Service-Oriented Architecture

The phrase "SOA governance" is more likely to generate a sense of apprehension among IT professionals than any warm feelings. After all, most companies are still in the early stages of SOA adoption and so the practice of governance - and likely the concept itself - will be new territory. Yet, if companies are to realize any meaningful and lasting impact from SOA, then governance is a fact of life with which organizations are going to have to become comfortable. Governance - more than any other factor over the long term - will make the difference between SOA success and failure, and proficiency in governing the SOA environment will distinguish IT leaders from laggards.

SOA Governance Defined
While the term may be novel, the act of governance and the underlying rationale will be very familiar to IT. In most organizations, virtually every IT resource and process will have some level of governance associated with it in the form of policies, rules, and controls that define how a particular asset is managed and utilized, or parameters around how a certain IT function is performed. For example, IT management will have established policies for how projects are initiated, funded, prioritized, and staffed. An enterprise application package such as SAP or Siebel will have rules and operational procedures concerning issues such as how change requests are processed and approved, which employees are allowed access to the system and their level of access, and how new versions of the software are rolled out. Collectively, the act of establishing and enacting these rules falls under the broad umbrella of IT governance, in order to institutionalize discipline and maturity in IT processes so as to gain greater control and economies.

SOA governance, then, is the subset of IT governance related to establishing policies, controls, and enforcement mechanisms - within the context of the activities and constructs associated with SOA - similar to those that exist for managing and controlling other aspects of IT. Initially, the concept of SOA governance was applied narrowly to the development and use of Web services, for example, validating the conformance of a Web service with specific standards or managing Web services in the SOA runtime environment. Today, however, it is generally understood that SOA governance has a broader meaning that spans SOA architecture as well the governance of services across the entire implementation life-cycle.

Before exploring the scope of SOA governance in further detail, it is worth considering why governance is so fundamental to SOA's success.

The Case for SOA Governance
SOA provides organizations with a powerful opportunity to transform the way in which they deploy information technology. This includes benefits for both the IT organization and the line of business. For IT, these benefits include:

• Increased standardization of systems and operational practices
• An improved ability to consolidate existing computing assets to eliminate redundant functionality, while preserving needed features and services
• The development of new systems offering higher levels of visibility, control, and compliance
• The ability to evolve the systems infrastructure incrementally

For the business, SOA holds the promise of increasing the flexibility of IT resources, improving the visibility and adaptability of business processes, and increasing the organization's agility and responsiveness to market conditions.

By definition, however, enterprise-level SOA means a dramatic increase in the number of moving parts in the environment. The trade-off is that this increase in the number of moving parts is accompanied by a corresponding increase in complexity.

Each service is an asset that has to be properly designed to be useful within a larger portfolio of business services; each must be versioned, secured, managed, and monitored to ensure that it performs with the expected quality of service. IT is accustomed to dealing with these issues on an aggregate level - at the scope of an application package, for instance - but SOA creates a challenge that is an order of magnitude greater by requiring these issues to be addressed at the level of individual services. Further compounding the challenge is the fact that services use and interact with other services, increasing the complexity of change management, testing, and deployment. How do you recreate a network of interdependent services in an isolated environment to perform regression testing, for example?

Thus, success with SOA is highly correlated with an organization's ability to manage complexity and to develop the necessary maturity and infrastructure - in the form of governance control and enforcement mechanisms - to maintain order over the SOA environment. Without effective SOA governance, organizations will experience some predictable challenges, including:

• A fragile and brittle SOA implementation
• Services that cannot easily be reused because they are unknown to developers or because they were not designed with reuse in mind
• Lack of confidence in services as enterprise assets which results in a "build it myself" mentality (further compounding the lack of reuse with redundancy and unnecessary duplication of functionality)
• Security breaches that cannot easily be traced
• Unpredictable performance

Failure to overcome these challenges will cause a drag on an organization's continued deployment of SOA and, in all likelihood, result in SOA being discarded as a failure. Fortunately, the majority of organizations exploring SOA recognizes the need to address these issues, and companies who are serious about SOA are generally serious about governance, too.

So, having established the importance of governance in making SOA successful, on what fronts is SOA governance required?

