Service Oriented Architecture is mostly popular because it promises interoperability between heterogeneous applications and technologies with least hassle in application integration. A service’s loose coupling to host applications gives it the ability to share data across enterprises more easily. Using SOA’s increase reusability, overall costs could be minimized with increased response times to ITs change requests. This results in rapit evolvement of IT systems, for both old and new.

However, as the organization matures, they tend to face the following challenges with SOA:

• Number of new services increases
• Number of dependencies among services increases
• Number of service users (both internal and external to the organization) increases
• Users develop interest in different versions of the same service
• Users sign up for different service level agreements, e.g. John’s request will go through high performance servers, while Jennifer’s requests go through regular servers.

If not properly handled, and organization’s SOA could transform into a complex unmanageable mesh. To avoid this situation, an organization should (but not limited to) perform the following  throughout the entire lifecycle of services:

• Properly manage services creation, adhering to rules laid down by an organization
• Increase reuse of services, by “socializing” existing services
• Properly analyze dependencies of a given service, before changing it
• Provide service versioning and allow users to consume different versions of a given service
• Properly validate services for standard compliance
• Properly test services to assure quality of services
• Document both technical and business aspects of services to help consumers and providers
• Properly define who accesses what services
• Measure service behavior at runtime. (e.g. How many times this service is called, by how many consumers, etc..)

In other words, SOA should properly “steer” its enterprise IT system. This process is called “SOA Governance”. Governance is derived from the Latin term for steering.

People tend to define Service Oriented Architecture Governance differently, such as:

SOA Governance is processes that an enterprise puts in place to ensure that things are done, in accordance with best practices, architectural principles, government regulations, laws, and other determining factors. SOA governance refers to the processes used to govern adoption and implementation of SOA.

- Anne Thomas Manes, Burton Group.

Governance establishes the alignment in SOA. This involves understanding organizational business value drivers and business processes, aligning them to IT policies and establishing a process model to implement the alignment.

- Nikhil Kumar, CXO Magazine.

SOA Governance is about having discipline and making sure that the very important decisions go through to appropriate people and that these people have the appropriate input to make those decisions. That is half of the SOA governance problem. The second half is whenever these decisions are made, SOA governance needs to make sure that those decisions are actually followed. It’s not only about setting a speed limit, it is about enforcing it too and eventually giving people tickets or sending them to jail. That is what SOA governance really is about.

- Paolo Malinverno, Gartner.

In simple terms, SOA governance is a set of processes, responsibilities and tools that reinforces good behavior and help avoid bad behaviors. It is all about control. If you design a service for a specific purpose and for a set of consumers, you will want to have assurance that it will only be used for that purpose and by that set of consumers. You also want the service to be available, performing as it was intended for, and secured. Transactions must have integrity, at least to the degree that you originally specified. Most Importantly, you need to make sure defined processes and responsibilities are followed properly. For this you need to adapt proper measurement techniques (to measure effectiveness on the actions taken) in your SOA.

In the modern day, information technology (IT) systems of the enterprise are continuously challenged with demands to serve ever changing requirements. In order to get more out of existing investments, rather than developing new applications to serve such demands, IT companies are moving towards the service-oriented paradigm.

What is a service?

In the service oriented paradigm, a service is a well-defined and self-contained function, one that would not not depend on the context or state of other services.

SOA?

Developing services and deploying them using a service-oriented architecture (SOA) is the best way to utilize existing IT systems to meet new challenges. SOA represents a new generation of distributed computing architecture.

Definition of SOA!

According to the OASIS SOA Reference Model definition[1], “SOA is a paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains. It provides a uniform means to offer, discover, interact with and use capabilities to produce desired effects consistent with measurable preconditions and expectations“.

In simple terms, Service-oriented Architecture is a collection of services. Services in a SOA can communicate with each other. This communication could take the shape of either simple data processing, or, it could even involve two or more services coordinating some activity. The combination of services, both internal and external to an organization, makes up a service-oriented architecture.

[1] http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=soa-rm