Welcome!

Websphere Authors: Gilad Parann-Nissany, Lori MacVittie, Yeshim Deniz, Srinivasan Sundara Rajan, Jason Bloomberg

Related Topics: Eclipse, SOA & WOA, Websphere

Eclipse: Article

The Case for Single-Purpose Services

Any service that is created needs to have a cleanly defined responsibility

Introduction
Services are useful, but they come with a price tag. The cost of developing a service is higher than the cost of developing a traditional (non-service-oriented) application, primarily due to the extra work and infrastructure required. Another common concern when creating and consuming services is the possibility of a performance hit. Together these issues hint that even if you've decided to wholeheartedly adopt SOA, you may not want or need to move all your functionality into services. This is where the application Service Encapsulation becomes a focal point as we need specific criteria to determine what should and should not be encapsulated into services.

To make this determination, we will take a look at three different aspects:

-- acceptable reasons for creating a service

-- costs associated with creating a service

-- and, of course, the performance issue

After covering these aspects specifically in relation to single-purpose services, I will introduce an implementation strategy.

Reasons to Create a Service
Any service that is created needs to have a cleanly defined responsibility. The capabilities it exposes should clearly fall within this defined responsibility. In the case of a single-purpose service, it can be argued that it may be better to implement single-purpose logic as a non-service-oriented application. Let's take a closer look at some of the more important considerations:

Reuse
When logic is incorporated into a service, it is potentially available for reuse by multiple applications, some of which may themselves be services. Reuse leads to reduced development and maintenance effort, which translates into a lower cost of ownership and can further result in improved quality and lower risks [REF-2]. Reuse is also an important part of the agile IT enterprise. Composing existing logic to solve larger business problems is more efficient than writing all of the logic from scratch.

Alas, enabling this kind of reuse is not as easy as just incorporating logic into services; it often requires a lot of thinking and design effort to create a service that is truly reusable. But, it can be done. With regards to single-purpose services, reuse is usually not a consideration. These services are specific to parent business process logic and therefore serve just that one purpose. Figure 1 illustrates some common service categories [REF-3] and how they relate to each other and business processes.

(Figure 1: A Service Inventory typically consists of services from multiple categories. Process-specific services can not be reused when implementing support for other business processes. The more process-agnostic a service is the higher it's reusability.)

As just stated, services that cannot be repurposed to automate another business process, as per Non-Agnostic Context, are not considered reusable. However, an important realization here is that logic that solves only one large business problem may still be used by multiple consumers.

Let's explore this notion with a simple analogy. Due to technological advances, the manner in which people perform their jobs today is very different compared to 20 years ago and in the years to come we will probably witness an increase in the rate of technological progress. One kind of change that we have seen is that companies want to enable employees to perform their jobs using different tools in different settings. When we are at our desk we typically expect rich functionality and applications that make the best of our hardware, such as advanced large screens with high resolution and many colors and advanced keyboards with many functions, to name but a few.

On the other hand, we want to be able to do at least some of the same tasks when we are traveling and in that setting we may only have access to, say, a Smartphone. This type of mobile device is much more difficult to work with than a desktop application, and it requires a very different kind of user interface. Processing power, development environments and support for frameworks, among other things, are more limited for Smartphone applications. In spite of these differences, the two applications (desktop and mobile) can still be designed to automate the same task (see Figure 2). As a result, both applications could call the same single-purpose service (which actually does lead to a form of reuse).

(Figure 2: Alice, Bob and Carol work for different departments but are responsible for different activities that make up a business process. Some of the process steps need IT support and some don't. Carol owns a desktop application and a smartphone application. She creates a service to encapsulate the process-related logic that she is responsible for and lets her applications call the service.)

Even though reuse is an important criterion for creating a service it is by no means the only one. In a recent blog post [REF-4] Paul C Brown argues that the main criteria for determining if a capability ought to be put inside a service (apart from reuse) are multiple providers and isolation against change. These are discussed briefly below.

Multiple Providers
The reuse of a service can be thought of as the existence of two or more service consumers. The reverse of this is when you have two or more providers of the service

(Figure 3: Reuse compared to multiple providers.)

Choosing between providers, calling multiple providers, or merging together results from different providers might be non-trivial tasks, and applications can be shielded from this kind of logic by placing it inside a service. Corporate mergers and acquisitions often lead to this kind of scenario, but it can also occur within a company when multiple departments work with overlapping tasks and information. Due to the commonality of this situation, there are design patterns available that describe exactly how to construct such services (e.g. Enterprise Domain Repository [REF-5]).

