Welcome!

Microservices Expo Authors: Liz McMillan, AppDynamics Blog, Pat Romanski, Elizabeth White, APM Blog

Related Topics: Microservices Expo

Microservices Expo: 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
Apache Hadoop is a key technology for gaining business insights from your Big Data, but the penetration into enterprises is shockingly low. In fact, Apache Hadoop and Big Data proponents recognize that this technology has not yet achieved its game-changing business potential. In his session at 19th Cloud Expo, John Mertic, director of program management for ODPi at The Linux Foundation, will explain why this is, how we can work together as an open data community to increase adoption, and the i...
DevOps and microservices are permeating software engineering teams broadly, whether these teams are in pure software shops but happen to run a business, such Uber and Airbnb, or in companies that rely heavily on software to run more traditional business, such as financial firms or high-end manufacturers. Microservices and DevOps have created software development and therefore business speed and agility benefits, but they have also created problems; specifically, they have created software sec...
Much of the value of DevOps comes from a (renewed) focus on measurement, sharing, and continuous feedback loops. In increasingly complex DevOps workflows and environments, and especially in larger, regulated, or more crystallized organizations, these core concepts become even more critical. In his session at @DevOpsSummit at 18th Cloud Expo, Andi Mann, Chief Technology Advocate at Splunk, showed how, by focusing on 'metrics that matter,' you can provide objective, transparent, and meaningful f...
Information technology is an industry that has always experienced change, and the dramatic change sweeping across the industry today could not be truthfully described as the first time we've seen such widespread change impacting customer investments. However, the rate of the change, and the potential outcomes from today's digital transformation has the distinct potential to separate the industry into two camps: Organizations that see the change coming, embrace it, and successful leverage it; and...
With the rise of Docker, Kubernetes, and other container technologies, the growth of microservices has skyrocketed among dev teams looking to innovate on a faster release cycle. This has enabled teams to finally realize their DevOps goals to ship and iterate quickly in a continuous delivery model. Why containers are growing in popularity is no surprise — they’re extremely easy to spin up or down, but come with an unforeseen issue. However, without the right foresight, DevOps and IT teams may lo...
SYS-CON Events announced today that Tintri Inc., a leading producer of VM-aware storage (VAS) for virtualization and cloud environments, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Tintri VM-aware storage is the simplest for virtualized applications and cloud. Organizations including GE, Toyota, United Healthcare, NASA and 6 of the Fortune 15 have said “No to LUNs.” With Tintri they mana...
Digitization is driving a fundamental change in society that is transforming the way businesses work with their customers, their supply chains and their people. Digital transformation leverages DevOps best practices, such as Agile Parallel Development, Continuous Delivery and Agile Operations to capitalize on opportunities and create competitive differentiation in the application economy. However, information security has been notably absent from the DevOps movement. Speed doesn’t have to negat...
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform and how we integrate our thinking to solve complicated problems. In his session at 19th Cloud Expo, Craig Sproule, CEO of Metavine, will demonstrate how to move beyond today's coding paradigm ...
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. Big Data at Cloud Expo - to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is...
The Jevons Paradox suggests that when technological advances increase efficiency of a resource, it results in an overall increase in consumption. Writing on the increased use of coal as a result of technological improvements, 19th-century economist William Stanley Jevons found that these improvements led to the development of new ways to utilize coal. In his session at 19th Cloud Expo, Mark Thiele, Chief Strategy Officer for Apcera, will compare the Jevons Paradox to modern-day enterprise IT, e...
Your business relies on your applications and your employees to stay in business. Whether you develop apps or manage business critical apps that help fuel your business, what happens when users experience sluggish performance? You and all technical teams across the organization – application, network, operations, among others, as well as, those outside the organization, like ISPs and third-party providers – are called in to solve the problem.
In his general session at 18th Cloud Expo, Lee Atchison, Principal Cloud Architect and Advocate at New Relic, discussed cloud as a ‘better data center’ and how it adds new capacity (faster) and improves application availability (redundancy). The cloud is a ‘Dynamic Tool for Dynamic Apps’ and resource allocation is an integral part of your application architecture, so use only the resources you need and allocate /de-allocate resources on the fly.
SYS-CON Events announced today the Kubernetes and Google Container Engine Workshop, being held November 3, 2016, in conjunction with @DevOpsSummit at 19th Cloud Expo at the Santa Clara Convention Center in Santa Clara, CA. This workshop led by Sebastian Scheele introduces participants to Kubernetes and Google Container Engine (GKE). Through a combination of instructor-led presentations, demonstrations, and hands-on labs, students learn the key concepts and practices for deploying and maintainin...
SYS-CON Events announced today the Enterprise IoT Bootcamp, being held November 1-2, 2016, in conjunction with 19th Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA. Combined with real-world scenarios and use cases, the Enterprise IoT Bootcamp is not just based on presentations but with hands-on demos and detailed walkthroughs. We will introduce you to a variety of real world use cases prototyped using Arduino, Raspberry Pi, BeagleBone, Spark, and Intel Edison. Y...
As applications are promoted from the development environment to the CI or the QA environment and then into the production environment, it is very common for the configuration settings to be changed as the code is promoted. For example, the settings for the database connection pools are typically lower in development environment than the QA/Load Testing environment. The primary reason for the existence of the configuration setting differences is to enhance application performance. However, occas...
If you’re responsible for an application that depends on the data or functionality of various IoT endpoints – either sensors or devices – your brand reputation depends on the security, reliability, and compliance of its many integrated parts. If your application fails to deliver the expected business results, your customers and partners won't care if that failure stems from the code you developed or from a component that you integrated. What can you do to ensure that the endpoints work as expect...
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 19th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo Silicon Valley Call for Papers is now open.
While DevOps promises a better and tighter integration among an organization’s development and operation teams and transforms an application life cycle into a continual deployment, Chef and Azure together provides a speedy, cost-effective and highly scalable vehicle for realizing the business values of this transformation. In his session at @DevOpsSummit at 19th Cloud Expo, Yung Chou, a Technology Evangelist at Microsoft, will present a unique opportunity to witness how Chef and Azure work tog...
When scaling agile / Scrum, we invariable run into the alignment vs autonomy problem. In short: you cannot have autonomous self directing teams if they have no clue in what direction they should go, or even shorter: Alignment breeds autonomy. But how do we create alignment? and what tools can we use to quickly evaluate if what we want to do is part of the mission or better left out? Niel Nickolaisen created the Purpose Alignment model and I use it with innovation labs in large enterprises to de...
Using new techniques of information modeling, indexing, and processing, new cloud-based systems can support cloud-based workloads previously not possible for high-throughput insurance, banking, and case-based applications. In his session at 18th Cloud Expo, John Newton, CTO, Founder and Chairman of Alfresco, described how to scale cloud-based content management repositories to store, manage, and retrieve billions of documents and related information with fast and linear scalability. He addres...