Monolithic architecture vs. microservices: Which works best for you?

The monolithic approach is the traditional software model. Microservices reflects later software development, but that hasn’t rendered monolithic architecture obsolete.

Let’s say you’ve started working for a tech startup and you’ve been tasked with implementing an IT plan for the new company. You face a litany of decisions, but none as basic or as far-reaching as settling on a monolithic architecture or microservices architecture. The choice of software architecture shouldn’t be made in a vacuum or without a clear understanding of your organization’s initial and eventual data processing needs because whichever architectural approach is chosen will have profound effects on the organization’s ability to meaningfully execute on its business goals.

So, the stakes here are considerable. And because you’re the newly named Director of IT, it’s also a weighty decision for you personally—one that might lead you to a golden path of untold career advancement, if you choose wisely.

Which do you select? First, let’s meet your options.

As stated, monolithic architecture is the traditional software development model. In it, one codebase carries out multiple functions (that is, business functions). The computer kernel controls all functions. In monolithic applications, all the code required for that entire application is maintained within a central location.

Monolithic applications usually contain the following components:

• Client-side user interface (UI): “Client-side” relates to what’s displayed on the computing device of the user. The UI manages what’s 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: Monolithic architectures use a relational database management system (RDMS), a type of database that organizes data into rows and columns. These rows and columns form a table where the data points are related to each other.

• Server-side application: A server-side application deals with server resources like memory, CPU and storage.

Using monolithic architecture yields numerous benefits:

• Uncomplicated application development: Applications constructed with a single codebase are simpler to build with faster development.

• Basic deployment: Monolithic architecture works with one executable file or directory, which makes deployment less difficult. A monolithic architecture is also easier to maintain by virtue of using fewer components.

• Simple debugging: Testing and debugging operations are less involved with monolithic architectures. End-to-end testing operations are enacted from a central logging system.

• Boosted security: Because a monolithic architecture is a closed system, its data processing activities are fully contained and protected against cyberthreats.

Monolithic architecture use also presents possible problems:

• Resistant to new technologies: Because monolithic applications are typically tightly coupled, it can be difficult to integrate new technologies into them.

• Reduced scalability: Even if the amount of scaling needed is relatively minor (like adjusting a single function), you might have to effectively dismantle and rebuild the system to reflect the new change. That can prove time-consuming and labor-intensive.

The other software development model—microservices—is a cloud-native architectural style. With microservices, an application is based on multiple, loosely coupled, individual components or services. Microservice applications have their own technology stack, which is a collection of technologies that work together to get a particular job accomplished.

The primary advantage of microservices is how the system can be easily updated to address new business capabilities within the application without impacting the entire system. This can translate into hefty savings of both time and labor.

The advantages of microservices are numerous. They accommodate both constant business growth and new technological changes:

• Increased scalability: Microservices excel at scalability as compared to monolithic architectures. Individual services within a microservices architecture are broken down into modules, and a single instruction to scale upward can be transmitted to multiple services simultaneously. Also, microservices are well suited to handling large and complex applications.

• Automation-ready: Microservices in use enable organizations to automate the continuous integration/constant delivery (CI/CD) process. This permits the development of code updates that occur according to a continuing schedule.

• Independent operation: Microservices architecture splits each service into an operational cell. With this type of independent operation, there’s no danger of workflow for one microservices application intruding upon the workflows of other microservices applications.

Microservices offer definite benefits, but their complexity does create certain problems:

• Testing hurdles: With microservices, debugging operations don’t start until the various parts of an application have been tested. This includes checking dependencies, caching activities and data access.

• Potential security exposure: The data exchange that takes place between various processes within a microservices system uses an application programming interface (API) gateway. An API gateway can create security vulnerabilities in authentication and other critical activities.

• Uptick in latency: Microservices scale up applications impressively, but this can create problems with additional lag and latency. Any time the system scales upward, it raises the complexity and amount of data being transferred, and this can slow down processing.

Before our head-to-head comparison of monolithic architecture and microservices architecture, we should flesh out the story with some historical details to provide a broader context.

In some ways, it’s difficult to trace the origin of monolithic architecture to a single date; the more complicated the technology, the more difficult it can be to pinpoint the exact delivery of that technology. And so it is with monolithic architectures, which began to be developed around the middle of the 20th century.

International Business Machines (IBM®) was a major player in that critical early development. According to DZone contributor Pier-Jean Malandrino, “…companies like IBM were instrumental in defining early software architecture through their development of mainframe computers in the 1960s and 1970s.”¹

Monolithic architectures were not perfect—they were often written in ultrabasic languages and were intended to be read by a single machine. Because only one machine contained the entire system, all the computer components were tightly coupled. Scaling was either nonexistent or barely possible, usually requiring the complete rebuilding of a system.

Alternatively, if monolithic architecture appears primitive in hindsight, it’s partly because it was there first, before any other system of software architecture. And it’s proven consistently useful, even resilient, over time. The fact that monolithic architectures are still being used seven decades after their introduction speaks volumes in an industry in which the only thing that usually remains is ceaseless change.

Monolithic architecture has endured but it’s no longer the only game in town, and it hasn’t been for some time. As the 1980s progressed, software engineering experienced a drive toward modularity and the use of object-oriented programming languages. By the 1990s, the stage had been set for distributed systems that might take advantage of recent advances in network computing.

This eventually led to the development of microservices, which came into broad use after the start of cloud computing and containerization technologies in the 2000s. Microservices architecture was created to improve upon the monolithic model by gearing it for rapid scaling and decentralized systems.

