Welcome!

Microservices Expo Authors: Liz McMillan, Elizabeth White, Jason Bloomberg, Anders Wallgren, Derek Weeks

Related Topics: Microservices Expo

Microservices Expo: Article

SOA Book Excerpt: The First-Class Constructs of SOA - Part 3

Services, service components, and flows

In SOA, the main emphasis is on the identification of the right services followed by their specification and realization. Although some might argue that object-oriented analysis and design (OOAD) techniques can be used as a good starting point for services, its main emphasis is on microlevel abstractions. Services, on the other hand, are business-aligned entities and therefore are at a much higher level of abstraction than are objects and components.

In Part 1 of this book excerpt, we discussed the different layers of an SOA Reference Architecture, and in Part 2 we discussed Service Oriented Modeling and Architecture, and Part 3, we move on to the second phase in the method: specification of services.

Specification
The specification phase helps design the details of the three first-class constructs of SOA: services, service components, and flows. It uses a combination of three high-level activities to determine which services to expose, provides a detailed specification for the exposed services, and specifies the flows (processes) and service components. The three activities are called service specification, subsystem analysis, and component specification. From a service model work product standpoint, this phase provides the most content: The service exposure, service dependencies, service composition, service NFRs, service messages, and state management are all addressed in this phase. The rest of this section focuses on the three activities.

Service Specification
Service specification defines the dependencies, composition, exposure decisions, messages, QoS constraints, and decisions regarding the management of state within a service.

The first task concerns service exposure. The service portfolio had an exhaustive list of services obtained through the three techniques that we used for service identification. It is easy to comprehend that this list may contain too many candidate services; not all of them are at the right level of granularity to be exposed as services. Some of the service candidates may be too coarse-grained and might actually be more like business processes or subprocesses rather than individual services (for example, some of the process elements derived from the first level of process decomposition), whereas some others may be too fine-grained IT functions (for example, the process elements in the lowest level of process decomposition and some of the existing system functionality). Deciding to expose the entire list of candidate services is a perfect recipe for following a perfect antipattern in SOA - the service proliferation syndrome (a phenomenon we want to avoid). Some economic and practical considerations limit the exposure of all candidate services. A cost is associated with every service chosen for exposure. The funding of the entire service life cycle, the governance factor around service life-cycle management, and the added underlying infrastructure requirements to support security, scalability, performance, and other nonfunctional requirements make it impractical to follow the rules of economies of scale when it comes to exposing all candidate services.

Based on these premises, we recommend a service litmus test. The test consists of specific criteria applied to the candidate services. Only those services that meet the criteria are chosen for service exposure. The method provides an initial set of test criteria in the following form:

  1. Business alignment: A service must be business aligned. If a service is not, in some shape or form, traceable back to a business goal, it may not be an ideal candidate to be chosen for exposure.
  2. Composability: Tests the ability of a service to be used in a context entirely different from the one from which the service was originally identified. A service should be able to participate in multiple business processes without compromising the NFR compliance requirements for the process.
  3. Feasibility of implementation: Tests the technical feasibility of implementing the service in a cost- and time-effective manner. Practical considerations limit overly complex services to be commissioned for implementation.
  4. Redundancy elimination: Tests whether the service can be used within all processes and applications where its function is required.

More Stories By Tilak Mitra

Tilak Mitra is a Certified Senior IT Architect at IBM. He specializes in mid- to large-range enterprise and application architectures based on J2EE, MQ, and other EAI technologies. You can reach him at [email protected]

More Stories By Norbert Bieberstein

Norbert Bieberstein, solution architect for IBM's Enterprise Integration team, has extensive first-hand experience with customers migrating to SOA-based On-Demand solutions.

More Stories By Keith Jones

Keith Jones, PhD, IT architect at IBM Enterprise Integration Solutions, focuses on helping customers define and implement service-oriented architectures.

More Stories By Robert Laird

Robert Laird is an IT architect in IBM's SOA Advanced Technologies group.

