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ENABLING A RESILIENT ORDER MANAGEMENT
Jochen Bürkle, 20.10.2022

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MediaMarktSaturn - Data In Motion Tour
About me
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Jochen Bürkle
6 years of experience in automotive and telecom, 12 years in retail
Focus: Java, Kotlin, Microservices, Cloud based architectures
Voluntary secretary in the Java User Group Ingolstadt e.V. https://jug-in.bayern
linkedin.com/in/jochen-bürkle-ab694720
buerkle@mediamarktsaturn.com
Principal Engineer in Order Management domain at MediaMarktSaturn Technology

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MediaMarktSaturn - Data In Motion Tour
Numbers and Figures MediaMarktSaturn
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• Fiscal year 2020/21
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THERE
OF
21.4 BN. EUROS REVENUE
6.9 BN. EUROS ONLINE
WE ARE THE #1
IN EUROPE
> 52,000
EMPLOYEES
2.4 BN.
CUSTOMER
CONTACTS
PER YEAR
ONLINE %
>1,000 STORES
13 COUNTRIES
IN
REVENUE
13.7%
20.2%
32.5%
2020/21
2019/20
2018/19
https://www.ceconomy.de/en/company/facts-and-figures/

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MediaMarktSaturn - Data In Motion Tour
Origins and Structures
› MediaMarktSaturn has more than 40 years of history
› MediaMarktSaturn is currently present in 13 countries
› Software stack historically country specific, rate of individuality is varying
› Since the 1990s: Self developed GMS as Order Management System
› Entering seriously online business in 2011
› First reusing GMS system
› Then introduction of dedicated Order Management systems
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MediaMarktSaturn - Data In Motion Tour
Order Management History
› Dedicated instances of in-house developed Goods Management System for Online
› A standard Order Management system with a „flavor“
› A country developed and introduced another in-house Order Management system
Now:
› A big blue standard Order Management system to replace them all (yet not at a time)
Common features of these:
› Systems mostly monolithic, scaling mostly vertical
› Big Integration efforts
› Different integration styles
› Different APIs
› No unified way to expose order data
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MediaMarktSaturn - Data In Motion Tour
IT Strategy Change 2018 – One IT
› Cloud Strategy – Google Cloud
› Move everything to the cloud or build it cloud native
› Usage of managed services – „Use managed things, don‘t manage things“
› Transforming into a product organization
› Each product exposes a Restful API, API first
› New Checkout process
› New web, crosschannel checkout, order create service
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Web Shop
Shopping
Basket
Order
Creation
Service
OMS B
OMS C
REST/https REST/https
REST/https
JMS
Order Management Domain

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MediaMarktSaturn - Data In Motion Tour
Resilience in IT
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„Capability of IT systems to react robustly on interruption or outage of particular components
and
to continue providing the required services to the customer / consumer / client.“

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MediaMarktSaturn - Data In Motion Tour
Building a Resilient Order API Service
› Requirements
› High availabilty and resilience
› Creating an Order Management API Service as master system, exposing Data in unified schema
› Integration of all Backend Order Management Systems as „Order Engines“
› Cloud Native
› Built in Google Cloud Kubernetes Engine
› Terraform Modules defined infrastructure
› GitOps based deployment approach
› Managed Services
› Safe and lean software stack for the JVM
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MediaMarktSaturn - Data In Motion Tour
Lean Service Stack
› JVM based – Kotlin
› Less but more concise code
› Much better nullpointer safety
› Full Java (library) compatibility
› Library based – no heavyweight frameworks
› We are not shipping nor starting what we do not need
› Microservices in the true sense of the word
› One concern per service
Startup times below 5 seconds
Initial memory footprints below 150 MiB
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MediaMarktSaturn - Data In Motion Tour
Event based architecture with a Kafka managed service
Get all together: Event based cloud service mesh „Customer Order Services (COS)“ in Kubernetes
› Resilience through decoupling: Confluent Kafka managed service
› Kafka buffers the events while keeping the message ordering
› Possibility of replays
› Exactly once semantics
› Event based architecture as basis for Multi-OMS integration
› Common event schema used for all front- and backends
› Efforts mainly data structure mapping
› Events and internal COS APIs built on Protobuf
› Advantages in message structuring over Avro
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MediaMarktSaturn - Data In Motion Tour
COS Event based architecture
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API
Consumers
(search&load)
API
Consumers
(search&load)
O
Confluent
Kafka
Order Master DB
<MongoDB>
Customer Order
API Service
ERP
Client Svc
OMS B
Export Svc
Invoicing
Client Svc
Customer
Notification Client
FSP via ERP
OMS C
API
Consumers
(search&load)
ERP
OMS C
Invoicing
Customer
Comm.
Order Creation
Service
OMS B
Digital Article
(POSA) Client
POSA
Service
XCCB
Create
Fulfillment
Modify SO
Digital
Fulfilment
Sales Order
OMS A
Export Svc
APIX
<Tibco
EMS>
Despatch Advice
Reserv. SO
Fulfillments
Customer Not.
Order Creation
OrderShipment
Activation
COS Platform
Order
Publish/Storage
Svc
OrderCreated
OrderCreated
OrderCreated
DigitalArticle
Activated
FulfillmentCreated
FulfillmentCreated
ShipmentCreated
ShipmentCreated
ItemReplaced
FulfillmentCreated
<All Events>
FulfillmentCreated
FulfillmentCreated
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MediaMarktSaturn - Data In Motion Tour
Creating visibility - COSMOS
› Binary Protobuf messages have a limited visibilty as consequence
› Solution: Streams application with generic record transformation, saved to MongoDB
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MongoDB Atlas
DynamicMessage
JsonFormat
Web formatting
COSMOS Service
…

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MediaMarktSaturn - Data In Motion Tour
Outlook – Enterprise scale domain events
› Need to overcome synchronous blocking issue and P2P integrations in pure Restful API approach
› MediaMarktSaturn started to introduce domain events
› Introduction of 2 flavors of event communication
› Notifications – No data payload, just event typ and key/reference information
› Data Streaming – Message contains complete data objects
› Events based on CNCF‘s Cloud Events: https://cloudevents.io/
› Messaging infrastructure is Google Pub/Sub
› Vendor limitation and proprietary implementation
› Peer to peer connecting and decentralized access grant
› Very limited retention: 7 days
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MediaMarktSaturn - Data In Motion Tour
Why Confluent?
› We don‘t want to manage a Kafka, we want to build and run an order management platform
› It was available on the GCP marketplace (back in 2018)
› Additional features like Schema Registry, Connectors, …
› We need to have most professional support and quick solutions when necessary
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15.
Vielen
Dank
https://www.mediamarktsaturn.com