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From Monolith To Microservices – The Journey Towards a Modern Cloud-Native Application

Written by Marius Rimkus
on September 18, 2019

As one of the most important trends to have captured the software world, microservices architecture symbolizes a fundamental shift in how software development is now approached.

While software development was traditionally done using a monolithic development style, major organizations, such as Netflix, Uber, and Amazon, have now shifted to a microservices architecture.

Before we get into further details about microservices and its impact, it is necessary to understand what encompasses the conventional, monolithic architectural style and why modern organizations are looking for alternatives.

What Is A Monolith?

By definition, monolith translates to being composed in one, stand-alone piece. In terms of software development, a monolith application describes a single-tiered application where different components are combined to form a single platform.

While there can be various components in the application, ranging from user authorization to applying business logic and accessing the database to integrating it with other data sources, a typical enterprise application generally features three parts:

  • A client-side user interface – consisting of HTML pages and JavaScript that runs in the user’s browser
  • A database – which includes various tables that are placed in a database management system
  • A server-side application – this handles HTTP requests and is responsible for implementing domain logic, as well as extracting and updating the database among other tasks

The feasibility of handling all your business logic in one single process is the primary reason why the monolithic style of development still remains popular.

Additionally, developers can also use the basic features of their programming language to divide the application into various classes and functions.

The easy-to-develop and easy-to-deploy characteristics of a monolithic architecture have been major contributors to its success. However, the expanding size of enterprises, coupled with the simultaneously growing complexities of applications, has revealed some crucial drawbacks.

As people become increasingly frustrated with the limitations levied by a monolith, many have advocated for a better alternative to developing applications – microservices.

What Is A Microservices Architecture?

As an iteration of the service-orientated architectural (SOA) style, microservices are a software development technique that creates an application based on loosely coupled services.

In stark contrast to the monolithic style, microservices architecture takes on a modular approach as opposed to combining every component in a single platform.

The key idea remains to create applications that are not only easier to build, but far easier to maintain.

This involves the creation of several individual modules that are responsible for solitary tasks - effectively, the application is the aggregate of its related components.

As modern-day enterprises strive to become more agile, the microservices architectural style has experienced a significant surge in popularity.

Features Of A Microservices Architecture

As an entirely different software development approach, microservices architecture has a unique set of features.

Saves Time and Resources

Microservices ensure that the software can be broken down into several services. In turn, developers can make any changes to the specific service without having to compromise the entire application – resulting in saved time and money.

Built For Modern Enterprises

The option to further segment the development process into different components allows businesses to organize the entire application around their preferences.

While conventional application development processes focus on specific factors – such as UI, server-side logic, and database – microservices architecture is based around business capability. This allows teams to be responsible for specific components of the application, leading to cross-functional teams that use less time and require fewer approvals.

Simple Routing

Multiple approaches support the use of a highly complex communication mechanism where products utilize sophisticated systems for message routing, choreography, and execution of business logic.

Microservices, on the other hand, strive for their applications to be as cohesive as possible. It uses intelligent endpoints that are responsible for handling the processing and execution, while a ‘dumb’ lightweight message bus acts as the main router.

Decentralized Governance

Rather than opting to follow a set of defined standards in a centralized atmosphere, microservices developers are more inclined towards the development of advanced tools that can help them, as well as other developers, to solve problems.

As open-source practices continue to become more popular, decentralized governance allows for greater innovation and research.

How Did Monolith Evolve Into Microservices?

A majority of modern enterprise-class systems are styled using a monolith design due to its relatively quicker setup. As such systems continue to grow with time, the structural limitations act as a barrier to further development.

This was one of the key reasons behind the microservices trend; as stakeholders and owners continue to use a monolithic style of software development, they have to wait longer to experience the functionalities they desire.

Coupled with slow and tedious scalability issues, developers require more time to understand and update different facets of the software in a monolithic architecture. The result is a slow, inefficient system that is unable to meet your organizational goals.

This is also why microservices have been hailed as revolutionary; not only do they perform where the monolith architecture fails to, but they provide a greater degree of feasibility and functionality for developers.

