Book Excerpt: Enabling Agile Business with SOA
Chapter 3: SOA Value Proposition
By: Kyle Gabhart
Dec. 23, 2008 06:00 AM
Each system in Figure 1 is directly connected to the systems with which it must interact during the course of operation. In some cases, external partners are even coming in through the firewall to directly access enterprise systems. In this particular example, the enterprise resource planning (ERP) system is a key component of the enterprise (typical for manufacturing, engineering, and product-centric businesses). It is a mission-critical system that the entire supply chain hinges upon. When significant changes need to be made to such a system (either upgrading to a new system or even just moving to the next major release), the impact of such a change can ripple throughout the enterprise. Figure 2 illustrates this ripple effect, impacting other systems and even the external systems of external business partners.
Figure 2: Changes to the tightly integrated environment produce a catastrophic ripple effect
So how does SOA help with this? If you remember the SOA stack introduced in Chapter 1, these layers of abstraction insulate the enterprise so that changes do not ripple past interface boundaries. By containing the impact of these changes, service orientation keeps development and maintenance costs low and also reduces risk (another value proposition that we will discuss in the “Reducing Risk” section).
Increasing Asset Reuse
Question: What do the following things have in common?
Answer: None of them have ever been designed to be reused.
While some might take exception to this, the reality is that reuse has become something of a holy grail in the information technology (IT) realm. Project managers, business divisions, and even entire enterprises have been chasing it for decades and many have concluded that it is merely a well-fabricated myth. It should come as no surprise, then, that proponents of service orientation are heralding the value of reuse as a major reason to adopt SOA. Those who are relatively new to the industry are quite excited about the prospects of service-oriented reuse. Those of us who have been around for a while, however, recognize that each new technology wave takes up the reuse mantra and espouses the virtues of its particular approach. Service orientation falls prey to this as well. In an attempt to determine the validity of SOA’s reuse claim, we will start by examining software reuse in general; then we will highlight the shortcomings of previous strategies, and finally examine the potential for SOA to actually deliver on the promise of reuse.
Copy-and-Paste as Reuse
Figure 3: Traditional reuse is more like glorified copy-and-paste
Service Oriented Reuse
Reusing services is a bit different. A service is created and hosted in one place. If another application or system needs to utilize that service, it simply needs to send an appropriately formatted message to the service address (see Figure 4). Additional copies of the service do not get distributed all over the enterprise. Certainly there still will be a need for additional versions of the service to be created, but they are centrally managed and additional uses of the service can be easily supported without losing control.
Figure 4: Service oriented reuse enables capabilities to be reused in different contexts
Customers and the market at large seem to value speed and responsiveness over safe, methodical business practices. Responding to opportunities in a matter of weeks or months is no longer acceptable. Previously, this was the advantage of working with smaller firms, but now even large organizations are expected to be nimble and able to adapt quickly to new opportunities. This is what is meant by the term agility. Agility is a measure of how quickly an organization can modify existing capabilities, create new products and services, or modify business processes. Service orientation raises the visibility of underlying business rules and enables rapid turnaround of new and modified business capabilities.
By breaking monolithic information systems into a collection of services, business capabilities can be more quickly and easily modified. For example, a company might have developed some customer account profile services and order-tracking services for use internally by employees. Later, there is a desire to create a customer account management portal to serve customers better and reduce the number of calls made to the customer support center. As illustrated in Figure 5, the existing services could be used to provide access to customer profile and order history and a few additional services created to add visibility into the technical support database.
All of these services could be consumed by a Web portal that is then made available to customers. In the absence of an SOA, all of these capabilities would need to be built from scratch or, at a minimum, copied from other applications and then integrated into the new application. Either way, a service-oriented solution is faster and cheaper to develop. That is how SOA enables agile business.
Figure 5: Service Orientation enables business agility
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