If Event Subscriptions are the “listeners,” then Event Publishers are the “speakers.” They are what raise (trigger) events inside Business Central so other code can react. This blog explains everything from basics to practical use—with simple examples.

What is an Event Publisher?

An Event Publisher is a method in AL that raises an event using attributes like:

• [IntegrationEvent]
• [BusinessEvent]

It allows other developers (or your own extension) to subscribe and extend behavior.

Why Event Publishers Are Important

Without publishers:

• No extension points
• Hard-coded logic
• Difficult upgrades

With publishers:

• Clean extensibility
• Upgrade-safe design
• Loose coupling
• Reusable architecture

Simple Analogy

Think of a YouTube Live Stream:

• Publisher = Person streaming
• Subscribers = Viewers watching
• Publisher sends event → Subscribers react

 Types of Event Publishers

 1. Integration Events (Most Common)

Used for customization inside Business Central

[IntegrationEvent(IncludeSender : Boolean, GlobalVarAccess : Boolean)]

• Flexible
• Can expose internal logic

2. Business Events

Used for external integrations

[BusinessEvent(false)]

• Stable
• Used in Power Automate / APIs

Basic Syntax of Event Publisher

[IntegrationEvent(false, false)]
procedure OnAfterCustomerCreated(Customer: Record Customer)
begin
end;

This defines an event—but does NOT run automatically. You must call it manually

Calling (Raising) the Event

procedure CreateCustomer()
var
    Customer: Record Customer;
begin
    // Insert logic here
    OnAfterCustomerCreated (Customer); // Event triggered
end;

Complete Example (Publisher + Subscriber)

 Step 1: Create Publisher

codeunit 50100 CustomerPublisher
{
    [IntegrationEvent(false, false)]
    procedure OnAfterCustomerCreated(Customer: Record Customer)
    begin
    end;
    procedure CreateCustomer()
    var
        Customer: Record Customer;
    begin
        Customer.Init();
        Customer.Name := 'Test Customer';
        Customer.Insert();
        OnAfterCustomerCreated(Customer); // Raise event
    end;
}

Step 2: Create Subscriber

codeunit 50101 CustomerSubscriber
{
    [EventSubscriber(ObjectType::Codeunit, Codeunit::CustomerPublisher, 'OnAfterCustomerCreated', '', false, false)]
    local procedure HandleCustomerCreated(Customer: Record Customer)
    begin
        Message('Customer Created: %1', Customer.Name);
    end;
}

Key Concepts You Must Understand

1. Publisher ≠ Subscriber

Publisher	Subscriber
Raises event	Listens to event
Defines method	Implements reaction

2. Event Does Nothing Alone

If no subscriber exists → nothing happens
Publisher just provides a hook

3. Multiple Subscribers Allowed

One event → Many subscribers
Each runs independently

Parameters Explained

[IntegrationEvent (false, false)]

Parameter	Meaning
IncludeSender	Access to publisher object
GlobalVarAccess	Access global variables

Real-World Use Cases

 1. After Customer Creation

• Send email
• Log activity
• Sync to Azure SQL

 2. Sales Posting

• Custom validation
• External API call
• Audit tracking

3. Workflow Triggers

• Notify approval system
• Trigger Power Automate

Common Beginner Mistakes

❌ Forgetting to call the event
✔ Always trigger manually

❌ Putting logic inside publisher
✔ Keep it clean—logic goes in subscribers

❌ Too many parameters
✔ Keep events simple

Best Practices

• Use clear naming: OnBefore…, OnAfter…
• Keep publishers lightweight
• Document your events
• Avoid breaking changes in published events

Quick Summary

• Event Publisher = raises event
• Defined using [IntegrationEvent] or [BusinessEvent]
• Must be called manually
• Enables clean extension of logic
• Works with Event Subscribers

Final Thoughts

Mastering Event Publishers means you can:

• Build scalable extensions
• Avoid modifying base code
• Design enterprise-grade solutions

It’s one of the most powerful patterns in Business Central development.