Event-Driven Serverless: Choreography vs Orchestration सोप्या भाषेत

By Ravindra Bagale, trainer · LinkedIn · Last updated: 2 November 2026

1. रोजचे उदाहरण: लग्नाचे cues

ढोल = choreography. Pheras sequence = orchestration. Diego (São Paulo) order-paid: inventory/email react; refund saga = workflow.

Deep chapters: EventBridge, Step Functions, SQS/SNS.

2. फरक का महत्त्वाचा

हे का लागतं?

सगळं choreography = 2 AM गोंधळ. सगळं orchestration = प्रत्येक notify = state machine. Mix.

हे काय आहे?

Choreography: events + subscribers. Orchestration: workflow engine.

3. Vertical comparison

4. Decision table

5. Order-paid दोन्ही मार्गांनी

कसं करायचं (step by step)

Choreography sketch

1. OrderPaid event.
2. Inventory consumer.
3. Email consumer.
4. Analytics.
5. Per-consumer DLQ.

Orchestration sketch

1. StartExecution.
2. Tasks.
3. Compensate.
4. Support ARN.

Event buses

aws events list-event-buses --region ap-south-1

अर्थ: Default bus; custom = isolate.

State machines

aws stepfunctions list-state-machines --region ap-south-1 --query 'stateMachines[].{N:name,A:stateMachineArn}'

अर्थ: Existing SFN बघा.

6. Spaghetti events

7. Mini-examples

Python choose

def mode(needs_saga, many_side_effects, need_timeline):
    if needs_saga or need_timeline:
        return "orchestrate"
    if many_side_effects:
        return "choreograph"
    return "either"
print(mode(True, True, False))
print(mode(False, True, False))

Output: orchestrate/choreograph. अर्थ: saga/timeline → SFN.

Rule shape

{
  "source": ["shop.orders"],
  "detail-type": ["OrderPaid"],
  "detail": {"currency": ["INR", "BRL"]}
}

अर्थ: early filter = कमी noise.

8. Lab: दोन्ही designs

Org block नसेल तर ap-south-1 (Mumbai). आधी budget alert.

कसं करायचं (step by step)

1. Choreography draw.
2. Orchestration + compensate.
3. Rules count.
4. SFN preview.
5. Refunds choice.

Cleanup (billing थांबवा)

1. Cleanup if created.
2. SFN delete.

9. Hybrid

Money path = orchestrate. Notify = choreograph. Fatima (Casablanca) तसेच.

10. Commands

Put events

aws events put-events --region ap-south-1 --entries '[{
  "Source":"shop.orders","DetailType":"OrderPaid",
  "Detail":"{"orderId":"o-1","currency":"INR"}"}]'

अर्थ: Sandbox only.

Describe SFN

aws stepfunctions describe-state-machine --state-machine-arn $ARN --region ap-south-1 --query 'definition' --output text | head

अर्थ: Change आधी definition.

11. एकाच pattern — वेगवेगळ्या industries

• Fintech (Aisha, Lagos): payment webhooks → SQS → Lambda.
• Ecommerce (Rohan, Pune): checkout API; inventory SNS fan-out.
• Healthcare (Mei, Singapore): SNS SMS; PHI + fine-grained IAM.
• EdTech (Diego, São Paulo): EventBridge nightly cleanup.
• Logistics (Fatima, Casablanca): EventBridge + saga.
• Media (Kenji, Osaka): S3 → Lambda thumbs + fan-out.
• SaaS (Priya, Bengaluru): Cognito + per-tenant partition.
• Gov (Omar, Amman): strangler fig per form route.

12. Troubleshooting checklist

1. Region confirm करा.
2. CloudWatch Logs + request id.
3. Execution role permissions.
4. DLQ + oldest message age.
5. curl -v + CORS.
6. SFN event history.
7. Linked chapter पुन्हा वाचा.
8. Cost: concurrency/retries.

13. सामान्य errors आणि fixes

प्रत्येक row = खरी चूक. Panic करण्याआधी fix वाचा.

14. FAQ

15. Interview Q&A (Beginner / Mid / Senior + MNC)

16. Tips — English, मराठी आणि हिंदी

17. Correlation ids

प्रत्येक event: orderId + eventId. Support एक id paste करून story.

