Camunda BPM Gateways

 🚀 Introduction

In BPMN (Business Process Model and Notation), gateways control the decision-making and synchronization within a process flow.

Camunda BPM implements these gateways exactly according to the BPMN 2.0 specification.

In this blog, we will learn:

✔ What each gateway means
✔ When to use which type
✔ How Camunda executes them internally
✔ Real-world workflow examples

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🧩 What Are Gateways in BPMN?

Gateways are decision and routing points.
They determine how the process should continue, based on:

• Conditions

• Parallel paths

• External events

• Complex logic

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🔀 Types of Gateways in Camunda BPM

There are 5 major BPMN gateways:

Gateway	Icon	Use Case
Exclusive Gateway (XOR)	❌	Only one path is taken
Inclusive Gateway (OR)	🟢	One or more paths can be taken
Parallel Gateway (AND)	➕	All paths start in parallel
Event-Based Gateway	⏳	Waits for external events
Complex Gateway	⚙️	Advanced logic / conditions

Let’s understand each one.

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1️⃣ Exclusive Gateway (XOR) – “Pick One Path” ❌

The Exclusive Gateway chooses only one outgoing sequence flow.

✔ When to use:

• Only one condition must be true

• Exactly one route must be followed

• Typical for: approvals, validations, flow branching

► Example:

Order Received
       ↓
Check Order Amount
   ↓      ↓
< 500   >= 500




✔ Camunda Behavior:

• Evaluates conditions in order

• First matching condition wins

• Optional default path available

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2️⃣ Inclusive Gateway (OR) – “Pick One or Many” 🟢

This gateway allows one OR multiple branches to execute.

✔ When to use:

• Multiple conditions can be true

• Some rules overlap

• Example: validation + email notification combinations

► Example:

Check Document
   ↓     ↓     ↓
Valid? Missing Fields? Needs Review?

Camunda triggers all applicable paths.

✔ Camunda Behavior:

• Merges paths using synchronization

• Completes only when all active paths return

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3️⃣ Parallel Gateway (AND) – “Run All Paths” ➕

Parallel gateways launch all branches simultaneously.

✔ When to use:

• Execute tasks in parallel

• Independent activities

• Example:

  • Send email

  • Generate invoice

  • Create user profile

► Example:

Start
  ↓
Parallel Gateway
 ↓ ↓ ↓
A  B  C (parallel tasks)

✔ Camunda Behavior:

• No condition checks

• All outgoing flows execute

• At join, all flows must complete

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4️⃣ Event-Based Gateway – “Wait for External Events” ⏳

This gateway waits for events, not expressions or conditions.

✔ When to use:

• Waiting for user response

• Waiting for external signals/messages

• Handling timeouts

► Example:

Wait For:
1️⃣ Message from System A  
2️⃣ Timer 5 minutes  
3️⃣ User clicks cancel  

First event that occurs decides the flow.

✔ Camunda Behavior:

• Creates event subscriptions

• First event that triggers wins

• All other events are cancelled

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5️⃣ Complex Gateway – “Advanced Logic” ⚙️

Used for special synchronization logic.

✔ When to use:

• Custom join conditions

• Dynamic number of incoming paths

• Complex business rules

► Example:

“A step continues after ANY TWO of the incoming tasks are complete.”

✔ Camunda Behavior:

• Evaluates complex expressions

• Rarely used but powerful for advanced workflows

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📊 Summary Table – Camunda Gateways

Gateway	Trigger Rule	Execution
❌ Exclusive (XOR)	Pick 1 path	Only first true
🟢 Inclusive (OR)	Pick 1 or many	Waits for all active paths
➕ Parallel (AND)	All paths	All must complete
⏳ Event-Based	Wait for event	First event wins
⚙ Complex	Custom logic	Controlled merging

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🧠 Real-World Examples

🧾 Invoice Approval Process

• XOR → Validate invoice (correct/incorrect)

• OR → Notify multiple teams depending on rules

• AND → Generate PDF + Send email + Log entry

🚀 Microservices Workflow

• AND → Run independent services in parallel

• Event-Based → Wait for callback event or timeout

🏦 Banking KYC Workflow

• OR → Trigger missing documents checks

• XOR → Route based on risk level

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🔧 How Camunda Executes Gateways Internally

✔ Exclusive / Inclusive:

• Conditions defined in the sequence flow

• Camunda parses FEEL-like or JUEL expressions

✔ Parallel:

• No condition evaluation

• Creates concurrent tokens

✔ Event-Based:

• Registers event subscriptions in DB

• Chooses whichever occurs first

✔ Complex:

• Uses tokens + custom conditions

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🎯 Conclusion

Gateways are the decision-makers of Camunda BPM workflows:

• ❌ Exclusive → choose only one  

• 🟢 Inclusive → choose one or many

• ➕ Parallel → run everything

• ⏳ Event-Based → wait for events

• ⚙ Complex → advanced routing

Understanding when and how to use each gateway helps you build clean, scalable, and robust workflows in Camunda 7.

Gateways make BPMN powerful — they control decision-making, flow routing, synchronization, and event handling.

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