4 Patterns to Jumpstart your Event-Driven Architecture Journey Hans-Peter Grahsl Developer 🥑 Advocate 1

Who am I ? 2 Developer 🥑 Advocate @ Red Hat based in Graz, Austria 󰎈 open-source enthusiast 5x Confluent Community Catalyst MongoDB Champion since 2020 speaker at dev & tech conferences @hpgrahsl@mastodon.social Hans-Peter Grahsl “I’m passionate about event-driven architectures, distributed stream processing systems and data engineering.”

Agenda 3 What we’ll discuss today ▸ Claim Check Pattern ▸ Content Enricher Pattern ▸ Message Translator Pattern ▸ Outbox Pattern

EDA Terminology 4 … is a way of designing loosely coupled services that respond (in near real-time) based on the sending and receiving of events. 🤔 Event-Driven Architecture (EDA) ?

EDA Terminology 5 Multiple flavours https://martinfowler.com/articles/201701-event-driven.html 1. Event Notification 2. Event-Carried State Transfer 3. Event Sourcing 4. CQRS (selectively combined with the above)

EDA Terminology 6 This talk’s meaning of Event-Driven Architecture https://martinfowler.com/articles/201701-event-driven.html 1. Event Notification 2. Event-Carried State Transfer 3. Event Sourcing 4. CQRS (selectively combined with the above) this talk’s meaning

It’s all about events … 7 EVENTS EVENTS EVERYWHERE

8 One seeks bullets of silver … … but only finds trade-offs.

Agenda 9 Let’s explore the patterns… ▸ Claim Check Pattern ▸ Content Enricher Pattern ▸ Message Translator Pattern ▸ Outbox Pattern

Claim Check Pattern 10 ▸ inherently binary data graphics, documents, audio, video, … ▸ embedded data (e.g. Base64 encoded) in otherwise textual formats (json, xml, …) unnaturally large / unreasonably heavy event payloads Challenge

Claim Check Pattern 11 ▸ offload large (binary) payload into separate storage system ▸ replace actual payload with reference to claim check ▸ use claim check to fetch data when needed at consumer side externalize large event payloads … or parts thereof Claim Check Pattern

Claim Check Pattern 12

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Claim Check Pattern 17

18 Claim Check Pattern

Agenda 19 Let’s explore the patterns… ▸ Claim Check Pattern ▸ Content Enricher Pattern ▸ Message Translator Pattern ▸ Outbox Pattern

Content Enricher Pattern 20 ▸ payloads are lacking additional details ▸ certain consumers need to know more ▸ example: very compact notification events unnaturally small / unreasonably light event payloads Challenge

Content Enricher Pattern 21 ▸ add missing data e.g. include contextual information ▸ do lookups / perform joins against reference data ▸ take reference data to augment original payload increase the utility of sparse event payloads Content Enricher Pattern

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27 Content Enricher Pattern

Agenda 28 Let’s explore the patterns… ▸ Claim Check Pattern ▸ Content Enricher Pattern ▸ Message Translator Pattern ▸ Outbox Pattern

Message Translator Pattern 29 ▸ examples: ･ integrate legacy systems ･ work with proprietary data formats ▸ minimize or at least reduce the contract-related coupling incompatible or inconvenient event payloads Challenge

Message Translator Pattern 30 ▸ perform a wide range of payload modifications: ･ basic field type conversions ･ rename, redact, or mask fields ･ switch format / protocol ･ … ▸ can also be used to build an anti-corruption layer establish compatibility between disparate systems Message Translator Pattern

Message Translator Pattern 31

Message Translator Pattern 32

Message Translator Pattern 33

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37 Message Translator Pattern

Agenda 38 Let’s explore the patterns… ▸ Claim Check Pattern ▸ Content Enricher Pattern ▸ Message Translator Pattern ▸ Outbox Pattern

Outbox Pattern 39 ▸ XA transactions ? potentially unreasonable choice or sometimes not available at all ▸ example: (micro)service updates its own database and sends event(s) to messaging/event streaming infra consistently update data in 2 different systems Challenge

Outbox Pattern 40 ▸ perform single database transaction spanning: ･ update(s) to affected DB tables (“domain data”) ･ update(s) to outbox DB table (“event data”) ▸ setup separate CDC pipeline for outbox table ･ transfer event data to messaging/event streaming infra ▸ consume CDC stream on-demand in near real-time avoid the dual-writes issue Outbox Pattern

Outbox Pattern 41

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46 Outbox Pattern

▸ no silver bullets for event design / communication → only trade-offs ▸ patterns help to deal with implications and cope with trade-offs Wrap Up 47 Summary of discussed EDA patterns Claim Check Pattern Content Enricher Pattern Message Translator Pattern Outbox Pattern

Demo Repository 48 bit.ly/eda-patterns

Upcoming Talk 49 From edge to cloud, creating data pipelines using open-source with Strimzi on Kubernetes. Date: Wednesday, September 27 Time: 4:30 pm Location: Breakout Room 7 Speakers: Chris Cranford, Carles Arnal There will be a raffle with gifts at the end of the session!

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51 https://unsplash.com/photos/DRzYMtae-vA https://pixabay.com/illustrations/night-sky-stars-moon-wolf-garou-4726445/ https://unsplash.com/photos/HTIduwcMMfQ https://unsplash.com/photos/w9rYOScXf6E https://unsplash.com/photos/iar-afB0QQw https://unsplash.com/photos/q65bNe9fW-w https://pixabay.com/photos/video-production-video-movie-film-4223885/ https://pixabay.com/photos/feather-bird-plumage-flying-4380861/ https://unsplash.com/photos/MceA9kSze0U https://pixabay.com/photos/travel-adapter-plug-charging-plug-3320763/ https://unsplash.com/photos/g97bviyFhvQ https://pixabay.com/illustrations/post-office-mailbox-old-yellow-2438804/ https://pixabay.com/photos/post-office-letter-box-mail-box-2455580/ https://pixabay.com/photos/ecommerce-shopping-credit-card-2607114/ in order of appearance Photo Credits