ServiceNow Best Practices: How Business Rules Work: A Guide for ServiceNow Developers

[BillMartin]

Business Rules are one of the most powerful tools in ServiceNow, allowing developers to control and automate business processes by interacting with data before or after records are saved.

Understanding the execution lifecycle of ServiceNow Business Rules is essential for designing efficient and effective automation within your instance.

In this article, we will cover:

1. What Are Business Rules?
2. Types of Business Rules
3. Business Rule Execution Flow
4. Order of Execution
5. Best Practices for Using Business Rules

 

1. What Are ServiceNow Business Rules?

A Business Rule is a server-side script that runs when a record is inserted, updated, deleted, or queried. Unlike Client Scripts that run on the user’s browser, Business Rules operate on the server, making them ideal for complex data processing and ensuring data integrity.

2. Four Types of ServiceNow Business Rules

ServiceNow provides four types of Business Rules based on when they execute:

• Before: Executes before a record is saved to the database
• After: Executes after a record is saved to the database
• Async (Asynchronous): Executes after a record is saved but in a separate process, allowing faster user interaction
• Display: Executes when a record is queried from the database, before it is sent to the client

Each type serves a specific purpose. For example, Before rules are often used for data validation, while After rules handle notifications, logging, or integrations.

3. ServiceNow Business Rule Execution Flow

The lifecycle of Business Rule execution is straightforward but follows specific stages depending on the type. Let’s break down each stage.

Before Insert, Update, or Delete

Before Business Rules execute when an event occurs (e.g., form submission or script action). Use this stage to manipulate field values or validate data before the database is updated.

Database Update

ServiceNow writes the record changes to the database once all Before Business Rules have completed.

After Insert, Update, or Delete

After Business Rules trigger after the record is saved. This is useful for sending notifications or updating related records.

ServiceNow Asynchronous Processing

Async Business Rules run in a separate thread after the record is saved, without delaying the user interaction. This is ideal for long-running operations such as integrations with external systems.

 

Display (On Query)

Display Business Rules are triggered when a record is fetched from the database. They can be used to provide dynamic information to the form or set default field values before the record is displayed.

4. ServiceNow Business Rule Order of Execution

The execution of server-side operations in ServiceNow follows a defined order:

1. Before Business Rules execute first
2. The record is inserted/updated/deleted in the database
3. After Business Rules are executed
4. Any Async Business Rules are queued for background execution
5. Display Business Rules run when a record is queried

Additionally, ServiceNow processes other elements such as:

• Access Control Rules (ACLs) – Checked before records are queried or modified
• Script Includes and Data Policies – Depending on your configuration, these may also influence record updates

 

5. ServiceNow  Best Practices for Using Business Rules

To ensure optimal performance and maintainability, follow these best practices.

Minimize Database Operations
Avoid querying large data sets or performing heavy operations within a single Business Rule.

Use Async Rules for Long-Running Tasks
Offload time-consuming tasks like sending emails or calling APIs to Async Business Rules to avoid slowing down the user experience.

Avoid Overlapping Business Rules
If multiple Business Rules affect the same table and fields, ensure they don’t conflict with each other.

Test with Different Scenarios
Test Business Rules with both valid and edge-case scenarios to ensure data integrity is maintained.

Leverage Current and Previous Objects
Use the current and previous objects to compare and track changes in field values.

 

Conclusion

Business Rules play a vital role in automating processes and enforcing business logic within ServiceNow. By understanding when and how they execute, you can design more efficient and maintainable scripts. Always test thoroughly and follow best practices to ensure your Business Rules function as intended without impacting performance.

Got questions? Share your thoughts and experiences with Business Rules in the comments below!

Would you like to explore more about Business Rules or other topics? Check out my YouTube channel where I dive into ServiceNow development fundamentals!