Welcome!

Microservices Expo Authors: Elizabeth White, Liz McMillan, Gopala Krishna Behara, Sridhar Chalasani, Tirumala Khandrika

Related Topics: Microservices Expo

Microservices Expo: Article

Exclusive SOA Web Services Journal Briefing – Thomas Erl On SOA

The Principles of Service-Orientation

With the unwavering prominence of service-oriented architecture (SOA) there is an increasing interest in understanding what exactly it means for something to be considered "service-oriented." Thomas Erl recently completed a lengthy research project for SOA Systems Inc. into the origins of SOA and the current state of service-orientation among all primary SOA technology platforms. This body of work contributed to the mainstream SOA methodology developed by SOA Systems and was also documented in Thomas's new book, Service-Oriented Architecture: Concepts, Technology, and Design. We caught up with Thomas (a previous contributor to WSJ) to ask him to share some of the insights he gained from his work with SOA and service-orientation.

There's no need to mention that SOA has become a major focal point of the IT industry and a primary consideration on numerous corporate agendas. Nor is there a need to get into how SOA has been so heavily promoted that the term has already reached hall-of-fame status as one of the most recognized acronyms in IT history.

What is more important than the term itself is the impact its perceived meaning continues to have on how automation solutions are constructed. Its popularity to date is largely the result of vendors advertising SOA support or capability as part of their product lines. Because SOA has been so vendor-driven, its meaning has been somewhat divergent, skewed by proprietary technology that is still identified with common characteristics that transcend proprietary boundaries.

These common characteristics are critical to defining and understanding an abstract technology architecture classified as "service-oriented." Viewing SOA in abstract is what establishes an agnostic reference point from which proprietary implementations can be measured and, ultimately, unified.

Vendor-Oriented Service-Orientation
Vendors and other organizations in the SOA space have published numerous papers, blueprints, and even frameworks. Most such documents serve the dual purpose of educating readers about SOA while marketing related products or services. This is nothing new. Past variations of client-server and distributed architecture models have varied significantly in both technology and design, depending mostly on who and what was used to implement them.

However, because a core expectation of SOA is its ability to harmonize and streamline diverse technical environments, preserving an abstract viewpoint is required to achieving its potential. This is because SOA, when elevated to an enterprise level, can be used to establish an ecosystem in which an agnostic, overarching framework transcends proprietary environments and constraints.

How the components and elements within this framework are shaped and standardized is of critical importance. This underlines the need for a design paradigm that is sufficiently generic so that it can be applied to solutions regardless of implementation, while remaining in alignment with where powerhouse vendors and organizations are currently taking the technology that is fueling the service-oriented computing platform.

Service-Orientation and Object-Orientation
Design paradigms have played an important role in the evolution of technology and application architecture. The most widely recognized paradigm for distributed business automation has been object-orientation. The system-wide implementation technology for object-oriented solutions has traditionally been proprietary, where, despite the use of the agnostic principles of object-orientation, objects or components are designed to function and interact by using technology and protocols specific to a computing and/or vendor platform.

Service-orientation owes much of its existence to object-orientation. Like traditional multitiered architectures, SOA is based on a model wherein solution logic is distributed. As with object-orientation, concepts such as encapsulation, abstraction, and reusability are fundamental to the design of distributed units of automation logic (services) within SOA. Key differences in these approaches are focused on how these units relate to each other and the scope at which the respective paradigms can be applied.

See Figure 1

Service-Orientation and the Separation of Concerns
I have yet to find a better means of explaining service-orientation than to reach back to that fundamental software engineering theory known as the "separation of concerns." This theory essentially proposes that larger problems be decomposed into a series of individually identifiable problems or "concerns." The logic required to address or solve the larger problem can then also be broken down into individual units of logic that address specific concerns.

Past design paradigms and development platforms have applied this theory in different ways. Component-based and object-oriented designs, for example, provide specific approaches for the decomposition of concerns and the design of corresponding solution logic. Service-orientation establishes a new and distinct means of realizing a separation of concerns. As a design paradigm, it is an evolution of past approaches, augmented and extended in support of the overall goals and characteristics of SOA.

See Figure 2

Common Service-Orientation Principles
Service-orientation began with a modest scope - a basic set of principles centered on an architectural model focused primarily on distinguishing services as reusable and discoverable resources. However, technology architecture in support of service-orientation is making significant strides, and extending its reach into key realms of enterprise computing.

Expectations are being raised surrounding a new era of business automation composed of services as adaptive, shared software assets that promise to infuse an enterprise with organization-level agility, federated interoperability, and vendor independence. These expectations have placed demands on what a distributed automation solution classified as "service-oriented" should be capable of, expanding the breadth of the service-oriented paradigm and adding to and further shaping its principles.

