Up until now, there has been such a rush to roll out initial SOA services and supporting infrastructure, that little attention has been given to what good service design truly entails.  This is a natural evolution that must occur with any technology or methodology.  Throughout this summer, I plan on releasing several posts regarding proper service design.

Initially, I would like to focus on the subject of ‘composability’.  Composable services have several important qualities:

• composable services stictly adhere to their service interface, Service Level Agreements(SLAs), and supporting metadata
• service operations always leave enterprise data in a valid business state
• service operations can be called indepently, in parallel, or as a part of a larger service orchestration
• service operations can be called within or without a transaction context

When you boil it down to the essentials, composable services clearly define what they do and they do exactly what they have defined.  Consumers of composable services are then at liberty to determine how they want to use that service’s operations, rather than the service having certain built-in assumptions regarding how the service will be used or what the larger business context ought to be.

To learn more about the merits and details of composable services, I recommend the following resources:

• “Composable Services” (MSDN Library)
• “Service Composability” (SOAprinciples.com)
• “A Composable Service is a Good Service” (Presentation at SOAWorld 2008 next week)

There’s another, less tangible benefit of composable services — they are lower stress.  The frustration and stress associated with consuming a service that later fails due to some unknown buisiness logic violation is supremely frustrating.  Consuming services that are not composable is stressful, because they cannot be depended upon to work in whatever context you choose.  Likewise, publishing non-composable services for consumption is stressful because the service provider is constantly in fear that someone will ‘misuse’ a service.  This is no way to run an enterprise or encourage the adoption of service orientation. 

I’ll explore all of these topics next week in my presentation at SOAWorld on composable services.  I’ll post the completed presentation as well as perspectives from the audience next week.  Have a great weekend and I’ll see you in New York!

Primitive man and woman were forced to adapt to their environment to survive. Animal hides for clothes, crude weapons and tools made out of stone or bone, and roots or berries for food (perhaps sabertooth steak or terradactyl ribs if company is coming over). Eventually, some nearby tribe discovers fire, but reports of fire-related injuries and property destruction lead our cave dwellers to avoid this new magic. These primitive humans are doing fine with their current capabilities and they are able to meet their basic needs without dabbling with such things. Over time the nearby tribe’s use of fire expands and one very enterprising woman invents pit fired pottery. The more primitive people have heard and seen the potential of this new breakthrough and are interested in using it. Alas, the obstacles to adopting this innovation are not trivial. They must learn how to create fire, handle fire cautiously, locate and stockpile flint and tender, develop fireproof tools, create fire pits, learn to craft with clay and finally develop a process to fire the clay pots successfully. Lack of education, skills, infrastructure, resources, and processes hinder their ability to progress. Perhaps the greatest barrier for these primitive people is fear of the unknown and risk of failure. Thousands of years later, we are faced with the same technology adoption challenges — education, skills, infrastructure, resources, processes, and fear.

Modernizing legacy information systems is not unlike the modernization efforts that have occurred for thousands of years. In fact, legacy or heritage systems are often referred to as ‘dinosaurs’. Correspondingly, the same types of obstacles must be overcome:

• Education — There is a mindset shift that must take place to understand the service oriented way of thinking. At first glance, services are just fancy objects. The reality is that service orientation requires a much broader, end-to-end view of the enterprise, complete with process-centric alignment, layered architecture, contracted interfaces, standards-based connectivity, and full life cycle governance. I have blogged about the alignment of service orientation and the unique qualities of SOA before. Also, David Ing has some interesting thoughts on service orientation.
• Skills — A well documented skills gap exists around service orientation. Joe McKendrick sites it as one of the two things killing SOA in 2008 and the guys over at ZapThink have been alerting the industry to the dangerous SOA skills gap for quite some time. Why is this? Service orientation skills cannot be acquired by attending a conference or reading a book (although I do have a book that I HIGHLY recommend). Academic learning as well as hands-on mentoring is required. Moreover, there are nuances to effective service orientation, service design, process alignment, and enterprise governance that require time and experience to develop. There are new technologies, design patterns, techniques, and methodologies that must be introduced and ultimately absorbed. This will require instructor-led training, research, hands-on mentoring, and practical experience to develop proficiency in these areas.
• Infrastructure — Contrary to popular belief, a service oriented infrastructure cannot be achieved by purchasing an Enterprise Service Bus (ESB) from a vendor and adding water. There are, in fact, a variety of infrastructure elements (service registry/repository, governance suite, business process engine, policy manager, policy enforcer, and etc.). There is a great little SOA infrastructure white paper that a consortium of vendors put together a while back. Additionally, be sure to avoid the trap of assuming that you need to have your SOA infrastructure fully mature on day one. Eric Newcomer has a great post from a couple years back regarding an incremental adoption of SOA infrastructure.
• Resources – There are several ways to slice the resource issue. For effective adoption of SOA, you will need a pool of human resources (with appropriate education and skills), technical resources (infrastructure, knowledge management and collaboration tools, as well as design and development tools), and you will need expert resources (developed in-house, or brought in from an outside source initially).
• Processes — All the education, skills, infrastructure, and resources in the world won’t amount to a hill of Java beans without effective processes for governing the adoption of service orientation. You will need processes for service selection, service design, quality assurance and testing, policy enforcement, and runtime service management. Effective governance can make or break your adoption of SOA. I have blogged on the importance of service oriented governance numerous times.
• Fear – People fear change. Service orientation appears threatening to many people at first due to the changes required in adopting it. New patterns of thinking are required around how to solve customer problems. Skills must be adapted, other skills developed from scratch. New infrastructure and resource pools must be created and processes must be adapted and new processes created. These changes can be intimidating. A considerable degree of people change management must be accepted as a part of a successful transition toward service orientation.

Service orientation adoption is challenging in its own right. It becomes increasingly challenging when you factor in the dinosaurs that must be modernized as a part of the adoption process. Immediately, questions begin to arise:

• What systems and/or business processes should be modernized?
• Should we migrate, expose, or leverage our existing legacy assets?
• Should adoption occur within a particular line of business or across the whole of the enterprise?
• How will modernization impact existing teams and project roles?

These questions and many more must be explored as part of the adoption of service orientation. I explored several of these topics in a recent public webinar - Enterprise Modernization and SOA Concepts (pdf).

Another resource you might consider is a new course that Web Age has been offering since April of this year. It is a two-day workshop that explores the modernization of legacy applications, SOA concepts, modernization challenges and risks, and various strategies for modernizing legacy systems. It is aimed at team leads, architects, managers, and legacy application support personnel. For more details, check out the course details - WA1657 Application Modernization and SOA Concepts.

Adopting service orientation and “moving out of the Stone Age” is not a simple task. It requires intentional allocation of time, energy, and resources. It cannot and should not be approached in an ad-hoc fashion. Technology adoption has always been challenging, just like when ancient man and woman adopted fire. When it comes to service orientation, be sure that you work through the necessary steps of adopting education, skills, infrastructure, resources, processes, and addressing the fear factor. Otherwise, you just might get burned.