One way to think about monolithic architecture is to visualize the term’s other meaning. When considering the design of actual buildings, we refer to monolithic architecture to describe structures that are cut into massive rock formations. An associated meaning of the core word “monolith” relates to the fact that its substance is all of one piece, making its composition completely uniform. Several co-attached buildings might be created from one formation—all of them sharing the same base of rock.

This analogy translates well to our discussion about software engineering. Within this context, a monolithic architecture fulfills business functions (i.e., creates different buildings) that vary but share a single codebase (or rock base).

For decades, monolithic architecture completely ruled software development as its traditional software model. Now, however, any relevant discussion of monolithic architecture must contemplate its great alternative—microservices—which are being used in increasing numbers.

In monolithic software, all the code required for an application is kept in one central location. This provides an added simplifying benefit to developers because the system is geared to only accept communications in one format. The system is not taxed with the burden of translating communications from different services. This makes development processes like DevOps easier to execute.

Monolithic applications usually contain the following components:

• Client-side user interface (UI): In this context, “client-side” is associated with what is displayed on the computing device of the user. The UI manages what is seen by the user, including images, text and anything else that can be transmitted over the UI screen, like information related to browser actions.

• Database: A monolithic architecture uses a relational database management system (RDMS) that consists of numerous tables.

• Server-side application: A server-side application deals in some way with the server’s resources, with access to server resources like memory, CPU and storage.

Examining monolithic architecture in greater detail, we can see that it affords several significant advantages:

• Easier application development: Applications constructed with one codebase are easier to build.

• Simple deployment: Monolithic architecture works with a single executable file or directory, which eases deployment. Further, a monolithic architecture is easier to maintain because it uses less components.

• Hassle-free debugging: Testing and debugging operations are considerably less intensive with monolithic architectures. These end-to-end testing operations can be enacted from a central logging system.

• Increased security: Because a monolithic architecture is a closed system, its data processing activities are fully contained and therefore more protected from cyberthreats.

With monolithic architecture use, we see that what appears to be a strength (its rigidity) can also be viewed as a weakness:

• Resistance to new technologies: Because monolithic applications are typically tightly coupled, it can be difficult to integrate new technologies into them. In fact, what usually happens is that the monolithic application must be retooled completely to accept the new addition.

• Reduced scalability: Scalability is the greatest challenge monolithic architectures face. Even if the amount of scaling needed is relatively minor (like adjusting a single function), you may have to effectively dismantle the system and rebuild it so it reflects the new change. That can prove time-consuming and labor-intensive.

Microservices architecture is a cloud-native architectural style wherein one application is composed of numerous, loosely coupled smaller components or services. Microservice applications have their own technology stack (a collection of technologies that join forces to get a particular job performed).

One of the main business advantages provided by microservices is the way the system can be easily updated to reflect new parts of the application without impacting the entire application. This can translate into hefty savings of both time and labor.

A close alternative to microservices architecture is event-driven architecture (EDA), which is sometimes used in tandem with microservices. In EDA, state changes are represented as events and are scheduled within the system. EDA offers loose coupling and real-time processing, making it an attractive option.

Microservices are primed for constant growth and accept technological change. Here are the main benefits they provide:

• Scalability on tap: Microservices offer greatly increased scalability when compared to monolithic architectures. Because individual services are broken down into modules, an instruction to scale upward can be delivered to multiple services simultaneously. Also, microservices are better suited to handling large applications.

• Geared for automation: Microservices allow organizations to automate the continuous integration/continuous delivery (CI/CD) process. This enables development of code updates that occur on a continuing schedule.
  

• Independent operation: Microservices architecture splits each service into its own operational cell. By enabling independent operation, there’s no danger of workflows for one service intruding upon the workflow of another.

Although microservices offer numerous advantages, their overall complexity underpins some of the problems their use creates:

• Complicated testing: With microservices, debugging operations can’t even begin until the various parts of an application have been fully tested. That includes checking the dependencies, caching activities and data access. Everything must work, and it all must work together.

• Security issues: The communication that occurs between various processes within a microservices system uses an API gateway. This can create a security exposure when it comes to authentication and other critical processes.