So far, eight common and fundamental principles have been identified. Note that these are classified as "common" in that they represent a cross-section of the most widely accepted design approaches and best practices promoted and practiced by the organizations most responsible for realizing the contemporary SOA movement.

Here then are the common principles of service-orientation:

  • services are loosely coupled
  • services share a formal contract
  • services abstract underlying logic
  • services are composable
  • services are reusable
  • services are autonomous
  • services are stateless
  • services are discoverable

More Stories By Thomas Erl

Thomas Erl is a best-selling IT author and founder of Arcitura Education Inc., a global provider of vendor-neutral educational services and certification that encompasses the Cloud Certified Professional (CCP) and SOA Certified Professional (SOACP) programs from CloudSchool.com™ and SOASchool.com® respectively. Thomas has been the world's top-selling service technology author for nearly a decade and is the series editor of the Prentice Hall Service Technology Series from Thomas Erl, as well as the editor of the Service Technology Magazine. With over 175,000 copies in print world-wide, his eight published books have become international bestsellers and have been formally endorsed by senior members of many major IT organizations and academic institutions. To learn more, visit: www.thomaserl.com

Comments (3)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Microservices Articles
Kubernetes is a new and revolutionary open-sourced system for managing containers across multiple hosts in a cluster. Ansible is a simple IT automation tool for just about any requirement for reproducible environments. In his session at @DevOpsSummit at 18th Cloud Expo, Patrick Galbraith, a principal engineer at HPE, discussed how to build a fully functional Kubernetes cluster on a number of virtual machines or bare-metal hosts. Also included will be a brief demonstration of running a Galera MyS...
Your homes and cars can be automated and self-serviced. Why can't your storage? From simply asking questions to analyze and troubleshoot your infrastructure, to provisioning storage with snapshots, recovery and replication, your wildest sci-fi dream has come true. In his session at @DevOpsSummit at 20th Cloud Expo, Dan Florea, Director of Product Management at Tintri, provided a ChatOps demo where you can talk to your storage and manage it from anywhere, through Slack and similar services with...
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Day 2 Keynote at 17th Cloud Expo, Sandy Ca...
New competitors, disruptive technologies, and growing expectations are pushing every business to both adopt and deliver new digital services. This ‘Digital Transformation’ demands rapid delivery and continuous iteration of new competitive services via multiple channels, which in turn demands new service delivery techniques – including DevOps. In this power panel at @DevOpsSummit 20th Cloud Expo, moderated by DevOps Conference Co-Chair Andi Mann, panelists examined how DevOps helps to meet the de...
As Enterprise business moves from Monoliths to Microservices, adoption and successful implementations of Microservices become more evident. The goal of Microservices is to improve software delivery speed and increase system safety as scale increases. Documenting hurdles and problems for the use of Microservices will help consultants, architects and specialists to avoid repeating the same mistakes and learn how and when to use (or not use) Microservices at the enterprise level. The circumstance w...
"NetApp's vision is how we help organizations manage data - delivering the right data in the right place, in the right time, to the people who need it, and doing it agnostic to what the platform is," explained Josh Atwell, Developer Advocate for NetApp, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
TCP (Transmission Control Protocol) is a common and reliable transmission protocol on the Internet. TCP was introduced in the 70s by Stanford University for US Defense to establish connectivity between distributed systems to maintain a backup of defense information. At the time, TCP was introduced to communicate amongst a selected set of devices for a smaller dataset over shorter distances. As the Internet evolved, however, the number of applications and users, and the types of data accessed and...
DevOps is often described as a combination of technology and culture. Without both, DevOps isn't complete. However, applying the culture to outdated technology is a recipe for disaster; as response times grow and connections between teams are delayed by technology, the culture will die. A Nutanix Enterprise Cloud has many benefits that provide the needed base for a true DevOps paradigm. In their Day 3 Keynote at 20th Cloud Expo, Chris Brown, a Solutions Marketing Manager at Nutanix, and Mark Lav...
The Software Defined Data Center (SDDC), which enables organizations to seamlessly run in a hybrid cloud model (public + private cloud), is here to stay. IDC estimates that the software-defined networking market will be valued at $3.7 billion by 2016. Security is a key component and benefit of the SDDC, and offers an opportunity to build security 'from the ground up' and weave it into the environment from day one. In his session at 16th Cloud Expo, Reuven Harrison, CTO and Co-Founder of Tufin, ...
Gone are the days when application development was the daunting task of the highly skilled developers backed with strong IT skills, low code application development has democratized app development and empowered a new generation of citizen developers. There was a time when app development was in the domain of people with complex coding and technical skills. We called these people by various names like programmers, coders, techies, and they usually worked in a world oblivious of the everyday pri...