With many organizations shifting towards a microservices architecture style, many people are left wondering whether such a switch is worth it.

The evolution from monoliths appears like the right thing to do when you analyze the alternative – a clustered architectural style that is well-suited to modern complex application packages.

The easily scalable nature of microservices, coupled with their cloud functionality, allows businesses the opportunity to test, elicit user feedback, and refine/change their offerings based on insight.

The best part? Businesses can do this swiftly without having to worry about redeploying the entire application. The ability to make quick changes and scale according to requirements makes this a natural fit for the rapidly changing business environment of today.

Differences Between Monolithic And Microservices Architecture

As two opposing software development styles, there is much that separates the monolithic approach from a microservices style.

Maintenance

Monolithic applications operate as a single unit, with each component acting as a part of the system. Updating or maintaining a single component requires the redeployment of an entire application which may prove to be a major productivity setback.

For larger organizations, the redeployment of an entire application can interrupt background tasks and lead to potential problems.

On the other hand, the independent services model of a microservices architecture style allows businesses to update the application software continuously. This is a godsend for developers, particularly interface developers, as they are required to iterate swiftly and redeploy often.

Scaling The Application

A monolithic architecture is one-dimensional, which means that it only allows you to scale in one direction. In the case of increasing transaction volume, a monolith application will simply run more copies of the application.

As applications become more complex, there is a growing need to scale each component according to their requirements. Some components require more processing power while others are RAM intensive – with a monolith style of development, you can’t scale components individually.

In contrast, microservices distinguishes itself on the creation of independent component service modules. This is crucial to scale specific components according to their resource requirements, which allow applications to function smoothly.

The Impact Of The Application’s Size

Modern-day enterprises deploy huge applications; the addition of new features and other variables also contribute to the increase in the package size. But the larger the application, the harder it is to identify errors, update and extract information, and further redeploy the entire application.

As a single-unit software development style, the monolith designed application size has the biggest impact on how it works. The large size means error tracking and elimination is a tedious task, followed by slow delivery as the entire application will start afresh.

The slowed-down rate of identifying errors, making changes and redeployment will eventually translate into lost time.

Microservices software allows separate teams to handle one or more services; this means that whenever an error is identified, the application size has a negligible impact on developers.

Since each microservice works independently, the error can be rectified quickly while other application services handle the requests.

Reliability

Software development and bugs go hand in hand, but they don’t have to impact the entire application. The monolith software style means whenever there is a memory leak in any of the modules in the application, the entire application is affected.

Since all such instances are identical, the bug can extend to impact the availability of the entire application. All it takes is one component to misbehave, and you face a system setback.

Microservices architecture features a vastly improved fault isolation capability feature. Due to the relatively smaller and autonomous nature of the components, only that particular component is affected in the case of a memory leak. This way, users can continue to engage with the rest of the services uninterrupted.

Integration Of Newer Technology

While monolithic applications are more simple to design, they still face difficulty when countering newer technology. Any changes in the language or framework will affect the entire application, which means that substantial efforts are required to update all the details.

Not only is the integration time-intensive, but also requires meticulous and careful effort. In short, when designing a monolith application, you are usually tied down to that particular technology stack.

With microservices, you don’t hold any long-term commitment to obsolete technology stacks. Developers can not only use newer tech to develop services, but they can also opt for a new stack when making changes to an existing service code.

Monolith vs. Microservices? What’s Better For You

While microservices has often been treated as the natural successor to the monolith, the fact of the matter is that both remain widely popular.

In fact, there are cases where a monolith style application can prove to be more beneficial than one developed using microservice architecture.

When To Use Monolith Architecture Design

Here is a list of cases where a monolith design can prove to be better:

You Are Developing An Easy Program

Martin Fowler, one of the most influential voices in the modern software development arena, is recorded to have said:

"...don't even consider microservices unless you have a system that's too complex to manage as a monolith..."

When it comes to complexity, it was one of the key factors that led people to abandon monolith in favor of microservices. It turns out that what works for complex programs will not be utilized optimally when used on a smaller scale.

