Aspect-oriented programming: advantages and disadvantages

What is aspect-oriented programming?

Aspect-oriented programming (AOP) is a programming paradigm designed to improve and increase modularity by enabling the separation of cross-cutting concerns. It makes it easier to add code to pre-existing programmes – by extracting code into manageable sections known as ‘aspects’ – without changing the code itself.

Cross-cutting concerns refer to aspects of a programme affecting other concerns that – in both design and implementation – cannot be easily, or cleanly, decomposed from a system. Cross-cutting concerns can cause code duplication (known as ‘scattering’) and critical dependencies between systems (known as ‘tangling’), as concerns can be found across multiple classes and components. Common cross-cutting concerns include transaction processing, security authentication, data validation, caching, format data, error handling, debugging, and logging.

Here is a simplified walk-through of how AOP works in practice:

1. Identify cross-cutting concerns (for example, logging)
2. Define aspects (the modules that encapsulate the concerns)
3. Weaving (use an AspectJ compiler or weaver to combine aspects with main business logic at compile-time, load-time, or run-time)
4. Application of aspects (apply aspects to specific ‘join points’, where functionality is integrated into the programme)
5. Isolation of concerns (which enables modularization).

The AOP framework is supported by a number of popular programming languages and platforms, including Java (and Java Spring Framework/Spring AOP), C#, Python, .NET, Perl, XML, and Ruby.

How is aspect-oriented programming different from object-oriented programming?

Both AOP and object-oriented programming (OOP) are programming paradigms.

The goal of OOP is to organise code into ‘objects’ (instances of classes) that encapsulate data and behaviour. It uses four principles to model real-world entities: encapsulation (binding data), abstraction (using simple classes to represent complexity), inheritance (enabling classes to inherit features of others), and polymorphism (using different objects to reply to one form, and interact with the same interface).

While AOP and OOP focus on different aspects of software development and design – the former on separation of concerns and the latter on data encapsulation and behaviour – they can be used to complement one another.

What are the advantages of AOP?

AOP’s ability to provide declarative enterprise services – such as declarative transaction management/annotations – for a specific software system or organisation has contributed to its popularity and widespread use. It also allows users to implement custom elements and add additional functionalities and features that were not initially present in the software.

In addition, aspect-oriented software development provides a number of other strategic advantages:

• Modularity. Improvements to code modularity make everything simpler to understand. AOP modularises and separates cross-cutting concerns from core business logic, allowing programmers and developers to handle concerns separately.
• Maintainability. AOP makes it possible to modify or update specific code functionalities – without affecting the wider source code – making software changes more manageable for programmers and developers. It also helps to reduce undesirable or unintended side effects.
• Code reusability. The aspects that are inherent in AOP encapsulate common functionalities and, therefore, promote the reuse of code across different parts of the application.
• Centralised management. AOP makes it easier to implement modifications and changes uniformly across the entire application and, as a result, manage cross-cutting concerns such as transactions and security.
• Readability. Isolating and specifying non-functional requirements improves the readability of central business logic. As such, software engineers can focus on core functionality, free from the distractions of unrelated concerns.
• Scalability. As the codebase grows, the effective management of concerns becomes more important, as well as more complex. AOP supports a cleaner, more organised code structure – which, in turn, supports scalability.
• Better testing functionality. Concerns that have been separated/isolated make it much easier to conduct independent testing. This is useful in terms of promoting better overall software quality and implementing a more effective testing methodology and strategy.

What are the disadvantages of AOP?

While there are many benefits to using the AOP framework, it’s not perfect. As a result, computer programmers, engineers and developers should take time to understand whether AOP aligns well with the specific characteristics and requirements of a particular software program or project.

Some of the disadvantages of AOP include:

• Issues with debugging. Debugging can become more of a challenge. Aspects applied at different points in the programme can affect the flow of control and increase the level of complexity, making it more difficult to identify issues.
• Complexity. Codebases can suffer from greater levels of complexity as more aspects interact with the central business logic. This creates challenges for developers who may not be as comfortable, or familiar, working with AOP frameworks. There are also knock-on effects for testing; additional work may be required to ensure that isolated aspects behave as intended.
• Portability. Portability between different platforms, applications and programming languages may cause issues. As such, AOP can limit the capacity to reuse code in diverse environments.
• Support systems. Integrated development environments (IDE) and tooling may be limited in range when it comes to AOP frameworks. In contrast to OOP, which benefits from a more extensive range of tooling support, AOP can encounter issues working with certain aspects in certain environments.

Moderating the application of AOP principles, and using them responsibly, helps to mitigate some of these potential downsides.

Excel in software development and engineering roles with a specialist master’s degree

Explore the in-demand and highly practical science of programming and software systems with North Wales Management School’s online MSc Computer Science with Software Engineering programme.

You don’t need a background in computer science or software engineering to join our highly flexible, 100% online master’s and gain the skills to succeed in this exciting industry. Designed with the real-world needs of modern business in mind, you’ll develop an acute understanding of the principles underpinning computer science and software development – from network design to web technologies. Engaging modules will introduce you to the fundamentals of mobile application development, systems engineering, programming languages and platforms, data structures and algorithms, data communications, design patterns, software development for the web, virtual and cloud computing, and more.