Click here to close now.

Welcome!

@MicroservicesE Blog Authors: Pat Romanski, Elizabeth White, Michael Kanasoot, Liz McMillan, Hovhannes Avoyan

Related Topics: @MicroservicesE Blog

@MicroservicesE Blog: Article

SOA Pattern of the Week (#1): Service Façade

Functional and behavioral changes to core business logic

One of the fundamental goals when designing service-oriented solutions is to attain a reduced degree of coupling between services, thereby increasing the freedom and flexibility with which services can be individually evolved. Achieving the right level of coupling "looseness" is most often considered a design issue that revolves around the service contract and the consumer programs that form dependencies upon it.

However, for the service architect there are opportunities to establish intermediate layers of abstraction within the service implementation that further foster reduced levels of coupling between its internal moving parts so as to accommodate the evolution and governance of the service itself. These intermediate abstraction layers are created by the application of Service Façade, a design pattern focused on intra-service design.

When designing a service, there are several negative coupling types you need to look out for. Contract-to-logic coupling, for example, results in a service contract that is derived from (and therefore may have formed dependencies upon) the underlying service logic, which makes the contract subject to change whenever the logic changes. The result is, predictably, a cascading effect whereby all service consumers are impacted (usually negatively) by the changes.

Service Façade can help avoid these situations by establishing an intermediary processing layer in between the core service logic and the service contract. The façade logic allows the service contract to remain decoupled from the underlying logic and further shields it from changes to the core business logic. This applies to both functional and behavioral changes, the latter of which may (often inadvertently) come about as a result of applying the Service Refactoring pattern. The façade layer can compensate for internal changes so that the service contract does not need to be modified as a result of the changes and/or the behavior of the functionality expressed in the contract is also not affected. In both cases, the service can evolve internally while existing service consumers remain protected from any potential side-effects.

Another scenario that can be effectively managed through the application of this pattern is when a single body of core service logic requires multiple contracts (a situation that actually pertains to another pattern called Concurrent Contracts). In this case, a separate service façade component can be created for each service contract, thereby retaining a clean abstraction of core service logic from the contract layer. This avoids having to augment and bloat the core service logic over time in order to accommodate different contracts and can further leverage the aforementioned benefits of functional and behavioral compensation when that logic is subject to functional change or refactoring efforts.

The Service Façade pattern can result in an elegant service architecture with clean layers of abstraction, but it can also impose extra processing overhead that naturally comes with increasing the physical distribution of service logic. The fact that service logic ends up being more distributed can also be perceived as increasing the complexity of the service design as well. Carefully minding the type of logic placed in façade layers will help mitigate these issues.

Overall, though, the intelligent and regulated application of this pattern can result in an effective separation of intra-service processing responsibilities, which brings with it numerous governance benefits that can accommodate the long-term evolution of the service and further help to preserve on-going relationships formed with service consumer programs.

The SOA Pattern of the Week series is comprised of original content and insights provided courtesy of the authors and contributors of the SOAPatterns.org community site and the book "SOA Design Patterns" (Erl et al., ISBN: 0136135161, Prentice Hall, 2009), the latest title in the "Prentice Hall Service-Oriented Computing Series from Thomas Erl" (www.soabooks.com). Copyright 2009 SOA Systems Inc.

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

More Stories By Herbjorn Wilhelmsen

Herbjorn Wilhelmsen is an Architect and Senior Consultant at Objectware in Stockholm, Sweden. His main focus areas include service-oriented architecture, Web services and business architecture. Herbjörn has many years of industry experience working as a developer, development manager, architect and teacher in several fields of operations, such as telecommunications, marketing, payment industry, health care and public services. He is active as an author in the Prentice Hall Service-Oriented Computing Series from Thomas Erl and has contributed design patterns to SOAPatterns.org. He leads the Business-to-IT group in the Swedish chapter of the International Association of Software Architects, which performs a comparative study of a number of business architecture methodologies. Herbjörn holds a Bachelor of Science from Stockholm University.

Comments (0)

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.