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
This is not a small hotel event. It is also not a big vendor party where politicians and entertainers are more important than real content. This is Cloud Expo, the world's longest-running conference and exhibition focused on Cloud Computing and all that it entails. If you want serious presentations and valuable insight about Cloud Computing for three straight days, then register now for Cloud Expo.
SYS-CON Events announced today that Stratoscale, the software company developing the next generation data center operating system, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Stratoscale is revolutionizing the data center with a zero-to-cloud-in-minutes solution. With Stratoscale’s hardware-agnostic, Software Defined Data Center (SDDC) solution to store everything, run anything and scale everywhere...
SYS-CON Events announced today that Men & Mice, the leading global provider of DNS, DHCP and IP address management overlay solutions, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. The Men & Mice Suite overlay solution is already known for its powerful application in heterogeneous operating environments, enabling enterprises to scale without fuss. Building on a solid range of diverse platform support,...
You deployed your app with the Bluemix PaaS and it's gaining some serious traction, so it's time to make some tweaks. Did you design your application in a way that it can scale in the cloud? Were you even thinking about the cloud when you built the app? If not, chances are your app is going to break. Check out this webcast to learn various techniques for designing applications that will scale successfully in Bluemix, for the confidence you need to take your apps to the next level and beyond.
Digital means customer preferences and behavior are driving enterprise technology decisions to be sure, but let’s not forget our employees. After all, when we say customer, we mean customer writ large, including partners, supply chain participants, and yes, those salaried denizens whose daily labor forms the cornerstone of the enterprise. While your customers bask in the warm rays of your digital efforts, are your employees toiling away in the dark recesses of your enterprise, pecking data into...
SYS-CON Events announced today that DatacenterDynamics has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY. DatacenterDynamics is a brand of DCD Group, a global B2B media and publishing company that develops products to help senior professionals in the world's most ICT dependent organizations make risk-based infrastructure and capacity decisions.
With DevOps becoming more well-known and established practice in nearly every industry that delivers software, it is important to continually reassess its efficacy. This week’s top 10 includes a discussion on how the quick uptake of DevOps adoption in the enterprise has posed some serious challenges. Additionally, organizations who have taken the DevOps plunge must find ways to find, hire and keep their DevOps talent in order to keep the machine running smoothly.
Call it DevOps or not, if you are concerned about releasing more code faster and at a higher quality, the resulting software delivery chain and process will look and smell like DevOps. But for existing development teams, no matter what the velocity objective is, getting from here to there is not something that can be done without a plan. Moving your release cadence from months to weeks is not just about learning Agile practices and getting some automation tools. It involves people, tooling and ...
Between the mockups and specs produced by analysts, and resulting applications built by developers, there exists a gulf where projects fail, costs spiral, and applications disappoint. Methodologies like Agile attempt to address this with intensified communication, with partial success but many limitations. In his session at 18th Cloud Expo, Charles Kendrick, CTO & Chief Architect at Isomorphic Software, will present a revolutionary model enabled by new technologies. Learn how business and devel...
The notion of customer journeys, of course, are central to the digital marketer’s playbook. Clearly, enterprises should focus their digital efforts on such journeys, as they represent customer interactions over time. But making customer journeys the centerpiece of the enterprise architecture, however, leaves more questions than answers. The challenge arises when EAs consider the context of the customer journey in the overall architecture as well as the architectural elements that make up each...
APIs have taken the world by storm in recent years. The use of APIs has gone beyond just traditional "software" companies, to companies and organizations across industries using APIs to share information and power their applications. For some organizations, APIs are the biggest revenue drivers. For example, Salesforce generates nearly 50% of annual revenue through APIs. In other cases, APIs can increase a business's footprint and initiate collaboration. Netflix, for example, reported over 5 bi...
As the software delivery industry continues to evolve and mature, the challenge of managing the growing list of the tools and processes becomes more daunting every day. Today, Application Lifecycle Management (ALM) platforms are proving most valuable by providing the governance, management and coordination for every stage of development, deployment and release. Recently, I spoke with Madison Moore at SD Times about the changing market and where ALM is headed.
If there is anything we have learned by now, is that every business paves their own unique path for releasing software- every pipeline, implementation and practices are a bit different, and DevOps comes in all shapes and sizes. Software delivery practices are often comprised of set of several complementing (or even competing) methodologies – such as leveraging Agile, DevOps and even a mix of ITIL, to create the combination that’s most suitable for your organization and that maximize your busines...
These days I mostly make my living as a consultant. Consultants in general are probably not the best loved group in the world. It is common to think of consultants wafting-in to your organization, telling you things that you already know and advising you to “change your culture”, whatever that means. Subsequently they depart, no-doubt with a fat fee, and leave you as you were before with the same problems and no progress made.
Struggling to keep up with increasing application demand? Learn how Platform as a Service (PaaS) can streamline application development processes and make resource management easy.
In the rush to compete in the digital age, a successful digital transformation is essential, but many organizations are setting themselves up for failure. There’s a common misconception that the process is just about technology, but it’s not. It’s about your business. It shouldn’t be treated as an isolated IT project; it should be driven by business needs with the committed involvement of a range of stakeholders.
New Relic, Inc. has announced a set of new features across the New Relic Software Analytics Cloud that offer IT operations teams increased visibility, and the ability to diagnose and resolve performance problems quickly. The new features further IT operations teams’ ability to leverage data and analytics, as well as drive collaboration and a common, shared understanding between teams. Software teams are under pressure to resolve performance issues quickly and improve availability, as the comple...
The goal of any tech business worth its salt is to provide the best product or service to its clients in the most efficient and cost-effective way possible. This is just as true in the development of software products as it is in other product design services. Microservices, an app architecture style that leans mostly on independent, self-contained programs, are quickly becoming the new norm, so to speak. With this change comes a declining reliance on older SOAs like COBRA, a push toward more s...
Join IBM June 8 at 18th Cloud Expo at the Javits Center in New York City, NY, and learn how to innovate like a startup and scale for the enterprise. You need to deliver quality applications faster and cheaper, attract and retain customers with an engaging experience across devices, and seamlessly integrate your enterprise systems. And you can't take 12 months to do it.
The proper isolation of resources is essential for multi-tenant environments. The traditional approach to isolate resources is, however, rather heavyweight. In his session at 18th Cloud Expo, Igor Drobiazko, co-founder of elastic.io, will draw upon their own experience with operating a Docker container-based infrastructure on a large scale and present a lightweight solution for resource isolation using microservices. He will also discuss the implementation of microservices in data and applicat...