Microservices

In computing, microservices are small, independent processes that communicate with each other to form complex applications which utilize language-agnostic APIs.[1] These services are small building blocks, highly decoupled and focused on doing a small task,[2][3][4] facilitating a modular approach to system-building.[5] The microservices architectural style is becoming the standard for building continuously deployed systems. [6]

Details

Properties of microservices architecture (MSA):

A microservices-based architecture

History

Dr. Peter Rodgers introduced the term "Micro-Web-Services" during a presentation at Cloud Computing Expo in 2005. On slide #4 of the conference presentation he states that "Software components are Micro-Web-Services". Juval Löwy had similar precursor ideas about classes being granular services, as the next evolution of Microsoft architecture. "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 interface. Any service, at any granularity, can be exposed." He described how a well-designed service platform "applies the underlying architectural principles of the Web and Web services together with Unix-like scheduling and pipelines to provide radical flexibility and improved simplicity by providing a platform to apply service-oriented architecture throughout your application environment". [7] The design, which originated in a research project at Hewlett Packard Labs, aims to make code less brittle and to make large-scale, complex software systems robust to change.[8] To make "Micro-Web-Services" work one has to question and analyze the foundations of architectural styles( such as SOA) and the role of messaging between software components in order to arrive at a new general computing abstraction.[9] In this case, one can think of resource-oriented computing (ROC) as a generalized form of the Web abstraction. If in the Unix abstraction "everything is a file", then in ROC everything is a "Micro-Web-Service". It can contain information, code or the results of computations so that a service can be either a consumer or producer in a symmetrical and evolving architecture.

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 these ideas as a case study in March 2012 at 33rd Degree in Kraków in Microservices - Java, the Unix Way, as did Fred George about the same time. Adrian Cockcroft at Netflix, describing 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.[10]

Philosophy

Philosophy of microservices architecture essentially equals the Unix philosophy of "Do one thing and do it well". It is described as follows:[11][12][13]

Criticism

The microservices architecture is subject to criticism for a number of issues:

Speaking of complexity, it is also true that an application made up of any number of microservices has to access its respective ecosystem which is riddled with unnecessary complexity.[17] This kind of complexity can be reduced by standardizing the access mechanism. The Web as a system handles this element very well. It retained essentially the same access mechanism between browser and application resource over the last 20 years. Using the number of Web pages indexed by Google it grew from 26 million pages in 1998 to around 60 trillion individual pages by 2015 without the need to change its access mechanism. The Web itself is the best example that the complexity inherent in traditional monolithic software systems can be overcome.[18][19]

Nanoservices

Too-fine-grained microservices have been criticized as an anti-pattern, dubbed a nanoservice by Arnon Rotem-Gal-Oz:

[A] nanoservice is an anti-pattern where a service is too fine grained. [A] nanoservice is a service whose overhead (communications, maintenance etc.) outweighs its utility.[20][21][lower-alpha 1]

Problems include the code overhead (interface definition, retries), runtime overhead (serialization/deserialization, network traffic), and fragmented logic (useful functionality not implemented in one place, instead requiring combining many services).

Proposed alternatives to nanoservices include:[21]

Languages

Users

Known users of the Microservices architecture:

Implementations

See also

Notes

  1. ↑ Spelling and grammar corrected.

References

  1. 1 2 3 4 5 Martin Fowler. "Microservices".
  2. ↑ Sam Newman. Building Microservices. ISBN 978-1-4919-5035-7.
  3. ↑ Eberhard Wolff. Microservices - Flexible Software Architectures. ISBN 978-1-5233-6125-0.
  4. ↑ Eberhard Wolff. Microservices Primer - A Short Overview. ISBN 978-1-5234-7213-0.
  5. ↑ Miller, Joseph B. (2014). Internet Technologies and Information Services. Library and Information Science Text Series (2 ed.). ABC-CLIO. p. 269. ISBN 9781610698863. Retrieved 2015-08-04. As with many complex information technologies, there are two general architectural options: a monolithic, layered system that embodies all the needed functionalities within one large-scale solution or a modular approach based on microservice architecture (MSA). [...] MSA is a more flexible, modular strategy.
  6. ↑ Balalaie, A.; Heydarnoori, A.; Jamshidi, P. (2016-05-01). "Microservices Architecture Enables DevOps: Migration to a Cloud-Native Architecture". IEEE Software 33 (3): 42–52. doi:10.1109/MS.2016.64. ISSN 0740-7459.
  7. ↑ Rodgers, Peter. "Service-Oriented Development on NetKernel- Patterns, Processes & Products to Reduce System Complexity". CloudComputingExpo. http://sys-contv.sys-con.com. Retrieved 19 August 2015. External link in |publisher= (help)
  8. ↑ Russell, Perry; Rodgers, Peter; Sellman, Royston (2004). "Architecture and Design of an XML Application Platform". HP Technical Reports. p. 62. Retrieved 20 August 2015.
  9. ↑ Hitchens, Ron (Dec 2014). Swaine, Michael, ed. "Your Object Model Sucks". PragPub Magazine (Pragmatic Programmers): 15.
  10. ↑ James Lewis and Martin Fowler. "Microservices".
  11. ↑ Lucas Krause. Microservices: Patterns and Applications. ASIN B00VJ3NP4A.
  12. ↑ Lucas Krause. "Philosophy of Microservices?".
  13. 1 2 Jim Bugwadia. "Microservices: Five Architectural Constraints".
  14. ↑ Jan Stenberg (11 August 2014). "Experiences from Failing with Microservices".
  15. 1 2 3 "Developing Microservices for PaaS with Spring and Cloud Foundry".
  16. ↑ Robert Annett. "Where is the complexity?".
  17. ↑ "BRASS Building Resource Adaptive Software Systems". U.S. Government. DARPA. April 7, 2015. "Access to system components and the interfaces between clients and their applications, however, are mediated via a number of often unrelated mechanisms, including informally documented application programming interfaces (APIs), idiosyncratic foreign function interfaces, complex ill-understood model definitions, or ad hoc data formats. These mechanisms usually provide only partial and incomplete understanding of the semantics of the components themselves. In the presence of such complexity, it is not surprising that applications typically bake-in many assumptions about the expected behavior of the ecosystem they interact with."
  18. ↑ Alpert, Jesse; Hajaj, Nissan. "We knew the web was big". Official Google Blog. Google.com. Retrieved 22 August 2015.
  19. ↑ "The Story". How search works. Google.com. Retrieved 22 August 2015.
  20. ↑ Services, Microservices, Nanoservices – oh my!, Arnon Rotem-Gal-Oz
  21. 1 2 Pratical SOA: 1.1: Nanoservices, Arnon Rotem-Gal-Oz, 2010
  22. ↑ "Jolie".
  23. ↑ "How Enterprise PaaS can add Critical Value to Microservices".
  24. ↑ "Microservices" (PDF).
  25. ↑ "Microservices".
  26. ↑ "NodeCrunch Tag Archives: microservices".
  27. ↑ "Schedule Thursday (3rd Dec.) - conference". gotocon.com. Retrieved 2016-04-19.
  28. ↑ "Products > Platform". 1060 Research Ltd. Retrieved 12 October 2015.
  29. ↑ Wilma documentation
  30. ↑ Wilma source code
  31. ↑ "Vertx".
  32. ↑ "Baratine".
  33. ↑ "KumuluzEE".

Further reading

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