A problem that must be handled when using multiple providers is that of partial failures. As the number of network links and composed services increases, the probability for failure in one of these links or services increases. To address this, a single-purpose service might securely store messages and make a number of retries to accomplish the delivery of messages to composed services, as per Reliable Messaging. Shielding a consumer from these complex tasks is a good enough reason to create a service, even if it cannot be reused.

Isolation Against Change
Being able to handle change successfully is one of the biggest promises of service-orientation. SOA can help us achieve increased business or organizational agility [REF-6] in several ways, one of which is by developing services and consumers in parallel. This approach requires that we (the service and consumer developers) have first have agreed upon the contract.

Another way is to create new functionality by composing existing services, either our own or services provided by someone else. Yet another important aspect is enabling change by limiting the parts that need development effort to bring about the desired changes. This means making sure that when you change something that the change only affects a limited and preferably isolated part of your software assets. All these issues relate to being able to develop new functionality or change existing functionality with less effort and in a shorter period of time.

To be able to quickly adapt to change can be essential for a business. As Jim Webber so eloquently puts it: "Business people are spaghetti-heads" [REF-7]! Behind this statement lies the profound understanding of the fact that business people need to make new decisions - sometimes even unexpected decisions - in the light of new business demands and opportunities.

Changes in a business process can lead to changes in services, consumers, or both, but there are also justifiable reasons for changing a service even when the business process it encapsulates has not changed.

When implementing a service, there are a variety of realization options ranging from buying or building applications hosted on premise via different hosting options and placing services in the cloud to options that haven't even been conceived yet [REF-8]. These ever-evolving options lead to never-ending opportunities for change that are further influenced by the cost associated with the options, your company's business strategy, and many other factors.

One factor worth calling out is the business strategy, because this strategy itself can be subject to change over time. When a company's strategy changes so will the strategic importance of its services and other IT assets. What this means is that outsourcing may become an option for a particular service today (e.g. to cut costs) but it may be then be necessary to in-source it tomorrow when it becomes more strategically significant (Figure 4)

By encapsulating logic into a service, these kinds of changes will become much easier to handle. A single-purpose service might swap out the current implementation of one of it's composed services with an alternative implementation without changing its contract. To be able to accomplish this you may have to apply Data Format Transformation inside the single-purpose service.

(Figure 4: By creating a service that encapsulates single-purpose functionality it becomes possible to quickly outsource or insource functionality - or choose between any of the options in between - without affecting the consumer)

Although it can be tempting to always plan for this kind of flexibility, it is important to keep in mind that agility may not be the most important factor for all processes or companies. Balancing the need for business flexibility in proportion to the cost of IT flexibility can become the true key to success.

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.

@ThingsExpo Stories
The Internet of Things is not new. Historically, smart businesses have used its basic concept of leveraging data to drive better decision making and have capitalized on those insights to realize additional revenue opportunities. So, what has changed to make the Internet of Things one of the hottest topics in tech? In his session at @ThingsExpo, Chris Gray, Director, Embedded and Internet of Things, discussed the underlying factors that are driving the economics of intelligent systems. Discover how hardware commoditization, the ubiquitous nature of connectivity, and the emergence of Big Data a...
"BSQUARE is in the business of selling software solutions for smart connected devices. It's obvious that IoT has moved from being a technology to being a fundamental part of business, and in the last 18 months people have said let's figure out how to do it and let's put some focus on it, " explained Dave Wagstaff, VP & Chief Architect, at BSQUARE Corporation, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
The major cloud platforms defy a simple, side-by-side analysis. Each of the major IaaS public-cloud platforms offers their own unique strengths and functionality. Options for on-site private cloud are diverse as well, and must be designed and deployed while taking existing legacy architecture and infrastructure into account. Then the reality is that most enterprises are embarking on a hybrid cloud strategy and programs. In this Power Panel at 15th Cloud Expo (http://www.CloudComputingExpo.com), moderated by Ashar Baig, Research Director, Cloud, at Gigaom Research, Nate Gordon, Director of T...
SYS-CON Events announced today that IDenticard will exhibit at 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. IDenticard™ is the security division of Brady Corp (NYSE: BRC), a $1.5 billion manufacturer of identification products. We have small-company values with the strength and stability of a major corporation. IDenticard offers local sales, support and service to our customers across the United States and Canada. Our partner network encompasses some 300 of the world's leading systems integrators and security s...
SYS-CON Events announced today that Windstream, a leading provider of advanced network and cloud communications, 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. Windstream (Nasdaq: WIN), a FORTUNE 500 and S&P 500 company, is a leading provider of advanced network communications, including cloud computing and managed services, to businesses nationwide. The company also offers broadband, phone and digital TV services to consumers primarily in rural areas.

