Service-Oriented Process: Thinking About Processes Before Services
When people are first exposed to a new technology, their first urge is to apply yesterday’s approaches, theories, and concepts to that new technology. It is only natural, of course, to think of new technologies the way that one traditionally thought of the old technology that it might be replacing, because there is simply no experience yet with how the new technology can be best applied. Every technology goes through this “horseless carriage” phase of technology adoption, so named because when the automobile first came out, people inappropriately applied their knowledge of how to build and use horse carriages to automobiles. However, at some point, some smart individuals or groups realize that the new technology doesn’t need to follow the same path as the old one, and the true benefits of the technology can finally be realized. This is when the market for that product really takes off.
Today, we’re in the horseless carriage phase for Web Services and (Service-Oriented Architectures (SOAs). The traditional mindset that needs changing is the view that Web Services are an extension of the component object model. To many developers, Web Services are simply “another interface to a compiled object.” As a result, they apply their traditional component object design methods, deployment technologies, scalability and reliability approaches, and even terminology. The result: point-to-point implementations of Web Services that are every bit as brittle, tightly coupled, synchronous, and fine-grained as their object-oriented predecessors. In essence, these developers are taking a “bottom-up” view of Web Services where the service implementation is the center of the world. As these developers are quickly realizing, thinking of Web Services as connected to a particular object model (.NET or J2EE, for example) or implementation approach (application servers vs. messaging middleware, for example) makes meeting the basic principles of SOAs a challenge.
Instead of thinking of Web Services as a collection of interfaces to software functionality that must somehow be made to connect to other such interfaces, enterprises should approach Web Services as enabling a fundamentally process-driven architecture that leverages distributed processes in addition to distributed services. We all understand distributed services-it’s distributed computing based on the notion that service interfaces should be standardized and service descriptors and registries should be used to allow for runtime binding. However, distributed processes are all about the creation of business processes that in turn depend on other business processes that may be defined anywhere in the organization. Those business processes then at some point depend on atomic services to fulfill the activities required by their process flow.
Approaching SOAs and Web Services from this “Service-Oriented Process” perspective simplifies and clarifies many of the troublesome issues relating to distributed computing and Web Services. Integration goes from being a troublesome chore that must be accomplished through implementing increasing layers of complicated and expensive technologies to a side effect of process execution. In fact, it’s difficult to create a Service-Oriented Process that does not provide the fundamental benefits of application and business integration. The mere act of orchestrating and choreographing a Service-oriented business process accomplishes the task of most integration goals.
What is Service-Oriented Process?
While SOAs provide a homogeneous and loosely coupled infrastructure for service description and invocation, they don’t offer a specific approach to connecting the IT capabilities to the business requirements as we have discussed in earlier ZapFlashes. Since the main rationale for implementing SOAs is to obtain quantifiable efficiencies and ROI, companies need to somehow connect the business requirements established by management with the services and capabilities deployed with Web Services. For this to happen, SOAs must be able to support reliable, durable and at times complex business processes. The application of business process to SOAs is known as Service-Oriented Process.
Individual, atomic Web Services are not particularly interesting. A business comprised of hundreds of discrete Web Services isn’t particularly efficient. What is more interesting is the composition of multiple Web Services into a coherent business process that meets business requirements. In order for this composition to occur, we need a way of composing atomic, fine-grained Web Services into coarse-grained business services.
Of course, in order to perform this composition, we need to apply business process techniques to Web Services.
Business process methodologies are not particularly new. However, what is unique about Web Services-based SOAs, is that in an SOA, a process is a service. Individual services can be composed into a process flow that itself can be described as a service using the same Web Services standards. The ability for services to be consumed by processes that can then be described as services is a very potent notion that shouldn’t be overlooked. The services that are consumed by a process might be services local to an enterprise or available at a remote location. In this regard, a Service-Oriented Process exhibits the location independence as well as implementation independence features of loose coupling. A business process description (or flow model) can be published as a Web Service, described via WSDL and interacted with using SOAP. As a result, it becomes impossible to distinguish whether an invoked service is an atomic service or a service composed with business process. Users simply invoke the Web Service, which has been either specified statically, or determined dynamically through the use of a service registry.
Integration as a Side-Effect of Distributed Processes
In effect, many forward-looking integration efforts have tried to achieve some of the goals that business process approaches promise. Whenever multiple applications or organizations are expected to behave as if they were part of a cohesive and well-integrated architecture, many dimensions of business process come into play. A goal of many large organizations is that the various applications, repositories, and even roles or organizations appear to be well aggregated and integrated even though they are discrete entities that may be distributed across many departments and other enterprises. The different groups involved in the ultimate objective need to be part of the same overall business objective, and the primary way to make sure that all the various components and resources operate in synch is by coordinating them through formalized business process. The problems of integration can thus be reconceived as a part of the general problem of representing an executing business process.
It’s quite possible that a few years from now, companies won’t be spending so much of their time and money on integration middleware and approaches anymore. Instead, it will be the responsibility of every application that participates in a process to provide the necessary layers of integration. The enterprise architecture will provide integration capabilities, because it will be process driven. Enterprises will then be able to focus on more important aspects of their business: modeling their business requirements and processes, and building the IT systems that meet those goals.