Monolith Versus Microservices: Weigh the Pros and Cons of Both Configs
A monolithic architecture is an approach to building applications as a single consolidated unit, whereas a microservices architecture is an approach that breaks down applications into smaller, independent services that communicate with one another through APIs.
Deciding which one would be the right fit for you? Read on to learn more.
As the world of software development continues to evolve, so do the architectures and patterns that are used to build and deploy applications. One of the most popular debates in recent years has been whether to use a monolithic or microservice-based software architecture.
A monolithic architecture is an approach to building applications in which all the application’s components are packaged together; though the application may have multiple layers, it is typically deployed as a single unit. Think of it as a single large black box. |
A microservice-based architecture is an approach in which applications are broken down into smaller, independent services that communicate with one another through APIs. Instead of a single black box, think LEGO bricks. |
Both approaches have their advantages and disadvantages, and the choice between the two largely depends on the specific needs and functionality of your application. Is a monolith or microservice-based architecture better for your next application?
In this article, we’ll explore the pros and cons of each approach, how to choose between the two, and tips on migrating. Here’s what we’ll cover:
- What is monolithic architecture?
- What is microservices architecture?
- Monolithic vs. microservices vs. SOA vs. serverless
- Comparing monolithic and microservices architectures
- How to choose between monolith and microservices architectures for your application
- Migrating from monolith to microservices: 5 tips
- Migrate securely to microservices with Akamai Connected Cloud
What is monolithic architecture?
A monolithic architecture is an approach to building applications on which all the application’s components are packaged together. While the application may have multiple layers, such as a database, a services layer, and a front end (user interface), the whole application is typically deployed as a single unit. Think of it as a single large black box.
Within that black box, each layer typically has a separate team that specializes in the technologies used in that layer. For example, a Structured Query Language (SQL) database may be managed by database administrators and developers while a services layer is managed by a dedicated back-end team and the front end is designed by a front-end–specific team (Figure 1).
Fig. 1: The monolith architecture
The pros and cons of a monolith architecture
By keeping all its components and functionality self-contained and deploying them as one piece, an application with a monolithic architecture offers certain benefits. These include:
Simplicity. Monolithic architectures are simple to develop and deploy because they typically involve only one codebase and a single deployment module. This makes it easier to manage and test the application as a whole, which also makes it easier to get started. Additionally, deployments are simpler, as you typically only need to deploy the application to one place.
Specialist knowledge. As an application grows, the development team will typically specialize in one or two parts. For example, you might separate the front-end team from the back-end team. This allows technology specialists to apply deep technical knowledge to the domain.
Of course, monolithic architectures also have disadvantages, including:
Scalability. Scaling monolithic applications can be challenging because, as a single deployment, they need to be scaled vertically. When vertical scaling is your only option, this inflexibility can become expensive.
Flexibility. Monolithic architectures can be inflexible because changes to one component can require changes to the entire application. Additionally, team technology specialization can lead to less flexible teams.
Operations. As applications grow larger, it can become challenging to maintain the monolithic architecture because changes can affect many different parts of the application. A single fault can lead to issues across the monolith, and bottlenecks can be time-consuming and difficult to identify.
Monolithic architecture use cases
Although the prevailing opinion may be that monoliths are “old” and that microservices are the future, this is not always the case. Two examples of monolithic architecture use cases include Segment and Amazon.
Twilio's Segment is an application for which its architects actually switched from a microservices to a monolithic architecture. Their case study argues that the complexity of microservices can create significant challenges for development teams, including increased operational overhead, difficulty in debugging issues, and an increased coordination required between teams.
Amazon Prime Video is another example in which a company considered monoliths vs. microservices and ultimately opted for a monolith application. Its application for monitoring audio and video quality, originally orchestrated as distributed components, became too expensive to operate at scale. Ultimately, their team decided to rearchitect their infrastructure, consolidating all their components into a single monolith application.
These use cases suggest that a simpler, monolithic architecture can allow for faster development cycles and less overhead. Although microservices architectures can be powerful tools in the right circumstances, they should not be seen as a silver bullet for all software development projects.
What is microservices architecture?
A microservice-based architecture is an approach in which applications are broken down into smaller, independent services that communicate with one another through APIs. Instead of a single black box, think LEGO bricks. Each brick can be linked with any number of other bricks; in a similar fashion, microservices interoperate with any number of other microservices.
In contrast to a monolithic team, microservice teams tend to be cross-functional, building at every layer of the stack, and organized according to business unit rather than technology. For example, a navigation app might have separate services that can get directions for different types of transport, such as via a car, bus, subway, or walking.
Each of these individual services might also query other services, if, for example, the car needs access to current traffic conditions, the subway needs to see the current schedule for the given city, and so forth.
With microservices, each service can be developed by a different team — and as long as standards are followed, interoperability can then be realized (Figure 2).
Fig. 2: A possible microservices architecture
The pros and cons of a microservices architecture
When an application is built on a microservice-based architecture, each of the application’s component services is developed and deployed independently. Some of the pros of a microservice-based architecture include:
Scalability. Microservices can be independently scaled, and this yields more efficient and flexible resource utilization.
Flexibility. Microservices are more flexible. Services can be written using different technology stacks, bringing increased agility.
Business fit. Microservices can be designed to be purpose-fit for each business need, and cross-functional teams can work more closely with each business unit.
