With SOA, a service such as ringing a phone, forwarding a call, or conferencing a call is developed as a building block that can easily be modified or integrated into a new application. A change to or addition of a new feature is a change to the building block of the service, unconcerned about how it might impact other functions in the entire software program. Building blocks can also be combined ("mashed up" to use an SOA term) to create new "composite services" or applications.

The major advantage of SOA is the ease with which one service can "talk" to another (by connecting the building blocks, where each block is a service) - without concern or even knowledge of the underlying interfaces or connections. So a business can rapidly link and sequence services in a process known as "orchestration" to meet new or existing business system requirements.

As businesses become more and more dependent on the Web and on instant access to communications and information, the number of business applications that need to know about the network is increasing. If communication functions can be exposed as Web Services that can be integrated to other applications this can create new and exciting applications. In fact, applications will become rich, highly valuable, and transformational for customers when they become highly collaborative and when they interact with and leverage the power of the underlying network.

The challenge is how to do this simply and rapidly.

Ease of Integration
Web Services offer one method of implementing SOA and provide a standardized way (or technology) of integrating Web-based applications using standards-based interfaces such as XML and SOAP. Using Web Services, service or application components can be published to the rest of the world. Web Services support interoperable machine-to-machine (i.e., PC) interaction or communication over a network like the Internet.

The primary protocol used in communicating Web Services is HTTP/HTTPs. SOAP, that's the Service Oriented Architecture Protocol, is the message envelope format and can use HTTP/HTTPS, XMPP, or SMTP as its transport protocol. As a service or application component, Web Services are self-contained and self-describing. They can be discovered using UDDI (Universal Description, Discovery, and Integration), which acts like a registry and describes Web Services so developers can find them easily (to incorporate into other applications). And then there's WSDL (the Web Services Description Language), which provides Web Services interface syntax to facilitate connecting these services to one another. XML (the eXtensible Markup Language) provides a language that can be used between different platforms and programming languages and express complex messages and functions. Web Services use XML to code and decode data and SOAP to transport it using open protocols.

The key advantage of Web Services is that they use standard technologies such as XML, HTTP, SOAP, and WSDL to recognize, identify, and communicate with these building blocks of functions or services to develop new services (composite services) simply and easily.

For example, to increase the capacity of the "my conferencing service" feature now requires a simple code change in the conferencing service building block. The software developer can simply test that single building block, verify that it works, and then launch it as an overall feature of the PBX.

Before SOA, that same software programmer would search for the specific line of code (out of million of lines) that impacted that conference service, make the change, and then follow the impact of the change in other services (i.e., how it connected to other services). Finally, those million lines of codes would be tested then run in the lab for a couple of days in hopes nothing would go wrong. (See Figure 1)

What Are the Business Benefits?
Enterprises that effectively align technology with business goals achieve a competitive advantage. The adoption of Service Oriented Architecture is an effective way to organize the discrete functions contained in enterprise applications into interoperable, standards-based services that can be combined and reused quickly to meet business needs. The IT world is already using SOA and Web Services to facilitate the integration of business processes and business applications.

"Now the world of communications can participate in the integration of business applications and processes," according to Richard Tworek, general manager of SOA and next-generation unified networks at Nortel. "Using SOA frameworks and Web Services standards, vendors like Nortel have developed software that abstracts or exposes communication features from underlying communication network infrastructures (PBXs and communication servers) and presents them as building blocks that can be integrated with other services (IT or telecomm). Thus you can take real communications capabilities such as click-to-connect, IM (instant messaging), and location and presence and integrate them into other business applications and processes creating communication-enabled applications and processes."

A simple example can be communication-enabling your SCM (supply chain management) process. When inventory for a certain item falls below a certain level (say 10% of the monthly average), an IM can be sent to the purchasing officer. Furthermore, you can enact an automatic purchase order to the supplier and IM both supplier and purchasing officer that this has occurred. The benefits of this communications-enabled application or process are speed, accuracy, and agility leading to overall higher productivity and lower costs. This adaptation and interaction between the communications capabilities and the business applications is made easier by the adoption of SOA-based software architectures and Web Services technologies in the communications domain. Communications capabilities can be made available as services that can be combined with IT-based services and reused quickly to meet business needs.

By organizing enterprise IT (with telecom) around services instead of around applications, SOA provides key benefits. It

• Improves business agility, productivity, and speed (for both business and IT)
• Allows IT and telecom to deliver services faster and align closer with business
• Allows the business to respond quicker and deliver optimal user experience
• Masks the underlying technical complexity of the IT, network, and telecom environment

Organizations that have adopted Service Oriented Architecture environments in their IT domains are experiencing dramatic results, including increased revenues, increased customer satisfaction, lower operational costs, and higher returns on their existing technology investments.

In summary, SOA is better because it uses a modular, distributed, building block approach to create, develop, and deliver new products and features faster, more simply, and in a less resource-intensive way. And building blocks can be mixed and matched to create new applications such as communication-enabled applications - providing yet-another benefit besides those already described.