Business Rules: Everything you need to know

Nuno Miguel Ferraz
4 min readApr 3, 2024

In software development, business rules play a crucial role in defining how the application should operate to meet the specific objectives and needs of an organization or market. They are decisive guidelines that influence software behaviour, operations, and constraints, shaping the way data is processed and functionalities are executed.

A portable computer, displaying some lines of code.
Photo by James Harrison on Unsplash

What Are Business Rules?

Business rules are precise instructions that define, control, or influence the operational behaviour of a system. They reflect the policies, procedures, and essential conditions for the organization to achieve its objectives, ensuring consistency, efficiency, and compliance in operations.

Common Practical Examples of Business Rules:

  • Conditions for credit approval in financial institutions.
  • Tax calculations and discounts in sales.
  • Access restrictions and authorizations in information systems.

Importance of Business Rules

The precise implementation of business rules is crucial to:

  • Ensure that the application aligns with the company’s objectives and strategies.
  • Improve the quality and consistency of operations.
  • Facilitate adaptation to regulatory and market changes.
  • Automate processes, reducing human errors and increasing efficiency.

Identifying Business Rules

Accurate identification of business rules is an essential step before their implementation. This process typically involves the following steps:

  • Detailed discussions with stakeholders to understand the organization’s objectives, policies, and procedures.
  • Analysis of organizational documents, such as procedure manuals, terms of service, and internal policies.
  • Evaluation of legal and regulatory requirements relevant to the company’s industry sector.
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Exploring Practical Examples

Risk Management in Banks
A business rule can determine the acceptable level of risk for credit approval based on various factors such as the applicant’s credit history, income, and debt-to-income ratio. This helps banks automate part of the credit approval process while staying within defined risk limits.

Dynamic Pricing in Retail
Business rules can be used to adjust product prices in real-time based on factors such as demand, inventory, and competition. This allows retailers to maximize profit margins and respond quickly to market changes.

Implementing Business Rules in Applications

The implementation of business rules can vary considerably, depending on the complexity of the rule and the application architecture. Here are some common approaches:

1. Direct Coding: Direct implementation of business rules in the application code. This approach is simple but can make the code difficult to maintain, especially if the rules change frequently.

Practical example, using Python:

def approve_loan(annual_income, loan_amount):

# Rule 1: Annual income must be at least 3 times the requested loan amount
if annual_income < loan_value * 3:
return False

# Rule 2: The maximum loan amount allowed is R$50,000
if loan_value > 50000:
return False

# If all conditions are met, the loan is approved
return True

# Example of using the function
annual_income = 60000 # Applicant's annual income
loan_value = 15000 # Amount requested for the loan

if approve_loan(annual_income, loan_value):
print("Loan Approved")
else:
print("Loan Denied")

2. Specific Business Rules Modules: Development of dedicated modules or services within the application to manage business rules. This facilitates maintenance and updating of rules without affecting other parts of the code.

3. Business Rules Management Tools: Use of specialized systems that allow dynamic creation, management, and execution of business rules without the need to alter the application source code. These tools offer a user-friendly interface for business users, allowing them to configure or modify rules as needed.

Best Practices

Documentation and Versioning: Maintain clear and up-to-date documentation of business rules, as well as version them to facilitate change management.

Rigorous Testing: Implement automated tests to ensure that business rules are enforced as expected and to identify impacts of any changes in the rules.

Flexibility and Scalability: Design the application to facilitate adjustments to business rules without requiring major interventions in the code.

Photo by Sigmund on Unsplash

The effective implementation of business rules is a complex task that requires careful planning, collaboration between teams, and a commitment to continuous maintenance and evolution. Organizations that can manage their business rules efficiently can not only increase operational efficiency but also gain a competitive advantage by quickly adapting to new market opportunities and challenges.

Thus, understanding and implementing business rules in applications is not just a technical matter, but also a fundamental business strategy. By adopting best practices and appropriate approaches, companies can ensure that their applications not only meet current needs but also evolve and respond to future demands.

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