.all([ this.heroesRepository.save(hero), this.dragonsRepository.save(dragon), ]); TRANSACTION

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KAMMYSLIWIEC MORE FEATURES

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ARTIFACTS

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KAMMYSLIWIEC hero.experience += dragon.level * 100; dragon.isAlive = false; if (dragon.level >= 3) { const item = await this.itemsService.getRandomItem(); hero.items = hero.items.concat(item); }

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COINS

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KAMMYSLIWIEC hero.experience += dragon.level * 100; dragon.isAlive = false; if (Math.random() < 0.3) { hero.coins += Math.floor(Math.random() * 101) + 100; }

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KAMMYSLIWIEC if (dragon.level >= 3) { const item = await this.itemsService.getRandomItem(); hero.items = hero.items.concat(item); if (Math.random() < 0.3) { hero.coins += Math.floor(Math.random() * 101) + 100; } }

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KAMMYSLIWIEC STREAM-ORIENTED ARCHITECTURE

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KAMMYSLIWIEC @Patch(‘:heroId/slay-dragon‘) async slayDragon( @Param('heroId') heroId: string, @Body('dragonId') dragonId: string, ) { await this.heroesService.slayDragon(heroId, dragonId); }

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KAMMYSLIWIEC @Patch(‘:heroId/slay-dragon‘) async slayDragon( @Param('heroId') heroId: string, @Body('dragonId') dragonId: string, ) { await this.commandBus.execute( new SlayDragonCommand({ heroId, dragonId }), ); }

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KAMMYSLIWIEC COMMAND
 HANDLER

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KAMMYSLIWIEC @CommandHandler(SlayDragonCommand) export class SlayDragonHandler implements ICommandHandler {}

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KAMMYSLIWIEC @CommandHandler(SlayDragonCommand) export class SlayDragonHandler implements ICommandHandler {}

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KAMMYSLIWIEC async execute(command: SlayDragonCommand) { const { heroId, dragonId } = command; const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.experience += dragon.level * 100; dragon.isAlive = false; }

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KAMMYSLIWIEC async execute(command: SlayDragonCommand) { const { heroId, dragonId } = command; const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.experience += dragon.level * 100; dragon.isAlive = false; }

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KAMMYSLIWIEC async execute(command: SlayDragonCommand) { const { heroId, dragonId } = command; const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.experience += dragon.level * 100; dragon.isAlive = false; }

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KAMMYSLIWIEC async execute(command: SlayDragonCommand) { const { heroId, dragonId } = command; const [hero, dragon] = await Promise.all([ this.heroesRepository.findOneById(heroId), this.dragonsRepository.findOneById(dragonId), ]); hero.slayDragon(dragon); hero.commit(); }

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KAMMYSLIWIEC slayDragon(dragon: Dragon) { this.experience += dragon.level * 100; dragon.isAlive = false; this.apply(new HeroSlayedDragonEvent({ heroId: this.id, dragonId: dragon.id, dragonLevel: dragon.level, expPoints: this.experience, })); }

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KAMMYSLIWIEC slayDragon(dragon: Dragon) { this.experience += dragon.level * 100; dragon.isAlive = false; this.apply(new HeroSlayedDragonEvent({ heroId: this.id, dragonId: dragon.id, dragonLevel: dragon.level, expPoints: this.experience, })); }

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KAMMYSLIWIEC COMMAND COMMAND
 HANDLER EVENT EVENT EVENT EVENT
 HANDLER EVENT
 HANDLER EVENT
 HANDLER

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KAMMYSLIWIEC EVENT
 HANDLER

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KAMMYSLIWIEC @EventsHandler(HeroSlayedDragonEvent) export class HeroSlayedDragonHandler implements IEventHandler {}

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KAMMYSLIWIEC @EventsHandler(HeroSlayedDragonEvent) export class HeroSlayedDragonHandler implements IEventHandler {}

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KAMMYSLIWIEC async handle(event: HeroSlayedDragonEvent) { // persistence logic }

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KAMMYSLIWIEC async handle(event: HeroKilledDragonEvent) { const { heroId, dragonId, expPoints } = event; await Promise.all([ this.heroesRepository.update(heroId, { experience: expPoints }), this.dragonsRepository.update(dragonId, { isAlive: false }), ]); }

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KAMMYSLIWIEC async handle(event: HeroSlayedDragonEvent) { // business logic await this.eventsStore.save(event); }

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KAMMYSLIWIEC MORE FEATURES

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KAMMYSLIWIEC COMMAND COMMAND
 HANDLER EVENT EVENT EVENT EVENT
 HANDLER EVENT
 HANDLER EVENT
 HANDLER SAGAS

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ARTIFACTS

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KAMMYSLIWIEC @Saga() dropItem = (events$: Observable) => events$.pipe( ofType(HeroSlayedDragonEvent), filter(({ dragonLevel }) => dragonLevel >= 3), map(({ heroId }) => new DropItemCommand({ heroId })), );

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KAMMYSLIWIEC @Saga() dropItem = (events$: Observable) => events$.pipe( ofType(HeroSlayedDragonEvent), filter(({ dragonLevel }) => dragonLevel >= 3), map(({ heroId }) => new DropItemCommand({ heroId })), );

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KAMMYSLIWIEC @Saga() dropItem = (events$: Observable) => events$.pipe( ofType(HeroSlayedDragonEvent), filter(({ dragonLevel }) => dragonLevel >= 3), map(({ heroId }) => new DropItemCommand({ heroId })), );

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KAMMYSLIWIEC @Saga() dropItem = (events$: Observable) => events$.pipe( ofType(HeroSlayedDragonEvent), filter(({ dragonLevel }) => dragonLevel >= 3), map(({ heroId }) => new DropItemCommand({ heroId })), );

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COINS

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KAMMYSLIWIEC @Saga() dropCoins = (events$: Observable) => merge( events$.pipe(ofType(HeroSlayedDragonEvent)), events$.pipe(ofType(HeroFoundItemEvent)), ).pipe( mergeMap(({ heroId }) => Math.random() >= 0.3 ? empty() : of(new DropCoinsCommand(heroId)), ), );

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KAMMYSLIWIEC @Saga() dropCoins = (events$: Observable) => merge( events$.pipe(ofType(HeroSlayedDragonEvent)), events$.pipe(ofType(HeroFoundItemEvent)), ).pipe( mergeMap(({ heroId }) => Math.random() >= 0.3 ? empty() : of(new DropCoinsCommand(heroId)), ), );

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KAMMYSLIWIEC COMMAND COMMAND
 HANDLER EVENT EVENT EVENT EVENT
 HANDLER EVENT
 HANDLER EVENT
 HANDLER SAGAS

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KAMMYSLIWIEC OPEN SOURCE

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KAMMYSLIWIEC

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KAMMYSLIWIEC WWW.TRILON.IO

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KAMMYSLIWIEC THANK
 YOU @KAMMYSLIWIEC