Now, in the 2020s, software development spins from either monolithic architecture or microservices architecture. Based on what we’ve come to expect from technological change, our initial thought might be to assume that the technology that’s arrived more recently is superior, and in some circumstances, that’s definitely the case.

However, making that kind of blanket statement is dangerous, largely because it’s simply not true. There are still numerous computing situations that benefit from the simplicity of the monolithic architecture model.

Both software architectures have their advantages and drawbacks, and companies need to carefully evaluate both types and consider their projected application development needs before adopting one system or the other.

How do monolithic architecture and microservices architecture compare when viewed through the prism of key operational stages?

• Creation: The key differences between the two architectural formats start early, with concepting the wanted system. Monolithic systems are simpler to build because they use a more basic design. Microservices are considerably more complex and require more planning to execute.

• Structure: A monolithic architecture is designed and constructed as a single unit. Microservices architecture champions the idea of modularity by using a collection of smaller, deployable applications that enable the operation of independent services.

• Complexity: The more complicated a system becomes, the better it’s suited for a microservices architecture. Modular microservices is welcoming of new features and new technologies that tend to accompany added complexity.

• Growth: Monolithic architecture and microservices architecture can both be effective during their initial use. But growth changes everything, particularly when organizations realize that they are soon to expand beyond their initial system. At such a point, companies need a larger stage of operations, and microservices provide that by featuring more ways to scale operations than monolithic architecture can.

• Time to market: This key metric plays a pivotal role in commerce by gauging the amount of time that it takes to manufacture goods and enter them into distribution channels. Time to market is an area where monolithic architecture excels beyond microservices. By using only a single codebase, developers can avoid the extra time and labor of incorporating software from various sources.

• Scalability: Microservices architecture is built on individual services that can be compartmentalized in modular forms and benefit from loose coupling and intercommunication achieved by using APIs. On the other hand, monolithic architecture displays less overall adaptability due to having a thickly composed core structure and tightly coupled software.

• Debugging: Debugging is the process of using software to sense and locate coding problems, and then remedying those issues. Monolithic architecture handles debugging better than microservices because it’s simpler and more straightforward. Debugging a microservices architecture is considerably slower, more involved and labor-intensive.

There is a near unlimited supply of use cases that can be achieved by using either a monolithic architecture or a microservices architecture. Here are some of the most prevalent.

• Startups: Companies just starting out need two things: flexibility and start-up funding (and plenty of both). A monolithic architecture is the best way to start fledgling businesses. Further, it can be constructed by lean development teams in a cost-effective manner that doesn’t impose too steep a learning curve on those small teams.

• Basic projects: Having a single codebase pays dividends in convenience, especially with projects that are rudimentary in scope. When the software can go through the development process without needing to incorporate data from multiple sources, it’s a win for the organization.

• Entertainment platforms: Running an international entertainment platform requires the ability to ride the changing tide of workloads, whether that demand turns into light workloads or heavy workloads. In the case of Netflix, the streaming video giant transitioned from a monolithic architecture to a cloud-based microservices architecture. The new Netflix backend contains plenty of load balancer support, which assists its efforts to optimize workloads.

• Ecommerce: Ecommerce depends on microservices architecture to make the magic of the electronic marketplace come alive with a seamless user experience. With ambitious retailers like Amazon (AWS) prompting sales with greater convenience and faster delivery, it’s easy to see why the 2023 ecommerce sales market topped 5.8 trillion USD.²

• Toughest jobs: The ongoing use of microservices typically requires the implementation and administration skills of trained DevOps teams who can go about creating the specific services needed for that architectural framework. Those skills are especially useful when encountering complex applications.

Any full-scale implementation of monolithic architecture or microservices architecture will be inevitably misguided if its design is completed in an effective vacuum, without first considering the most important part of the equation—your tech startup’s particular needs.

As Director of IT, this is the most critical activity when planning your software infrastructure decisions. Knowing when to use an architectural style is essential, as is understanding the most suitable system based on your needed uses.

The self-analysis exercise is highly valuable because it’s your job to not only select the optimal architectural system for your organization, but also to accurately estimate the architectural system your company will need in months and years to come. In some ways, you’re being tasked with the job of predicting the future.

So, while a monolithic architecture might seem perfectly ideal for your startup, it’s up to you to project future growth. And if rampant expansion is expected, it might prove wiser to go ahead and invest in a microservices architecture. There are numerous variables to consider:

• Business logic in use: Just as computer logic dictates what is and isn’t possible with a computer, business logic is based on business rules that govern how a business can and can’t be operated. Technically, it translates into the algorithms that define how information is passed between a database and a user interface.

• Front-end development: As early as planning the front-end of your software architecture, you need to define which architectural approach you are following, because each has a unique structure. In a monolithic architecture, the front-end application is manifested as one large codebase that houses all application code. In a microservices front-end application, multiple independently operating microservices can be put into operation.

• Fault tolerance: Another consideration that must be made involves how much fault tolerance is expected to be needed. Fault tolerance is a very tricky issue, because it can bring down an entire application if just one component in that system fails. A monolithic architecture lacks any isolation between components, and that can aggravate the lack of fault tolerance and lead to extended periods of downtime.

• Expected rate of change: The choice between monolithic architecture and microservices architecture is not merely a matter of software architecture. It’s really a selection between two business mindsets, one that simply wants to get into operation and another that insists on achieving substantive business growth. Growth can be tricky, but it’s well supported by microservices architecture attributes like faster development cycles and boosted scalability.