The Real Difference Between Microservices vs SOA vs API Explained

In software development, there has been a major drift in the way organizations invest, deploying an architecture-oriented approach. It all started with SOA and then transfigured into something that we call as Microservices. Added to them was another concept, designated as API.

For the past few years, SOA and microservices have remained a topic for discussion. With time, organizations feel the need to transform their workflow and adopt microservice for their software systems.

To start with, we define each of them separately and figure out where the difference lies.

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APIs or Application Programming Interfaces

APIs or application programming interface is a lightweight protocol used by developers for initiating communication between client and server. APIs are all about adding transparency while allowing multiple products or services to interact with each other.

It becomes easy to upgrade an existing infrastructure by adding distinct applications with the help of APIs. APIs extend support when organizations need to migrate to the cloud or shift their existing applications to the cloud. Given the ease rendered, APIs help enterprises collaborate with the teams of IT for integration with cloud-native applications. That’s where the concept of microservices comes into the picture.

The majority of the cloud-driven operations are based on microservices and they use APIs to connect to the same.

As per WSO2, APIs now account for 25% of internet traffic.

Developers find APIs, one of the most convenient ways, when they seek to connect the organizational ecosystem with the cloud-driven app.

Salient Features of APIs

• Outline protocols that determine the manner in which two parties connect.
• Allow developers to enhance the productivity of developed applications by integrating third-party services.
• Allow microservices to communicate with others.
• In the connected world of today, information is being shared via APIs to external and internal teams, security is a top concern. APIs provide adherence to security standards and safety needs.

SOA or Service Oriented Architecture

SOA is an enterprise-oriented form of architecture. It is regarded as one form of software development where different modules of the applications render services to another taking the help of network-specific communication protocols. Now, the communication could be anything from passing a single argument to requesting a piece of information or collaborating for multiple services.

Primarily, SOA emphasizes on the development of individual functions as carried out by each component in a standalone environment. It could be anything from validating a payment or allowing third-party sign-in.

It is evident that service-oriented architecture is not about modularizing an application but connecting or combining different services to build an app. In simple terms, service-oriented architecture is more about rendering a service, disregarding the fact, how.

You can also consider them to be the simplified version of microservices. They are loosely coupled and use enterprise bus messaging protocol to initiate communication between two services.

As per Gartner:

“SOA reduces redundancy and increases usability, maintainability, and value. This produces interoperable, modular systems that are easier to use and maintain. SOA creates simpler and faster systems that increase agility and reduce total cost of ownership (TCO).”

A well-crafted SOA increases agility over time.

Salient features of SOA

• SOA is a coarsely grained form of a monolithic application.
• SOA uses the IP network to communicate and connect with distinct services.
• SOA supports multiple message protocols like AMQP, MSMQ, and SOAP.

Microservices

Microservices, as a generic term, is kind of a software development methodology that focuses on developing modules or smaller chunks of an application. Later, these can be deployed independently within any application, and communicate with the help of the APIs. Unlike, service-oriented architecture, one that uses the enterprise-level messaging protocol, particularly, the IP, microservices induce APIs to connect with distinct modules.

To put it this way, microservices allow developers to create smaller services and then combine each to cohesively work as a single application. Where developing the entire application as a single standalone concept appears a lot fussy, microservices eases the task of the developer enabling them to work on separate modules independently and then integrate all the services to form the app.

Each module or the service built is capable of running its own process. These services can be integrated with any other service making use of lightweight protocols, called API. It is these APIs that enable the two microservices to communicate with each other.

For instance, consider you have a Healthcare Portal and you want to add an authentication page. What you can do is create a distinct application that is solely dedicated to doing authentication and then integrates the same within the existing infrastructure using any kind of communication protocol.

Salient Features of Microservices

• Microservices eliminate the concept of centralized governance.
• Allow developers to build smaller modules that can run independently.
• Allow teams to work separately on distinct services and then recombine them as and when needed.
• Microservices are granulated SOA.
• Microservices are, generally, deployed in containers.

When we look at the three together, we know that APIs are protocols or standards used by developers to initiate communication between two services or applications.

Major Differences — SOA Vs Microservices

• SOA is service driven and focuses on maximizing service reusability. On the contrary, microservices follow a decentralized approach, where the entire application is decoupled in separate components and each component can be used separately in a standalone environment.
• SOA makes use of the enterprise bus messaging protocol to promote communication between the two intervening parties, whereas microservices, remaining a step ahead, use APIs to communicate between two components.
• SOA aims to enhance the reusability of an application, following the share as much as possible approach. While reusability is possible for microservices too, it promotes decoupling components to build distinct applications, following a share as little as a possible approach.
• For SOA, any change or modification in the application requires updating the entire monolith. But for organizations that deploy microservices, a new feature calls for new service integration.
• SOA makes use of multiple messaging protocols whereas microservices are more inclined towards the security aspect and hence, embed lightweight protocols such as APIs, https, etc.
• Services that share the same data storage are vulnerable to data leaks. Microservices, on the other hand, deploy independent databases for each application, maintaining the integrity of the information stored. In addition, this also helps with performance and scale.
• SOA promotes sharing multiple components which leads to the creation of data dependency. Microservices couple each component into a single unit, which is independent. This quickens or enhances the speed of the system built using microservices. This, of course, is a big drawback for organizations investing in SOA. In turn, microservices have a better time to market advantages.
• Microservices are smaller components and each is designed to cover up a single purpose. An SOA is bigger in size and the components involved cater to more than one function. Microservices being smaller components makes it more maintainable.

Summing It Up

It is evident that microservices are the finest form of SOA and use APIs to communicate with each other. It would not be wrong to state that an API is a crucial element of microservices. It is only with the help of APIs that two microservices communicate with each other to build the final application.

In short microservices focus on what do you want to solve? Employing the microservices kind of architecture, you would need the right set of strategies as decomposing the application into a microservice-based application isn’t easy, let alone defining it.

The choice of architecture is better suited to the requirements of the project. For applications that mandate complex elements with varied structural components, SOA serves the purpose. On the other hand, for instances where developers seek a better hold at their development process, segmenting applications into smaller chunks, microservices lead the charge.

Each has its own set of features and custom-fit to map a particular requirement. And so it is the application that determines which architecture would benefit the development process.

Further Reading

API vs. Microservices: A Microservice Is More Than Just an API