When you add in the overheads such as design, interoperability of services, etc. the costs incurred will be naturally high. For an application that is meant for straightforward use, this may be a significant deterrent.

You Have A Small Team

A small development and operations team means that only a few people are responsible for the maintenance of the entire application.

In a monolithic application, services are part of the same unit and their interactions are very direct and straightforward. They can also be optimized for specific requests, and, for a small team with prior code familiarity, maintenance can be relatively simple.

With a microservices architecture, the application’s communication is protocol-based which requires even more coding to implement minor changes. This results in more time and resources being used to make the desired changes, putting considerable strain on a small team.

Small Application Size

While breaking larger applications into several modules can do wonders for your efficiency, you need to ask a question: is your application really that big?

Some applications, such as your inventory module or accounts payable module, are already concise enough to be able to work in an optimized manner – not requiring additional component creation through microservices refactoring.

In such cases, transitioning into a microservices model would only add to your complexity as opposed to reducing it.

You Don’t Want To Invest

Many developers use a monolith style when in the initial stages of development or when they are developing a minimum viable product (MVP).

As a non-complex, easy-to-setup architecture style, it allows users to quickly build a product without having to invest in a complex, segmented microservices architecture.

When To Use Microservices Architecture Design

Here are the possible cases where opting for a microservices style of software development can prove valuable:

You Require Scalability And Reliability

For organizations that are dealing with huge application packages that expand across different departments and offices, a microservice design is a perfect option.

For instance, its inherent cloud scalability option and the ability to make swift changes make it a good fit for clients who have a high preference for reliable user experience.

You Are Dealing With A Complex Application

A complex application represents the best possible use-case for a microservice approach that is founded on reducing the complications involved in the process.

Splitting the entire system into separate functionalities not only divides responsibilities, but also allows for easier data management across individual services.

You Require Better Organization

Since each microservice has a very specific job, it allows for better organization. Additionally, by enabling parallel development, microservices architecture can make it harder to make mistakes.

In effect, microservices develop a boundary around every individual service. In turn, this reduces the possibility of common mistakes, such as connecting system parts that should not be put together.

What Should Modern Cloud-Native Applications Look Like

Cloud-native applications are the future; there are no two ways about it.

Consider this: the worldwide cloud services market is valued at $214.3 billion, up by 17.5% in 2019 alone. Organizations are quickly transferring their workloads and application suites online, and as such, there are several features they require.

With newer research and development taking place on the daily, here are some characteristics of what a modern cloud-native application should consist of:

It Should Be ‘Dockerized’

Docker is an open-source software platform used to create, manage, and deploy application containers in an operating system.

Allowing a higher degree of portability, Dockers has become extremely popular due to its efficient application development, low use of system resources, and quicker deployment time compared to virtual machines.

Utilize A ‘Designed For Failure’ Approach

System failures are inevitable – despite many attempts to perfect the hardware and server availability, they still occur. This approach advocates for developers to design applications that support swift and rapid recovery.

Simply put, this leads to quick deployment across redundant cloud components with minimal common points of failure, designing every component to be partition tolerant and distribution of components across availability zones, amongst others.

Autoscaling

As the name implies, this refers to the intuitive scaling of the computational resources in a server farm based on the load.

It allows companies to incur reduced cloud computing charges, allows for efficient energy use, and provides greater uptime and availability.

Infrastructure As Code (IaC)

IaC leads to efficient management and provision of data through machine-readable files, as opposed to physical or interactive configuration tools.

As organizations face scaling problems, this can provide a cost-effective, quick and error-free infrastructure modeling with the help of code.

On a final note

With modern applications becoming larger and more intricate, the software development industry has realized the shortcomings of the conventional monolith design. As major organizations continue to switch to a microservices architecture style, many more will also do so in pursuit of a better data management approach.

While the monolith approach does provide value in certain cases, there is no hiding the fact that microservices architecture allows organizations to become more agile and responsive to consumer demands – two key aspects for success in the modern economy.

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