{"eventId":"e-9f","orderId":"o-1","type":"OrderPaid","currency":"AED","version":1}

18. Custom bus कधी

• Domain isolation.
• Archive policy.
• IAM per team.

19. SFN cheat sheet

20. Architecture decision checklist

1. User journey 5 bullets, no AWS names.
2. Sync vs async mark.
3. Failure mode.
4. Idempotency key.
5. Data from access patterns.
6. Cost 1x and 10x.
7. Quotas ap-south-1.
8. Auth decision.
9. On-call + alarm.
10. Deep chapter link.
11. मग console/IaC.

21. Copy-paste quick commands

# Region and identity
aws configure get region
aws sts get-caller-identity

# Lambda landscape
aws lambda list-functions --region ap-south-1 --max-items 20 \
  --query 'Functions[].{N:FunctionName,R:Runtime,T:Timeout,M:MemorySize}' --output table
aws lambda get-account-settings --region ap-south-1

# API Gateway (HTTP APIs)
aws apigatewayv2 get-apis --region ap-south-1 --query 'Items[].{N:Name,Id:ApiId,Ep:ProtocolType}' --output table

# Queues and topics
aws sqs list-queues --region ap-south-1
aws sns list-topics --region ap-south-1 --query 'Topics[].TopicArn'

# Event buses and state machines
aws events list-event-buses --region ap-south-1
aws stepfunctions list-state-machines --region ap-south-1 --query 'stateMachines[].name'

# DynamoDB tables (names only)
aws dynamodb list-tables --region ap-south-1

Sandbox + read-only IAM.

22. अजून industry आणि stack stories

• Fintech Lagos: webhook → SQS → idempotent ledger.
• Ecommerce Pune: throttle + fan-out.
• Healthcare SG: SNS + PHI IAM.
• EdTech: EventBridge cleanup.
• Logistics: bus + saga.
• Media: avoid recursive S3.
• SaaS: tenant partition.
• Gov: strangler peel.
• Startup: Function URL → HTTP API.
• Retail: FIFO vs Standard.

• Python: thin handlers.
• Node: async/await.
• Java: SnapStart.
• .NET: package size.
• Go: static binary.
• PHP: hybrid.

23. Glossary

24. Practice: मोठ्याने explain

1. 60s: choreography vs orchestration गोष्ट.
2. 60s: sync vs async checkout.
3. 60s: Lambda नको कधी.
4. 60s: DLQ + idempotency.
5. Record ×2.

25. Safe lab hygiene

• Tag owner+expiry.
• Budget alarm आधी.
• Read-only first.
• Cleanup.
• No secrets in env/screenshots.
• No provisioned on hello.

26. या chapter च्या links

• Compute: Lambda.
• HTTP: API Gateway.
• Data: DynamoDB.
• Messaging: SQS/SNS.
• Events: EventBridge.
• Workflows: Step Functions.
• build-* projects link.

27. Myths

28. Serverless error budget

Checkout error budget 0.1% असेल तर aggressive retries email duplicates देऊन budget जाळू शकतात. Money SLO ≠ notify SLO.

1. दोन SLOs.
2. Money retries bounded.
3. Notify best-effort.
4. Money page; notify ticket.

29. Regional notes (ap-south-1)

• Labs Mumbai.
• Feature availability.
• Data residency.
• Latency India.

30. Naming conventions

# Suggested prefixes
# Lambda:  pay-intake-prod, pay-worker-prod
# SQS:     pay-orders.fifo / pay-orders-dlq
# SNS:     pay-order-events
# EB bus:  pay.domain
# SFN:     pay-refund-saga
# DDB:     pay-orders-prod

env + domain नावात ठेवा. CloudWatch grep सोपा.

31. Pre-mortems

1. Double charge headline.
2. DLQ drain plan.
3. Cognito outage mode.
4. Runbook.

32. Currency / locale

Currencies आणि names rotate करा — global mental model.

उजळणी, मुलाखत आणि तुलना cards

हा lesson काही मिनिटांत revise करा. Cards phone वर save करा किंवा PNG download करा. प्रत्येक card वरचा QR हा lesson उघडतो.

अजून cards: Ravi Sir's Cards.