3: SOA Value Proposition
The author describes a number of "value propositions" that describe the potential benefits to a company for adopting SOA.
SOA can reduce integration expenses by providing a middleware layer of common functions and data objects, which makes integration more straightforward (each system need only communicate with the service layer, in a hub-and-spoke fashion, not directly with every other system, which would create a complex web).
SOA reduces system maintenance and development costs by providing a smaller number of shared services in place of having separate and redundant functionality in each system.
SOA creates assets that can be reused, which the author refers to as the "holy grail": of information technology. The enterprise can create a "library" of software that can be used by various project teams, eliminating the need for separate project teams to have to develop and maintain original code as well as the cost of training staff on redundant capabilities.
SOA increases the agility of a company, enabling it to produce new applications and systems by drawing on the functionality if existing services rather than having to develop them afresh for each project, which enables new solutions to be developed and existing systems to be modified rapidly and the work of developing small, lightweight services can be divided among many developers more readily than a single monolithic information system.
SOA also reduces operational risk by enabling development teams to touch fewer components in order to develop new capabilities and building control and error-trapping into services, preventing any malfunction fro having a widespread impact on all systems. (The crash or malfunction of a service that performs a small function is less damaging than one of a large system that performs many functions).
SOA reduces compliance risk by enabling developers to quickly isolate and adjust specific services that may be impacted by a change in legislation in a timely manner, universally (if services are reused), and with greater discrimination (targeting specific functions instead of entire systems).
SOA VALUE, BEYOND THE CORE
The author also lists some of the high-level qualitative advantages of adopting SOA:
SOA provides for better alignment between the IT department and the rest of the business, enabling them to collaborate on the design of resources to support tasks rather than being disconnected, with a requirements document being the sole tangency.
In the same way, SOA increases the visibility of the IT department within the organization, leading to a better understanding of their role and more regular communication, which improves the position of the IT department and helps to educate business mangers about the potential of technology.
SOA reduces the amount of time it takes for an idea to be acted upon and implemented within the organization.
SOA helps to modernize the business operations, by ensuring that business mangers are aware of recent changes in technology and making the cost of upgrades feasible (cheaper and faster to upgrade a service than a monolithic system).
SURGICAL ADOPTION OF SOA
A brief note: replacing legacy systems with SOA components need not be an all-or-nothing proposition. While transitioning completely away from older systems is the ultimate goal, it can be done on a project-by-project basis.