Microservices

Definition of Microservices

Microservices - also known as the microservice architecture - is an architectural style that structures an [[Application}application]] as a collection of services that are:

• Highly maintainable and testable
• Loosely coupled
• Independently deployable
• Organized around business capabilities
• Owned by a small team

The microservice architecture enables the rapid, frequent and reliable delivery of large, complex applications. It also enables an organization to evolve its technology stack.

source: DZone

The microservice architecture is not a silver bullet. It has several drawbacks. Moreover, when using this architecture there are numerous issues that you must address. The microservice architecture pattern language is a collection of patterns for applying the microservice architecture. It has two goals:

• The pattern language enables you to decide whether microservices are a good fit for your application.
• The pattern language enables you to use the microservice architecture successfully.

A good starting point is the Monolithic Architecture pattern, which is the traditional architectural style that is still a good choice for many applications. It does, however, have numerous limitations and issues and so a better choice for large/complex applications is the Microservice architecture pattern.

What Microservices are Not

Microservices might also be understood by what they are not. The two comparisons drawn most frequently with microservices architecture are monolithic architecture and service-oriented architecture (SOA).

The difference between microservices and monolithic architecture is that microservices compose a single application from many smaller, loosely coupled services as opposed to the monolithic approach of a large, tightly coupled application

The differences between microservices and SOA can be a bit less clear. While technical contrasts can be drawn between microservices and SOA, especially around the role of the [[Enterprise Service Bus (ESB)}enterprise service bus (ESB)]], it’s easier to consider the difference as one of scope. SOA was an enterprise-wide effort to standardize the way all web services in an organization talk to and integrate with each other, whereas microservices architecture is application-specific.

History of Microservices

There are numerous claims as to the origin of Micro services. Whilst Vice President of ThoughtWorks in 2004, Fred George began working on Micro Service prototype architectures based on what he called the "Baysean Principals" named after Jeff Bay.

As early as 2005, Peter Rodgers introduced the term "Micro-Web-Services" during a presentation at the Web Services Edge conference. Against conventional thinking and at the height of the SOAP SOA architecture hype curve he argued for "REST-services" and on slide #4 of the conference presentation, he discusses "Software components are Micro-Web-Services". He goes on to say "Micro-Services are composed using Unix-like pipelines (the Web meets Unix = true loose-coupling). Services can call services (+multiple language run-times). Complex service-assemblies are abstracted behind simple URI interfaces. Any service, at any granularity, can be exposed." He described how a well-designed microservices platform "applies the underlying architectural principles of the Web and REST services together with Unix-like scheduling and pipelines to provide radical flexibility and improved simplicity in service-oriented architectures.

Rodgers' work originated in 1999 with the Dexter research project at Hewlett Packard Labs, whose aim was to make code less brittle and to make large-scale, complex software systems robust to change. Ultimately this path of research led to the development of resource-oriented computing (ROC), a generalized computation abstraction in which REST is a special subset.

In 2007, Juval Löwy in his writing and speaking called for building systems in which every class was a service. Löwy realized this required the use of a technology that can support such granular use of services, and he extended Windows Communication Foundation (WCF) to do just that, taking every class and treating it as a service while maintaining the conventional programming model of classes.

A workshop of software architects held near Venice in May 2011 used the term "microservice" to describe what the participants saw as a common architectural style that many of them had been recently exploring. In May 2012, the same group decided on "microservices" as the most appropriate name. James Lewis presented some of those ideas as a case study in March 2012 at 33rd Degree in Kraków in Micro services - Java, the Unix Way, as did Fred George about the same time. Adrian Cockcroft, former director for the Cloud Systems at Netflix, described this approach as "fine grained SOA", pioneered the style at web scale, as did many of the others mentioned in this article - Joe Walnes, Dan North, Evan Bottcher, and Graham Tackley.

Microservices is a specialization of an implementation approach for service-oriented architectures (SOA) used to build flexible, independently deployable software systems. The microservices approach is a first realization of SOA that followed the introduction of DevOps and is becoming more popular for building continuously deployed systems.

In February 2020, the Cloud Microservices Market Research Report predicted that the global microservice architecture market size will increase at a CAGR of 21.37% from 2019 to 2026 and reach $3.1 billion by 2026.