ARMONK, N.Y., Nov. 20, 2014 /PRNewswire/ --  IBM (NYSE: IBM) today announced that it is bringing a greater level of control, security and flexibility to cloud-based application development and delivery with a single-tenant version of Bluemix, IBM's platform-as-a-service. The new platform enables developers to build ap...

The BPM world is going through some evolution or changes where traditional business process management solutions really have nowhere to go in terms of development of the road map. In this demo at 15th Cloud Expo, Kyle Hansen, Director of Professional Services at AgilePoint, shows AgilePoint’s unique approach to dealing with this market circumstance by developing a rapid application composition or development framework.
“In the past year we've seen a lot of stabilization of WebRTC. You can now use it in production with a far greater degree of certainty. A lot of the real developments in the past year have been in things like the data channel, which will enable a whole new type of application," explained Peter Dunkley, Technical Director at Acision, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
DevOps Summit 2015 New York, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that it is now accepting Keynote Proposals. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long development cycles that produce software that is obsolete at launch. DevOps may be disruptive, but it is essential.
"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.
Nigeria has the largest economy in Africa, at more than US$500 billion, and ranks 23rd in the world. A recent re-evaluation of Nigeria's true economic size doubled the previous estimate, and brought it well ahead of South Africa, which is a member (unlike Nigeria) of the G20 club for political as well as economic reasons. Nigeria's economy can be said to be quite diverse from one point of view, but heavily dependent on oil and gas at the same time. Oil and natural gas account for about 15% of Nigera's overall economy, but traditionally represent more than 90% of the country's exports and as...
The Internet of Things is a misnomer. That implies that everything is on the Internet, and that simply should not be - especially for things that are blurring the line between medical devices that stimulate like a pacemaker and quantified self-sensors like a pedometer or pulse tracker. The mesh of things that we manage must be segmented into zones of trust for sensing data, transmitting data, receiving command and control administrative changes, and peer-to-peer mesh messaging. In his session at @ThingsExpo, Ryan Bagnulo, Solution Architect / Software Engineer at SOA Software, focused on desi...
"At our booth we are showing how to provide trust in the Internet of Things. Trust is where everything starts to become secure and trustworthy. Now with the scaling of the Internet of Things it becomes an interesting question – I've heard numbers from 200 billion devices next year up to a trillion in the next 10 to 15 years," explained Johannes Lintzen, Vice President of Sales at Utimaco, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
"For over 25 years we have been working with a lot of enterprise customers and we have seen how companies create applications. And now that we have moved to cloud computing, mobile, social and the Internet of Things, we see that the market needs a new way of creating applications," stated Jesse Shiah, CEO, President and Co-Founder of AgilePoint Inc., in this SYS-CON.tv interview at 15th Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Gridstore™, the leader in hyper-converged infrastructure purpose-built to optimize Microsoft workloads, will exhibit at 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. Gridstore™ is the leader in hyper-converged infrastructure purpose-built for Microsoft workloads and designed to accelerate applications in virtualized environments. Gridstore’s hyper-converged infrastructure is the industry’s first all flash version of HyperConverged Appliances that include both compute and storag...
Today’s enterprise is being driven by disruptive competitive and human capital requirements to provide enterprise application access through not only desktops, but also mobile devices. To retrofit existing programs across all these devices using traditional programming methods is very costly and time consuming – often prohibitively so. In his session at @ThingsExpo, Jesse Shiah, CEO, President, and Co-Founder of AgilePoint Inc., discussed how you can create applications that run on all mobile devices as well as laptops and desktops using a visual drag-and-drop application – and eForms-buildi...
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core of our infrastructures. At the same time, we have old approaches made new again like micro-services...
Code Halos - aka "digital fingerprints" - are the key organizing principle to understand a) how dumb things become smart and b) how to monetize this dynamic. In his session at @ThingsExpo, Robert Brown, AVP, Center for the Future of Work at Cognizant Technology Solutions, outlined research, analysis and recommendations from his recently published book on this phenomena on the way leading edge organizations like GE and Disney are unlocking the Internet of Things opportunity and what steps your organization should be taking to position itself for the next platform of digital competition.
The 3rd International Internet of @ThingsExpo, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that its Call for Papers is now open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
As the Internet of Things unfolds, mobile and wearable devices are blurring the line between physical and digital, integrating ever more closely with our interests, our routines, our daily lives. Contextual computing and smart, sensor-equipped spaces bring the potential to walk through a world that recognizes us and responds accordingly. We become continuous transmitters and receivers of data. In his session at @ThingsExpo, Andrew Bolwell, Director of Innovation for HP's Printing and Personal Systems Group, discussed how key attributes of mobile technology – touch input, sensors, social, and ...