Enterprise Application Architecture: Best Practices & Strategies
Think of application architecture as analogous to structural architecture. When you build a house, there are many architectural styles to choose from, such as ranch, craftsman, Tudor, colonial, and Cape Cod.
The architecture we select defines our interior and exterior design—and the same principle applies to software. Read on to learn about the many styles of enterprise application architecture.
What is application architecture?
Application architecture is a set of patterns and techniques that organizations use to determine how software should be built.
It defines interactions between the components of an application. It also defines interactions involving core services, such as middleware and databases. Architectures may be specific to an organization, industry, or the type of application.
Architecture is distinct from software design in the same way that structural architecture differs from interior design. Interior design options follow the architectural design of the building that houses them.
Similarly, software designers create designs based on a foundation of architectural principles. The architecture is the set of guardrails that guides design.
Why do we need an architecture for applications?
There are several reasons why the architecture of applications is important:
- It reduces complexity by limiting the set of services used and accessed consistently.
- It reduces costs by limiting redundancy and technology sprawl.
- It provides a consistent roadmap for others to follow when modifying an existing application.
- It improves efficiency by specifying which services are best suited for different types of applications.
For example, sound architecture recommendations might include a specific relational database management system for transactional applications.
Similarly, developers might prefer a specific NoSQL database for analytical use based on the application architecture.
Most architectures incorporate three basic layers:
- The database layer includes modules related to low-level dependencies such as servers, databases, networks, storage, and middleware.
- The business layer includes modules that set logic rules specific to the business. Examples include currency calculations, workflows, application interfaces, and data models.
- The presentation layer defines the way users interact with the application. Examples include menu structure, navigation schemes, and placement of interactive components like buttons.
Examples of other layers that may also be used include:
- Functional layer: Specifies how the system behaves based on business rules
- Application core layer: Sits just above the database
Sound architectural principles specify that each layer may communicate with layers below but not above. This rule prevents creating dependencies that can increase complexity and result in so-called “spaghetti architecture.”
Application architecture best practices
An effective application architecture:
- Withstands the test of time
- Reinforces an organization’s software development methodology
- Maximizes flexibility, and minimizes complexity and technical debt
Application architecture is also consensus-driven, with everyone involved in specifying and building software agreeing to the definitions and services.
Enterprise architecture best practices maximize reusability for both scale and speed. They should also minimize dependencies between layers by specifying conditions for communication between them.
For example, the database layer should never depend on functions at the presentation layer to avoid creating unbreakable dependencies. It’s also important to isolate end-user services at the presentation layer to accommodate multiple users simultaneously. This rule also prevents user sessions from becoming dependent on a neighbor’s business or database services.
Even within layers, minimize co-dependencies. For example, contracts and customers are closely related, but each element should be able to exist without the other. If dependencies are necessary, then combine the elements in a single module.
Select modules to include in layers with care. Don’t define business rules in the database layer, and don’t define database rules in the business layer. Business layer modules should be limited to those functions that are specific to the company’s business rather than general-purpose tasks like authentication or validation checks.
As a rule, avoid direct interactions between the presentation layer and the database layer. A safe approach is to expose public data as read-only and make updates subject to security controls.
7 types of application architecture
Architecture types have increased as the range of options available to developers has expanded. Here are the most common enterprise architecture examples.
1. Monolithic architecture
Monolithic architectures are usually associated with legacy systems developed before modern services-oriented constructs were available. In this architecture, all functionality is self-contained. With every change, the team must test and recompile the software.
Monolithic software is complex, doesn’t scale well, and is challenging to update. However, it is useful for small projects with simple functionality and low-traffic tools. Examples of acceptable use cases include web calculators and blogs.
2. Service-oriented architecture
Service-oriented architectures emerged in the 1990s and evolved into modern microservices. This approach breaks down applications into discrete and reusable services.
These services communicate with each other through a common enterprise service bus. They typically use message queuing or publish-and-subscribe techniques to exchange messages asynchronously.
3. Microservices architecture
Microservices architectures are widely used in cloud-native, agile development environments like DevOps. This approach breaks down applications into the smallest possible components. These components are loosely coupled, functionally independent, and reusable. Developers assemble applications from microservices, enabling rapid software development.
The resulting applications scale well. They are also resilient — the failure of individual services does not bring down the entire application. They also allow the introduction of improvements without disruption. Multiple developers can work on the same application concurrently.
4. Event-driven architecture
Event-driven architectures are widely used in real-time processing and self-service scenarios. Instead of processing batches of data on a predefined schedule, event-driven architectures respond to an event, such as the press of a button or the swipe of a credit card.
Event-driven applications are often built on top of microservices architectures because an event kicks off a set of specific tasks associated with that action.
5. Web application architecture
Web application architecture is specific to programs that run in a browser as well as many mobile applications. It defines the usable components and their logical interactions in the context of the internet’s distributed nature.
Web application architectures have become considerably more nuanced as browser capabilities have improved. For example, progressive web applications work on any browser and provide rich functionality even without an internet connection.
Web app architecture can dictate where logic and user interface elements are stored, as well as the order in which webpage elements load.
6. Mobile application architectures
Mobile application architectures are similar to web apps but with the greater processing, memory, and storage capacity of mobile devices. They also specify constructs for portability across platforms.
7. Serverless architecture
Serverless architecture is the most recent evolution of the microservices model and is still relatively rare. With this approach, cloud-based third-party services inside software containers construct applications.
Serverless functions scale well and can be spun up and shut down very quickly. Serverless is also one of the least expensive ways to deploy software because cloud instances are unnecessary. Popular uses include event processing, image recognition, automated software testing, and machine translation.
How to choose the right architecture
No one architecture is right for every use case, but most are flexible enough to fit multiple scenarios. You can narrow down your choices by starting with the needed functionality and working down to the underlying platform.
In some cases, elements of multiple architectures may need to be combined. Here are some factors to consider as you determine the right architecture.
|What functionality is necessary?||The more complexity involved, the more you should lean toward microservices or serverless architectures. Relatively simple on-premises applications may only require a monolithic or service-oriented approach.|
|How important are performance and scalability?||Microservices-based applications deliver the best on both fronts. Elements of web application architecture may also distribute some processing to user endpoints.|
|Where will the software live?||If the application exists in the cloud, apply cloud-native constructs such as containers and microservices. If it runs on a specific cloud, use the architectural frameworks provided by the platform operator (e.g., Amazon Web Services).
Software that runs behind the company firewall can use service-oriented or microservices definitions specific to its environment.
|How rapidly will the application evolve?||If you plan to make significant or rapid enhancements, use a services approach. A monolithic architecture may be fine for an application that is purpose-built and changes infrequently.|
|What is the skill level of your development team?||This is a key question since microservices, containers, DevOps, and serverless development differ greatly from traditional techniques.
You may want to go with a more mature monolithic or service-oriented architecture until your team is up to speed and then transition to new constructs gradually.
Today, organizations have more choices than ever in building software. While choice can cause paralysis, there’s no reason why development teams should hesitate to begin transitioning to DevOps techniques and modern cloud-native technologies.
A robust application architecture should accommodate new technologies as they become available and be suitable for traditional “waterfall” development and agile practices. By adhering to sound practices for defining layers and the rules around them, development teams can create an architecture that is adaptable, future-proof, and fundamentally solid.