How Camunda 8 Stores Workflow State (Zeebe Internals Explained)

Zeebe Architecture Overview

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✍️ Introduction

If you’re coming from Camunda 7 (DB-based engine), understanding how Camunda 8 (Zeebe) stores workflow state is a game changer.

Instead of storing process state in a relational database, Zeebe uses a distributed event-driven architecture — making it:

• ⚡ Highly scalable
• 🔁 Fault tolerant
• 🚀 Extremely fast

👉 Let’s break this down in a simple, practical way.

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🧩 1. Core Idea: Event-Sourced State

In Zeebe:

❌ No central database
✅ Workflow state = event stream (log of events)

Every action in a workflow becomes an event:

• Process started
• Task activated
• Variable updated
• Task completed

These events are written sequentially to a log.

📌 This is similar to Kafka-style architecture.

👉 Zeebe stores state as event streams on disk across brokers

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🖼️ Event Stream Concept

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⚙️ 2. How State is Actually Stored

Let’s simplify:

🧱 Step-by-step

1. Client sends command
   → via Gateway (REST/gRPC)
2. Gateway routes to a Broker

3. Broker writes an event:

   PROCESS_INSTANCE_CREATED
   TASK_ACTIVATED
   VARIABLE_UPDATED
   

4. Event is:
   • Stored in log (append-only)
   • Replicated to other brokers
5. Internal state is rebuilt from events

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🧠 Important Concept

👉 State = Result of replaying events

Not stored directly like:

status = COMPLETED

Instead:

EVENT 1 → started
EVENT 2 → task1 completed
EVENT 3 → task2 completed

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🧩 3. Role of Brokers & Partitions

🖼️ Brokers & Partitions

Zeebe is distributed by design:

• Multiple brokers
• Each broker holds partitions
• Each partition has:
  • Leader
  • Followers (replication)

👉 This ensures:

• No data loss
• High availability
• Horizontal scaling

📌 Data is replicated across brokers, eliminating single point of failure

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🔄 4. State Reconstruction (Replay Mechanism)

If a broker crashes:

1. It restarts
2. Reads event log
3. Rebuilds workflow state

👉 This is called state replay

📌 That’s why:

• No DB recovery needed
• No complex transactions
• Faster recovery

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⚡ 5. Why This is Better than Camunda 7

Feature	Camunda 7	Camunda 8 (Zeebe)
Storage	RDBMS	Event log
Scaling	Vertical	Horizontal
State	Stored in tables	Reconstructed
Bottleneck	DB	Distributed
Performance	Moderate	High throughput

📌 Zeebe avoids DB bottlenecks by using distributed logs

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🧠 6. Internal Components That Handle State

🔹 Gateway

• Entry point
• Routes requests

🔹 Broker

• Stores event log
• Executes workflow logic

🔹 Exporters

• Push data to:
  • Elasticsearch
  • Monitoring tools

🔹 Clients

• Interact via API
• Execute business logic

📌 Zeebe separates orchestration from business logic

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🖼️ End-to-End Flow

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🚀 7. Real-Life Example

Order Processing Workflow

1. Order Created → Event
2. Payment Task → Event
3. Payment Completed → Event
4. Shipping Triggered → Event

👉 Entire workflow = sequence of events

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💡 Key Takeaways

• ✅ Zeebe stores workflow state as event streams
• ✅ No traditional database dependency
• ✅ State is rebuilt, not stored
• ✅ Distributed architecture = scalability
• ✅ Perfect for microservices orchestration

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📚 Recommended Articles 

👉 Camunda + Database Design (History tables, optimization, scaling)
👉 Securing Workflows in Camunda 8 (Auth & Roles)
👉 Java + Spring Security (Authentication & Authorization

French Version:  https://shikhanirankari.blogspot.com/2026/04/comment-camunda-stocke-letat-des.html

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