In SOA patterns, different application components interact with each other using a communication protocol over the network. Each service provides end-to-end functionality, for example, fetching an order history. SOA is widely adopted by large systems to integrate business processes, for example, taking your payment service from the main application and putting it as a separate solution.

In a general sense, SOAs take monolithic applications and spread some of those operations out into individual services that operate independently to each other. The goal of using an SOA is to loosen the coupling of your application's services.

Sometimes, an SOA includes not just splitting services apart from one another but splitting resources into separate instances of that service. For instance, while some choose to store all of their company's data in a single database split by tables, an SOA would consider modularizing the application by function into separate databases altogether. This allows you to scale and manage throughput based on the individual needs of tables for each database.

SOA has multiple benefits, for example, the parallelization of development, deployment, and operation. It decouples the service so that you can optimize and scale each service individually. However, it also requires more robust governance to ensure work performed by each service's team meets the same standard. With SOA, the solution could become complex enough to increase the overhead to balance that, so you need to make the right choice of tools and automation of service monitoring, deployment, and scaling.

There are multiple ways in which to implement SOA architecture. Here, you will learn about the Simple Object Access Protocol (SOAP) web service architecture and Representational State Transfer (REST) web service architecture.

Originally, SOAP was the most popular messaging protocol, but it is a bit heavyweight as it entirely relies on XML for data interchange. Now, REST architecture is becoming more popular as developers need to build more lightweight mobile and web applications. Let's learn about both architectures and their differences in more detail.