• Increased latency: Microservices are especially talented at scaling up applications, but there’s a price to be paid in extra lag and latency. Every nuance of up-scaling raises the complexity and amount of data, which can slow down processing efforts.

The advent of microservices has turned software development into a two-horse race between upstart microservices architecture and the traditional monolithic approach to software architecture.

A quick glance at that race might suggest that microservices are the superior architecture since they were the later development. However, that assumption would prove shortsighted. There are still numerous computing situations that benefit from the simplicity of the monolithic architecture model.

Further, both software architectures have their advantages and drawbacks, and organizations would do well to take a hard look at both types and consider their projected application development needs before adopting one system or the other.

In terms of direct areas of comparison, monolithic architecture and microservices differ in numerous key respects:

• Structure: A monolithic application is constructed as a single unit, while microservices architecture reflects a different approach, via a collection of deployable services that are smaller and operate independently.

• Creation: A monolithic system is easier to build than one based in microservices architecture, thanks to it having a more basic overall design. Microservices architecture requires the use of a design that’s considerably more involved to plan and construct.

• Complexity: As the complexity of a system grows, the more it becomes a better fit for the microservices architecture model, which offers a dynamic programming foundation that accommodates the future adding of other functionalities and new features.

• Scalability: Microservices architecture is based on well-defined individual services that are easily compartmentalized into modular forms with loose coupling and which can communicate with each other through APIs. Monolithic architecture possesses less adaptability by virtue of its thickly composed core structure and tightly coupled software.

• Debugging: The process of debugging (or using software to detect coding problems) is an important part of responsible operations. Although one might think that this was an area where microservices has a definite advantage, quite the opposite is true. Debugging works better in a more straightforward context, which is exactly what monolithic architectures offer.

• Time to market: Time to market is a key metric in the world of commerce, measuring how quickly goods can be manufactured and put into distribution channels. Monolithic applications only use one codebase, which frees developers from having to incorporate software from multiple services, resulting in faster time to market.

• Business capability: Either architecture can prove effective enough when an organization first begins to use it. The challenge comes with the appearance of business growth and when those companies develop enterprise needs that require a larger stage of operations. That’s when microservices really establish their worth, by offering more ways to scale operations than monolithic architectures can.

Knowing when to use an architectural style is essential, as is understanding the most suitable system based on your needed uses. These are the best usages of a monolithic system:

• Startups: Startup outfits need to make quick business moves, but also need to conserve precious start-up funds. For these reasons, a monolithic architecture model makes perfect sense for new companies. A monolithic system can be easy to learn and quick and cheap to use, while adapting to using microservices architecture can be a costly and time-consuming affair.

• Basic projects: Monolithic architecture is perfectly suited to handling application or prototype development—provided the app or prototype in question is simple in nature. This is due to the easiness of using a single codebase. The software can be fully developed without the need to integrate data from various sources, making it easier to use.

Microservices lend themselves to many projects, including the most complex applications:

• Ecommerce: Ecommerce has come a remarkably long way in a relatively brief period, broadly rewriting the sales strategies of countless retailers that have unshackled themselves from the massive building costs associated with brick-and-mortar sales operations. The 2023 e-Commerce sales market climbed to a dizzying 5.8 trillion USD, driven by omnipresent and market-vigilant retailers like Amazon (AWS).¹

• Entertainment platforms: When operating an international entertainment platform, you must be able to withstand both light and heavy workloads. In 2009, streaming video giant Netflix transitioned its system from a monolithic architecture to a cloud-based microservices architecture. The Netflix backend now includes applications from Apache, Cassandra, Chukka, Gluster, Hadoop, Hive, JavaTM, MySQL—with ample support for load balancing.

• Expert teams: As stated earlier, microservices are simply not as easy to use as monolithic architectures. They require practitioners who can bring established skill sets to their work. Further, microservice architectures usually need the support of multiple technicians, due to the overall complexity of the operation. For these reasons, fully staffed teams of experts are an ideal match for working on microservice architectures and microservice application development.