Using the Humble Object Pattern in a real-world example: Banking Application

Introduction

In the world of banking, software systems must be able to handle large amounts of data and complex financial transactions. Testing such systems can be difficult when components have a high degree of coupling with their environment. The Humble Object Pattern is a design pattern that can help address this problem by separating the core logic of a component from its dependencies.

The Humble Object Pattern:

The Humble Object Pattern involves separating the core business logic of a component from its dependencies. The core logic is extracted into a separate, "humble" object, which is responsible only for the processing of data and making computations. The humble object is then wrapped by another object that deals with the external dependencies and interactions with the environment.

Applying the Humble Object Pattern in a Banking Application:

Let's consider a banking application that needs to handle deposits and withdrawals from accounts. The core business logic of the application involves computing the balance of an account based on the transactions that have been made. However, the application also needs to interact with external systems, such as databases and payment gateways, to perform these transactions.

To apply the Humble Object Pattern, we can create a BankAccount class that contains the core business logic of the application. This class is responsible for computing the balance of an account based on the transactions that have been made. It takes a list of transactions as input and returns the current balance of the account.

Next, we can create an AccountService class that wraps the BankAccount class and deals with the external dependencies and interactions with the environment. This class is responsible for performing the transactions and interacting with external systems, such as databases and payment gateways. It takes a BankAccount object and a TransactionService object as input and exposes a simple interface for performing transactions and retrieving the balance of an account.

Benefits of the Humble Object Pattern in a Banking Application:

The Humble Object Pattern provides several benefits for a banking application, including:

1. Increased testability: By separating the corebusiness logic from its dependencies, the pattern makes it easier to test the application. The BankAccount class can be tested independently of the AccountService class, as it has no external dependencies. This allows for more focused and targeted testing, making it easier to identify and isolate issues.
2. Easier maintenance: By separating the core business logic of the application from its dependencies, the pattern makes it easier to modify and update the application without affecting other parts of the system. For example, if the database schema changes, the AccountService class can be updated without needing to modify the BankAccount class.
3. Better separation of concerns: By separating the core business logic from its dependencies, the pattern promotes a better separation of concerns in the application. Each class is responsible for a single task, making the code easier to understand and modify.

Real-World:

Let's consider a real-world example of how the Humble Object Pattern can be applied in a banking application. Suppose a bank is developing a mobile app that allows users to perform transactions on their accounts. The app needs to interact with external systems, such as a database and a payment gateway, to perform these transactions.

To apply the Humble Object Pattern, the bank can create a BankAccount class that contains the core business logic of the application. This class is responsible for computing the balance of an account based on the transactions that have been made. It takes a list of transactions as input and returns the current balance of the account, just like the previous example.

Next, the bank can create an AccountService class that wraps the BankAccount class and deals with the external dependencies and interactions with the environment. This class is responsible for performing the transactions and interacting with external systems, such as databases and payment gateways, just like the previous example.

The AccountService class can be used in the mobile app to perform transactions on the user's account. The app can call the Deposit and Withdraw methods to perform transactions, and the GetBalance method to retrieve the current balance of the account. The app can also display the transaction history to the user by calling the GetTransactionHistory method of the TransactionService class.

Conclusion:

In this article, we have explored how the Humble Object Pattern can be applied to a banking application using C#. We have demonstrated how the pattern can be used to separate the core business logic of the application from its dependencies, making it easier to test and maintain. The example code provided shows how the BankAccount and AccountService classes can be used to implement the pattern in practice, and the real-world example illustrates how the pattern can be applied to a mobile app for banking transactions.