A microservice-based architecture may look attractive, but it does have some cons, including:
Complexity. Microservices applications can be more complex to develop, deploy, and maintain because they involve multiple codebases and deployment units. Testing these complex applications can be difficult as well, requiring specialized testing environments in which everything is set up properly.
Performance. Microservices can introduce additional latency and network overhead due to the need to communicate with other services. Debugging issues in a microservices architecture can be challenging because it can be difficult to trace issues across multiple services.
- Discoverability. Large microservices fleets can make it difficult to discover what has already been written before, leading to unintentionally “reinventing the wheel.”
Microservices architecture use case
A famous example of a microservice-based architecture use case comes from the Uber Engineering team. In their blog post, they discuss the benefits of using microservices for greater flexibility and scalability, while also outlining the challenges of increased complexity and service-dependency management.
To address these challenges, Uber has developed a set of tools and practices, called Domain-Oriented Microservice Architecture, designed to reduce the complexity of microservices. The post emphasizes the need for standardization in the evolution of microservices.
Monolithic vs microservices vs SOA vs serverless
When discussing monolith applications or microservice-based architectures, additional paradigms like service-oriented architecture (SOA) and serverless are often mentioned in the same breath. For the sake of clarity, let’s briefly unpack these other two concepts before returning to our comparison of monolithic and microservices architectures.
Service-oriented architecture
An SOA is an architectural approach in which an application comprises individual components, with each component providing a specific service across a network communication protocol. Components in the application call on one another remotely to provide a service (i.e., perform its functionality).
In this sense, the SOA started with the monolith application and took a step toward decomposing that application into discrete components. However, SOA services are typically larger and more business-oriented, so they do not decompose as granularly as components would in a microservice-based architecture. An SOA also depends on an Enterprise Service Bus (ESB), which helps to route communication and distribute work among the application’s components.
Serverless computing
Serverless computing is a cloud computing model in which the cloud provider manages the allocation and provisioning of servers. All infrastructure concerns are completely abstracted away, such that developers only need to focus on writing code. Serverless applications are often treated as functions that can be executed at any time. In this sense, a serverless application is event-triggered, running in an ephemeral and stateless compute container.
Many teams that adopt a microservices architecture also choose to deploy their individual microservices as serverless functions. The serverless approach aligns well with microservices in its scalability, cost-effectiveness, and ease of deployment.
Comparing monolithic and microservices architectures
When comparing monolithic and microservices architectures, the following key aspects most notably illustrate the differences.
Scalability. Initially, monolith architectures are simpler and easier to scale. However, with larger enterprise applications, microservices architectures can be more flexible and cost-effective because they can scale in more ways.
Time to market. For a small team with a simple app, a monolith architecture allows for faster development. For multiple teams working on requirements that may change, a microservices architecture allows parallel development and flexibility.
Reliability. Both have pros and cons. Monoliths can have difficulty when changes occur or new features are added, and if something goes wrong the whole app can go down. Microservices typically don’t have such catastrophic failure, but multiple teams making changes at the same time can lead to unintended issues.
Security. Neither is better than the other. Monolithic systems benefit from having technology specialists who work in their field of expertise. A microservices architecture benefits from compartmentalization and a focus on standards due to the need for interoperability.
How to choose between monolith and microservices architectures for your application
The choice between a monolithic approach and a microservices approach largely depends on the use cases of your application and the strengths of your organization. Let’s cover the most important considerations.
Scalability. If your application requires a high level of scalability, a microservice-based architecture may be the better choice because it allows for more flexible and efficient scaling.
Team technical competencies and business culture. If your company has multiple, disparate business units that operate independently, a microservice-based architecture can be a great fit.
Infrastructure and DevOps strengths. A microservice-based architecture requires strong infrastructure and DevOps skills to handle the increased deployment complexity. If your team is lacking in these areas, consider building these skills before moving to microservices.
Migrating from monolith to microservices: 5 tips
Migrating from a monolithic to a microservice-based architecture can be a challenging process. Many others — like GitHub, for example — have gone before you, and we have five tips that can help make the process smoother.
1. Start small
When migrating to a microservice-based architecture, it is important to start small and identify a few services that can be extracted from the monolith. This stepped development process will help you avoid introducing too much complexity into the application at once.
2. Prepare your teams for a culture shift
The move from focusing on specific technologies to working on cross-functional teams organized by business units can be difficult for some team members. Prepare your people in advance.
3. Gain DevOps competencies, if needed
Several tools for hosting and deploying microservices are available — including Docker and Kubernetes. Gain expertise in these containerization and orchestration technologies, and prepare for automated workflows, builds, and deployments of your new microservices.
4. Test thoroughly
When migrating to a microservice-based architecture, end-to-end testing is important for ensuring that all services are working correctly and communicating with one another properly. Add testing and automation for each new service.
5. Plan for service discovery
Plan in advance for how your development team will be able to discover services created by other teams. Over time, you’ll be thankful that you had the foresight to increase reuse and efficiency.
Migrate securely to microservices with Akamai Connected Cloud
Akamai has developed a solution to help businesses securely migrate to a microservices-based architecture. Akamai Connected Cloud is a distributed edge and cloud computing platform that provides security, scalability, and performance optimization for microservices.
Akamai’s platform empowers enterprises to build microservice-based applications and deploy them to the edge. By leveraging Akamai's global network of servers, businesses can securely deploy microservices with low network latency and high availability across multiple regions.
