Monolithic vs microservices—which is better?

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Contents

Applications and service-based software are usually built using either monolithic or microservice-based architecture. There is an ongoing conversation as to which one is best for businesses to adopt for their projects, so we’re going to examine the good and bad of each, and so be confident of making an informed decision as to which is best for which kind of project.

When an application is created using monolithic architecture, the functions, data objects, and events are mediated by a single, indivisible unit. Making changes to, and especially extending and scaling, a monolith can be complicated and not without problems. Because everything is contained in one system, this can lead to unwanted changes if even one small change is made to a single component.

Where microservice-based architecture is employed, though, the components are not all held in one single block of code, but are partitioned into independent service units—literally, a “microservice.” Each such component is isolated, meaning that it has its own code and data, and is ideally not reliant on or linked to other components.

Instead of the large single unit found in the monolithic architecture, microservices offer a modular approach where individual units can be manipulated and changed without worrying about the consequences for other components.

 

Monolithic vs microservices—market adoption

Monolithic architecture has been the go-to, standard approach for businesses creating a software application. This isn’t necessarily because monolithic architecture is the best, or a one-size-fits all approach that can lend itself to guaranteeing good results on any project. It’s just been around longer.

Microservices aren’t completely new though, having caught the attention of the mainstream in software development in 2011.

Since then, interest in and use of microservices has been growing, with companies like Amazon and Netflix being early adopters of the approach, adding to the legitimacy of microservice architecture.

Evidence shows that companies are now moving towards adopting and adapting to using microservice architecture. However, like monolithic architecture, microservices do not offer a solution that is right for every project, all of the time. Indeed, there are some issues connected with microservice infrastructure that can make adopting this system a bad choice.

We’ll be looking, then, at more precise descriptions of both types of architecture, the advantages and disadvantages of both, and in what business contexts each type of architecture might be the most appropriate for a business to adopt.

 

Monolithic vs microservices differences

Formerly, monolithic architecture was the default method for developing both simple and complex applications. Monolithic architecture is so-called because any application built using it is then a single, indivisible unit.

 

Created to handle various different tasks and services, they usually contain a frontend UI, a backend server application, and a database. All of these functions come as a single package and are kept in one single place.

This brings some issues and disadvantages that have seen its usage decreasing, because applications built on monolithic architecture lead to significant difficulties linked to the massive code base.

If the app is complex, this codebase is going to be very large. As the codebase is responsible for all functionality of the app, there is therefore no modularity. This means that if developers want to change or update one part of the system connected to a specific function, the size of the application makes implementing changes challenging, requiring the redeployment of the entire app.

It should be clear what microservice architecture looks like after considering these core features of the monolithic. Rather than an infrastructure based on something single and indivisible, the development process here works toward creating discrete, independent modules that come together to form the whole.

Each function is carried out by an individual component module. Where monolithic architecture has the whole responsible for each function, microservice architecture employs independent units.

This creates an organisational structure that is modular and demarcated by function and service, with each part communicating to the others to deliver overall functionality. This means that each module, or microservice, can be updated, deployed, changed, or scaled by the developer on a case-by-case basis, without the overall structure having to be redeployed each time.

 

Monolithic vs microservices-pros and cons

 

Industry Knowledge

Monolithic architecture has always been the default process for application development. This means that all developers and engineers are able to create apps based on this model easily and without the need for further specialisation. However, as noted, since 2011, microservices have been widely recognised in the software development space with more and more developers now picking up the specialisations required.

 

Deployment

A monolithic application is a single indivisible unit. So, while there is one massive file or directory to be deployed, there is nothing else. The need for multiple deployments is therefore avoided.

However, due to “tangling,” changes are not usually isolated. One change can affect the entire system, so great care must be taken, which makes the overall deployment and development time for a project significantly longer.

Microservices are independent and can be changed and deployed as and when needed, without the need to redeploy the whole. This can save time, but as it involves multiple components, the time cost can still be significant. How serious this drawback can be depends on both the size of the project and the available team.

 

Cross-cutting concerns

Applications have components and aspects that are related to the other components and aspects, meaning that code can be duplicated or that different parts become dependent on other parts. This concerns processes such as logging, caching, and error detection, among others.

This interdependence, or tangling, means that modularity is lost, or at least shows that components are not genuinely individual. The consequences for modularity are not a serious issue in monolithic architecture, as the code and database are already written with singularity and interconnectedness in mind. This includes the anticipation of solutions for issues when they arise, making it easier to debug when necessary.

