Traditional application development involves developers creating monolithic applications on a single codebase. Such a model worked fine when desktops ruled IT. But such a client-server model is obsolete in today’s mobility age and has given way to service-oriented architecture (SOA).

Of late, microservices, a variant of SOA, have soared in popularity. Microservices leverage faster-messaging mechanisms and use nimble NoSQL or micro-SQL databases. SOA adopts an imperative programming style, whereas microservices have a responsive-actor programming style. 

In microservices, applications are a collection of loosely coupled services with lightweight protocols. Such an architectural model delivers significant advantages.

1. Easy and fast application development

Traditional monolithic applications are tightly-coupled and self-contained, with all code residing in a single codebase. Such a model causes significant downsides.

• The UI, logic, and data layers deploy simultaneously for any request. If one of these falls short, the whole application crashes.
• Memory consumption becomes huge, hogging up resources. Caching also becomes less ineffective, slowing down the app. The best example is ecommerce buyers getting stuck on the “pay and check out” page.
• Developers have to rewrite the entire codebase to add or modify a feature. The inability to adapt fast to co-opt the fast-changing requirements makes the application out-of-date in a short time.

The modular nature of microservices overcomes the inefficiencies of monolithic architecture. Application development and maintenance become manageable, and time-to-market improves.

Microservices break the code into independent services, and each service runs separately. The output from one service is the input for another service. Such an architectural model enables:

• Localised changes. Microservices allow changing or debugging specific modules without affecting or causing downtime to other modules. 
• Developing in small increments. It is easier to run smaller modules through continuous delivery and testing. The quality of the code improves. 
• Launching independent services. Developing decoupled or loosely coupled services prevent interdependencies from bogging down the application. 
• Reduced infrastructure costs. Decoupling services spare the need for expensive machines. It is viable to develop robust and functional apps using basic x86 machines. 

But microservices may also become complex. At times, dependencies creep in on adding new features. Such dependencies may introduce faults such as database errors, network latency, or downtime. Success depends on: 

• Designing applications without complex architectural layers or having many interdependencies.
• Robust monitoring capabilities to identify faults.
• The enterprise IT team has the capabilities to deal with such faults. 
• Ability to balance loads.

2. Faster time to market 

In monolithic app development, dedicated teams work on separate functions. For instance, different teams work on UI, database, server-side logic, and technological layers.

In monolithic app development, dedicated teams work on separate functions. For instance, different teams work on UI, database, server-side logic, and technological layers. Such an approach does not suit today’s demands, where competitive advantage depends on speed.

Microservices deliver faster time-to-market through:

• Cross-functional teams. Multiple teams comprising developers, operators, and testers, work on single, independent services. These teams handle the entire life cycle of an application using a continuous delivery model. Such a model requires lesser synchronisation efforts between teams. 
• Code reusability. Reusing code from existing libraries from multiple modules saves time and cost. 
• APIs. Each module has separate databases, and the components communicate through APIs. Multiple instances of communication improve response time. 

But incremental development and continuous delivery keep the enterprise on its toes. The development team needs the capability to provision resources and keep up with the pace of development. The casual, laid-back approach of taking days or months to provision a server no longer works. Success of cross-functional teams depends on 

• Development teams co-opting DevOps practices and culture. 
• Strong management capabilities to bring diverse teams together.

3. Improved Resilience

In the traditional monolithic architecture, the entire codebase has to update even for small changes. Every time the developer has to fix a bug or tweak the code to a new context, the developer has to rebuild the entire codebase and redeploy the software. Also, monolithic applications have a single point of failure. Any failure in the code affects multiple services and functions. 

The decentralised and decoupled nature of microservices architecture makes the enterprise resilient. 

Microservices: 

• Improve flexibility. Developers may replace or upgrade individual components without affecting the rest of the code.
• Enable using the right tool for the right task. Developers may use different languages, frameworks, or ancillary services for each service. For instance, developers may choose Java if a module needs extensive background calculations. Other services may rely on lightweight technologies such as PHP or Ruby. In a monolithic system, the other services will also have to use Java, causing unnecessary load and bloat.
• Localise the impact of the fault. The application functions even when one or more modules fail. For instance, if one module fails due to a tweak gone wrong, developers may confine the downtime to the specific module. As a case in point, Netflix, which uses microservices, will continue to stream movies even if its ”search” option has a problem. If Netflix was a monolithic app, a problem in search could render the entire app nonfunctional.
• Reduce the impact of downtime. IT teams may do maintenance shutdowns in parts without taking down the entire system. 
• Enable device and platform agnosticism. Today’s fragmented technology and fluid tech landscape pose uncertainty. No business can predict the platform or estimate the devices on which their application will run. Developing applications in microservices allows consistent user experiences across platforms or devices.

But success depends on designing for failure. Resiliency testing and fault injection techniques make the code robust.

4. Improved scalability

Monolithic architecture ties everything into a single codebase. As such, scaling a specific function or service becomes tricky. The option is to scale the entire application, which involves higher costs and leads to bloat. 

In a microservices architecture, each service is a separate module that operates independently. Scaling a single function or service becomes easy. Also, developers can deploy services without correcting the entire application. For instance, businesses may deploy business-critical services on multiple servers to improve performance. They need not spend the same effort and investment on other services.

Walmart Canada offers a good case study of enterprises leveraging the power of microservices. The company was an early adopter, having refactored to microservices architecture in 2012. The company earlier struggled to handle six million page views per minute. Adopting microservices enabled the enterprise to cope with huge loads. The conversion rate increased, and downtime reduced overnight. The company also replaced expensive commodity hardware with virtual x86 servers for 20% and 50% savings.

Most successful digital businesses worldwide, cutting across size or location, use microservices. Adopting microservices and developing competencies to overcome the challenges makes the business competitive.