This new capability enables one-to-many message delivery from a single OCI Queue, while preserving the pull-based consumption model customers rely on.

With fan-out and filtering, you can now:

  • Deliver a single message to multiple independent consumers
  • Apply selective filtering per consumer group
  • Maintain deterministic delivery semantics
  • Preserve backward compatibility
  • Scale high-throughput application-to-application (A2A) workloads

Why This Matters

In event-driven systems, you often need to:

  • Send one event to multiple microservices
  • Route specific events to specific services
  • Avoid duplicating producers
  • Preserve message durability and visibility controls

Without native fan-out, customers typically:

  • Create duplicate queues
  • Implement routing logic in application code
  • Build custom dispatchers
  • Introduce operational overhead

OCI Queue Fan-out with Filtering eliminates this complexity.

What’s New?

Consumer Groups

Consumer groups are now first-class OCI Queue resources that enable fan-out.

Each consumer group:

  • Represents an independent pull-based consumption path
  • Can optionally define a filter expression
  • Maintains independent visibility and delivery attempts
  • Can be enabled or disabled
  • Is secured using IAM

When fan-out is enabled, messages published to a queue are evaluated against all consumer groups.

Primary Consumer Group (Backward Compatibility)

When you enable fan-out on a queue:

  • A Primary Consumer Group is automatically created
  • It receives all messages
  • It cannot be deleted
  • It does not support filters
  • It can be disabled if needed

This ensures existing applications continue to work without any changes.

Message Filtering

You can now apply SQL-like filtering expressions to consumer groups.

Filtering is evaluated:

  • At publish time
  • Based on message attributes (not message body)
  • Using logical operators and comparison operators

Supported filtering includes:

  • Key presence: :region
  • String equality: :type = "order"
  • Numeric comparisons: :age > 40
  • Logical operators: AND, OR, NOT
  • Functions: hasPrefix(), hasSuffix()

If no consumer group matches a message:

  • The message is dropped
  • A metric is emitted
  • The message cannot be retrieved later

This ensures deterministic and predictable behavior.

How It Works

Under the hood:

  1. A message is published to the queue.
  2. The service evaluates all consumer group filters.
  3. The message is logically delivered to matching consumer groups.
  4. The payload is stored once and reference-counted.
  5. The message is deleted only after all matching groups consume it.

This design:

  • Avoids message duplication
  • Preserves performance
  • Scales cleanly
  • Maintains cost efficiency

Step-by-Step: Enabling Fan-out and Filtering

Below is a walkthrough using the OCI Console.

Step 1: Create a Queue

In the OCI Console:

  1. Navigate to Developer Services → Queues
  2. Click Create Queue
  3. Provide a queue name
  4. Choose configuration (default or custom)
  5. Under Queue capabilities, enable:

Enable consumer groups

This activates the fan-out capability.

Step 2: View the Primary Consumer Group

After the queue is created:

  1. Navigate to the queue
  2. Open the Consumer groups tab

You’ll see:

  • Primary Consumer Group (Active)
  • No filter expression

Step 3: Create a Secondary Consumer Group with Filtering

To enable selective delivery:

  1. Click Add consumer group
  2. Enter a name (for example, “Another Consumer Group”)
  3. Optionally configure DLQ delivery attempts
  4. Add a filter expression

Example:
 
:age > 40

Now you have:

  • Primary Consumer Group (receives all messages)
  • Secondary Consumer Group (receives only messages where age > 40)

Step 4: Send Messages with Attributes

  1. Send a few messages 
  2. Provide message body
  3. Add message attributes

Example:

  • Key: age, Value: 50
  • Key: age, Value: 60
  • Key: age, Value: 30

After sending 3 messages:

  • The Primary Consumer Group receives all 3 messages (as there is no filtering)
  • The filtered consumer group receives 2 messages (because 50 > 40)

Step 5: Observe Message Delivery

When polling messages from:

  • Primary Consumer Group → All messages visible
  • Filtered Consumer Group → Only matching messages visible

Delivery Guarantees and Drop Semantics

It’s important to understand filtering behavior:

  • Filters are evaluated only at publish time.
  • If the Primary Consumer Group is disabled and no other consumer group matches:
    • The message is dropped.
    • A metric is emitted.
    • The message cannot be recovered later.

This ensures predictable, deterministic routing.

IAM and Security

Consumer groups are first-class IAM resources.

You can:

  • Allow specific dynamic groups to consume from specific consumer groups
  • Grant fine-grained access
  • Separate queue administration from fan-out configuration

Example:
 
allow dynamic-group AppConsumers to use queue-pull in compartment MyCompartment where target.consumer-group.id = '<consumer_group_ocid>'

Use Cases

Microservices Routing

Send one event to:

  • Billing
  • Fraud detection
  • Notifications
  • Analytics

Each service consumes independently.

Priority Routing

Route high-priority messages to one service:
 :priority >= 5

Multi-tenant Systems

Use attributes like:
 :tenantId = "tenantA"

Performance Characteristics

  • Pull-based consumption (REST API)
  • Low latency delivery (p90 < 500 ms)
  • Up to 1 MB message size
  • Independent consumer scaling
  • Shared retention across consumer groups

Why This Is Powerful

OCI Queue Fan-out with Filtering combines:

  • The simplicity of queues
  • The flexibility of pub/sub
  • The determinism of pull-based consumption
  • Enterprise-grade IAM control

All without requiring a separate messaging service.

Get Started Today

OCI Queue Fan-out with Filtering (Consumer Groups) is now available.

To try it:

  1. Create a queue
  2. Enable consumer groups
  3. Add filtered consumer groups
  4. Send messages with attributes
  5. Observe selective delivery

Learn more in the OCI Queue documentation. 

We’re excited to see what you build.