Microservice architecture has modularity as a core feature, however, so any cross-cutting concerns arising here are more serious for the architecture. Health checks, security testing, external configuration, and metrics need to be developed and checked for potentially hundreds of the different services. This can potentially take days for each service, meaning alternative methods such as service templates will have to be employed.

 

Scalability

The lack of modularity in monolithic architecture means that the entire unit would have to be scaled, which entails everything having to be rewritten, as the size of the code becomes more complex. This can be an advantage, however, if the code and database are located on a single server, as it is easier to work on one unit than multiple microservices.

With microservices, upscaling involves working with multiple components instead of one large unit. Developers need to decide, then, if it is necessary to work on upscaling all of these components simultaneously, or if they should identify specific components to upscale individually. This also gives rise to another issue connected with the above-mentioned cross-cutting concerns, as developers would then have to further check that the upscaled services can still work with the rest of the components.

Of course, if developers can deal with the issues of working with multiple components, then microservices architecture can here offer great versatility and flexibility as to which services are upscaled and when, depending on the business and project needs of the app.

 

Performance and speed

Each microservice is an independent modular component requiring developers to deploy API gateways to connect them to each other and so allow communication. This number of requests can create bottlenecks, so leading to delays and reduced performance.

Conversely, if any individual component is overworked and is causing lag, then it can simply be cloned and deployed as another discrete unit that can work in tandem with the original. This greatly reduces demand on the system, and is another good example of the versatility and flexibility inherent in microservice architecture.

Monolithic architecture has no such issues with bottlenecks or lag, as the architecture does not require communication to take place between disparate units, but is local and based on its server-side, allowing for a faster response time.

 

When should you choose monolithic or microservice architecture?

The differences and relative merits and demerits between the two types of architecture are now clear. So, which one is the most appropriate for you and your business goals?

As usual, the best choice depends on business context and resources. The complexity, time, and cost concerns of a microservice-based app are not going to be advantageous for a new start-up with a small team working on an initial investment. Here, the monolithic architecture that all developers are familiar with and that has a faster deployment time will be more appropriate.

The familiarity of developers with the architecture is a key concern. As noted, as monolithic is the industry standard, any team will have the know-how to develop around this.

Microservices, however, require specific expertise, and so developers are more difficult to find and more expensive. Using developers who learn as they go to gain the requisite expertise is a gamble and entails a greater chance for errors.

The type of application should also influence the decision as to the best architecture. Business aims involving a simple application that will not require large scaling over time and that doesn’t have multiple functions will fit a monolithic architecture much better.

Likewise, the above-mentioned ease of deployment and cost-effectiveness of the monolithic model increases the chances of an MVP being created and launched very quickly, which is more challenging to achieve with a microservice infrastructure given the added complexity of individual components adding to minimum deployment time.

Conversely then, business contexts that involve very complex apps are going to prefer adopting a microservices architecture due to the superior scope for scaling such apps without the need for complete rewriting. Likewise, adding new functions and capabilities to the app as and when the need arises is much quicker and easy with microservice architecture.

It is for this reason that large or even huge SaaS and ecommerce sites adopt microservice architecture. The resilience of the system and the ability to handle large amounts of traffic mean that pages and apps that are multi-functional and that are very complex will fare much better on a microservices system. This is often tied in to the fact that such companies have the resources to employ large teams who can respond to the needs of managing such large systems and dealing with the work required for each component as it arises.

Large, established businesses and corporations might consider microservices architecture as they can meet the expense connected with employing a specialised expert team of multiple members to work with potentially thousands of individual components and API management. This means that cost and time constraints can more easily be factored in, resulting in a project being realised that allows for complex apps to be built and updated as and when required.

 

Final takeaways

In conclusion, a business working toward testing a new idea and requiring the production of an MVP to test proof of concept should adopt monolithic architecture. A small team creating a simple application with a knowledge base available to all developers will be able to create a monolithic application with no issues. In this case, there is no need for the adoption of a microservices architecture.

Complex apps and those that require multiple changes, updates and additions, however, are much more suited to microservice architecture. This is because the modularity allows such changes to be made on a case-by-case basis, quickly and effectively. This, though, requires an experienced expert team, so is better suited to large companies with the financial resources sufficient to cover this.

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