@MicroservicesExpo Stories
The speed of product development has increased massively in the past 10 years. At the same time our formal secure development and SDL methodologies have fallen behind. This forces product developers to choose between rapid release times and security. In his session at DevOps Summit, Michael Murray, Director of Cyber Security Consulting and Assessment at GE Healthcare, examined the problems and presented some solutions for moving security into the DevOps lifecycle to ensure that we get fast AND ...
Software is eating the world. Companies that were not previously in the technology space now find themselves competing with Google and Amazon on speed of innovation. As the innovation cycle accelerates, companies must embrace rapid and constant change to both applications and their infrastructure, and find a way to deliver speed and agility of development without sacrificing reliability or efficiency of operations. In her Day 2 Keynote DevOps Summit, Victoria Livschitz, CEO of Qubell, discussed...
SYS-CON Events announced today that MetraTech, now part of Ericsson, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Ericsson is the driving force behind the Networked Society- a world leader in communications infrastructure, software and services. Some 40% of the world’s mobile traffic runs through networks Ericsson has supplied, serving more than 2.5 billion subscribers.
How does one bridge the gap between traditional enterprise storage infrastructures and the private, hybrid, and public cloud? In his session at 15th Cloud Expo, Dan Pollack, Chief Architect of Storage Operations at AOL Inc., examed the workload differences and required changes to reuse existing knowledge and components when building and using a cloud infrastructure. He also looked into the operational considerations, tool requirements, and behavioral changes required for private cloud storage s...
Many people recognize DevOps as an enormous benefit – faster application deployment, automated toolchains, support of more granular updates, better cooperation across groups. However, less appreciated is the journey enterprise IT groups need to make to achieve this outcome. The plain fact is that established IT processes reflect a very different set of goals: stability, infrequent change, hands-on administration, and alignment with ITIL. So how does an enterprise IT organization implement change...
Working with Big Data is challenging, especially when decision makers depend on market insights and intelligence from your data but don't have quick access to it or find it unusable. In their session at 6th Big Data Expo, Ian Khan, Global Strategic Positioning & Brand Manager at Solgenia; Zel Bianco, President, CEO and Co-Founder of Interactive Edge of Solgenia; and Ermanno Bonifazi, CEO & Founder at Solgenia, discussed how a revolutionary cloud-based BI along with mobile analytics is already c...
Hardware will never be more valuable than on the day it hits your loading dock. Each day new servers are not deployed to production the business is losing money. While Moore's Law is typically cited to explain the exponential density growth of chips, a critical consequence of this is rapid depreciation of servers. The hardware for clustered systems (e.g., Hadoop, OpenStack) tends to be significant capital expenses. In his session at Big Data Expo, Mason Katz, CTO and co-founder of StackIQ, disc...
There is no question that the cloud is where businesses want to host data. Until recently hypervisor virtualization was the most widely used method in cloud computing. Recently virtual containers have been gaining in popularity, and for good reason. In the debate between virtual machines and containers, the latter have been seen as the new kid on the block – and like other emerging technology have had some initial shortcomings. However, the container space has evolved drastically since coming on...
T-Mobile has been transforming the wireless industry with its “Uncarrier” initiatives. Today as T-Mobile’s IT organization works to transform itself in a like manner, technical foundations built over the last couple of years are now key to their drive for more Agile delivery practices. In his session at DevOps Summit, Martin Krienke, Sr Development Manager at T-Mobile, will discuss where they started their Continuous Delivery journey, where they are today, and where they are going in an effort ...
The 4th International Internet of @ThingsExpo, co-located with the 17th International Cloud Expo - to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA - announces that its Call for Papers is open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
Python is really a language which has swept the scene in recent years in terms of popularity, elegance, and functionality. Research shows that 8 out 10 computer science departments in the U.S. now teach their introductory courses with Python, surpassing Java. Top-ranked CS departments at MIT and UC Berkeley have switched their introductory courses to Python. And the top three MOOC providers (edX, Coursera, and Udacity) all offer introductory programming courses in Python. Not to mention, Python ...
Enterprises are fast realizing the importance of integrating SaaS/Cloud applications, API and on-premises data and processes, to unleash hidden value. This webinar explores how managers can use a Microservice-centric approach to aggressively tackle the unexpected new integration challenges posed by proliferation of cloud, mobile, social and big data projects. Industry analyst and SOA expert Jason Bloomberg will strip away the hype from microservices, and clearly identify their advantages and d...
SYS-CON Events announced today that SUSE, a pioneer in open source software, will exhibit at SYS-CON's DevOps Summit 2015 New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. SUSE provides reliable, interoperable Linux, cloud infrastructure and storage solutions that give enterprises greater control and flexibility. More than 20 years of engineering excellence, exceptional service and an unrivaled partner ecosystem power the products and support that help ...
"People are a lot more knowledgeable about APIs now. There are two types of people who work with APIs - IT people who want to use APIs for something internal and the product managers who want to do something outside APIs for people to connect to them," explained Roberto Medrano, Executive Vice President at SOA Software, in this SYS-CON.tv interview at Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that O'Reilly Media has been named “Media Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York City, NY. O'Reilly Media spreads the knowledge of innovators through its books, online services, magazines, and conferences. Since 1978, O'Reilly Media has been a chronicler and catalyst of cutting-edge development, homing in on the technology trends that really matter and spurring their adoption...
Bill Doerrfeld at Nordic APIs has written today about how APIs are evolving the B2B landscape. This is a particularly interesting article for me, because my personal background is working for an EDI provider, where I linked EDI processes from the private network to the Internet, over 15 years ago. Vordel was founded to allow new Web Services APIs to be used for B2B. Axway, a B2B software company, acquired Vordel in 2012 to link B2B with Web APIs. This caused a domino effect, with other API Manag...
Node.js and io.js are increasingly being used to run JavaScript on the server side for many types of applications, such as websites, real-time messaging and controllers for small devices with limited resources. For DevOps it is crucial to monitor the whole application stack and Node.js is rapidly becoming an important part of the stack in many organizations. Sematext has historically had a strong support for monitoring big data applications such as Elastic (aka Elasticsearch), Cassandra, Solr, S...

Let's just nip the conflation of these terms in the bud, shall we?

"MIcro" is big these days. Both microservices and microsegmentation are having and will continue to have an impact on data center architecture, but not necessarily for the same reasons. There's a growing trend in which folks - particularly those with a network background - conflate the two and use them to mean the same thing.

They are not.

One is about the application. The other, the network. T...

I read an insightful article this morning from Bernard Golden on DZone discussing the DevOps conundrum facing many enterprises today – is it better to build your own DevOps tools or go commercial? For Golden, the question arose from his observations at a number of DevOps Days events he has attended, where typically the audience is composed of startup professionals: “I have to say, though, that a typical feature of most presentations is a recitation of the various open source products and compo...
The 5th International DevOps Summit, co-located with 17th International Cloud Expo – being held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the...