SOA and microservices have much in common and at first sight, it seems that the latter is just a new hyped buzzword for what SOA has already described. Yet, there are some differences between both.
What are Microservices?
Let´s first look at what a microservice is. Although there is no common definition for what a microservice is, there are a couple of common characteristics that definitions of microservices share. Those are:
1) Microservices are small, individual and independent components of software that, together, make an application.
2) Microservices are business-oriented, which means that the software architecture focuses on business purposes, such as a business capability, a particular product or service.
3) Every microservice provides a small piece of software to a greater purpose. Therefore, microservices regularly communicate with each other when in operation.
4) A major purpose of microservices is that they can be developed and deployed independently from each other. This leads to a decentralization of development teams in practice, which enables them to develop and deploy faster and with less dependencies and constraints.
5) Due to the modular architecture and the increased amount of communication interfaces between the microservices, errors and failures can be analyzed more precisely. In addition, microservice architectures are usually designed in such a way that they still function in the case that single microservices provide errors.
6) A microservices architecture is often used in areas that are continuously developed further. In such environments, the advantages of independent development and deployment, as well as failure tolerance is of highest importance.
What is Service Oriented Architecture (SOA)?
SOA, which stands for Service Oriented Architecture, is a software architecture style where generic services are provided to other components in the same architecture that provide more complex services based on the shared generic services. In the end, it is similar to a company´s shared services center.
Let´s imagine the following situation: A company that is operating in different countries has no shared services center at the moment. Therefore, basic HR and Finance activities, such as payroll and accounting are done individually in every country. By implementing a shared services center, the company can send all requests related to those activities to one single point of contact where the activities are executed. When the task is finalized, the results are sent back to the individual country. The individual countries then use the results, adapt them to country rules or their individual workforce and provide an additional, more sophisticated, or more individual service to their customers. SOA works in a very similar way. It allows to extract basic services from individual applications and bundles them in a shared services module instead. This shared services module then executes the tasks and provides the results back to the individual applications, which use them further.
So let´s investigate what SOA and microservices have in common and what not.
What do Microservices and SOA have in Common?
- Both enable an integration into the wider IT – in contrast to monolithic systems that have no integration outside their own boundaries. A monolithic system can be the better option in areas where security is highly important or where there are no synergies with other systems expected, however, with the broad adoption of cloud technology and the required scalability, integrated systems are usually the preferred solution for architects
- Both try to identify independent pieces of software that can be applied in different contexts and environments. SOA does this with the help of services that deliver information from one to another system and microservices do this with APIs that provide standardized interfaces for communication
- SOA can have very different scopes, from very small to very big. Unlike the name suggests, this is also true for microservices, which can be just the authentication of a user at a service or the full purchase process behind your e-commerce basket
What are the Differences Between Microservices and SOA?
- The objective of SOA is to design systems as a set of loosely coupled services that enable the integration of applications. On the contrary, microservices have the objective to work on different platforms and in different environments that emerged due to the manifold cloud environments and mobile solutions that require to work on different operating systems.
- SOA is not dynamic and cannot fit for different purposes. They must be adapted or redeveloped every time a critical architecture piece of the involved technology changes. On the contrary, microservices try to be more independent by building on standardized interfaces that are valid across different technologies. However, there are often different standards, which can in the end lead to the same challenge that SOA has.
- SOA typically shares fundamental components across different services. On the contrary, microservices usually have everything they need within the service, duplicated in every single microservice. Microservices are hence a bit slower, but less dependent on underlying services in order to work.
SOA and microservices are quite similar concepts. Some might also argue that microservices are a particular type of SOA. In the end, SOA and microservices both have their purposes. SOA helps to interconnect large enterprise systems (e.g. an HR or ERP system) so that they can communicate and interchange data. In contrast to that, microservices have the goal to work in different environments and independent from those environments, such as on web-based systems, operating systems, or cloud environments.