Architecture Governance
The first requirement of SOA governance is "architecture governance." Architecture governance is necessary to ensure that SOA as architecture evolves by design and not by accident. To the extent that it mirrors governance requirements in other areas of IT architecture, SOA architecture governance practices can be adapted from existing Enterprise Architecture processes. These include:

• Establishing corporate technology standards
• Defining the high-level SOA architecture and topology , as well as the infrastructure capabilities that the SOA should incorporate
• Determining the SOA platform strategy and making decisions about particular vendor products and technologies
• Specifying the management, operations, and quality of service-security, reliability, and availability-characteristics of the SOA
• Establishing criteria for SOA project design reviews

In addition, a key aspect of SOA architecture governance is defining a roadmap that will guide the smooth and orderly evolution of the architecture over time. The majority of corporate SOA strategies will involve overlaying and transforming the existing systems architecture in stages, rather than a wholesale replacement of the current infrastructure. Governance is needed to ensure that decisions made along the way align in a consistent direction and maintain the coherency of the SOA architecture.

SOA architecture governance is a discipline that architects and IT organizations will acquire with relative ease if they have experience in parallel areas of distributed systems architecture, for example, establishing the architecture of an enterprise-wide integration infrastructure. In contrast, when it comes to the second frontier of SOA governance, organizations are likely to encounter certain requirements for the first time.

Service Life-Cycle Governance
A fundamental underpinning of SOA is that it involves the creation of discrete, well-defined services that exist not only as building blocks of larger systems and applications, but as independent entities. For the first time within the IT environment, SOA exposes standalone application functionality at a fine-grained level of granularity, thus necessitating a new form of governance-service-level governance.

Service-level governance applies at the level of individual services and covers a wide gamut of requirements and situations. A useful approach to categorize the scope of activities associated with service-level governance is to consider the life-cycle of a service - from its design, to its use in a runtime environment, to ongoing management and change of the service - as well as the constituencies who have a vested interest in governance of services.

Design-Time Governance
Design-time governance is primarily an IT development function that involves the application of rules for governing the definition and creation of Web services. Policies might include ensuring that services are technically correct and valid, and that they conform to relevant organizational and industry standards. Examples of this type of validation might include checking that a service is compliant with the Web Services Interoperability (WS-I) profiles - usage guidelines that ensure Web services implemented on different platforms are interoperable - by automatically verifying service schemas, validating namespaces, and other such controls.

If an organization has an SOA governance infrastructure in place - in the form of software that facilitates the implementation of SOA governance practices - these checks can be invoked automatically when developers check services into a registry. In addition, approval and notification workflows can be triggered by a governance-enabled registry to ensure that services pass through pre-defined review and approval steps so that they meet architectural and organizational standards for business function encapsulation, reusability, reliability, and so on. By ensuring that these reviews are performed by appropriate members of the organization, it becomes possible to manage the quality and coherency of the service portfolio effectively.

Design-time governance will be of most concern to business analysts, architects, and developers building services. Key issues to consider include:

• Determining the fitness of a service as an enterprise class asset (where fitness is a function of the business functionality that is encapsulated, the likelihood of reuse, and the importance of the service within the overall portfolio of services)
• Identifying which services to build against the backlog of business requirements
• Ensuring the strategic design of business services and ensuring that their interfaces and implementation conform to established design patterns and other corporate standards and best practices
• Establishing the governance standards to which different categories of services will be held, understanding that different levels of governance will be appropriate for different classes of services (internal use vs. services exposed to business partners, for example)

Other capabilities of design-time governance include fine-grained access control over assets in the registry, so that only authorized users are able to publish, search, and view services. In addition, the ability to label services and classify providers and consumers makes it possible to have some services visible to certain classes of service consumers and not others, a feature that is particularly important for partitioning access in a shared services model.

Runtime Governance
Runtime governance is primarily of interest to IT operations. Governance at runtime revolves around the definition and enforcement of policies for controlling the deployment, utilization, and operation of deployed services. These runtime policies typically relate to non-functional requirements such as trust enablement, quality of service management, and compliance validation. Examples of runtime governance include:

• Checking a service against a set of rules before it is deployed into production, for example, to ensure that only a certain message transport or specific schemas are used by services
• Securing services so that they are accessible only to authorized consumers possessing the appropriate permissions, and that data is encrypted if required
• Validating that services operate in compliance with prescribed corporate standards, in effect, to confirm that a service is not just designed to be compliant, but that its implementation is actually compliant

A more specific case of runtime governance involves service-level monitoring and reporting. In order for the runtime SOA infrastructure to assess whether a given service is performing at the required level for a given consumer - in terms of response time, throughput, and availability - it is necessary to have an explicitly defined service level agreement (SLA) between the service consumer and provider. SLAs can be expressed in terms of service contracts between consumer-provider pairs, and they establish the reference points for compliance monitoring and reporting by the SOA runtime environment. By tracking the actual performance of a service and comparing it to the requirements specified in the SLA, the system can identify non-compliant services and prompt remedial action (for example, automatically instantiating another instance of the service to improve load-balancing or alerting operations staff).