SOA services communicate with messages, which are often defined using XML schemas (also known as XSD, XML Schema definition). Communication between consumers and providers or consumers and services is much more common in environments where providers are not known. Communication between services can also be viewed as a key business document for internal processing within an enterprise.
Within an enterprise, SOA services are maintained through a registry (Registry) that acts as a directory listing (directory listing) role. The application searches for and invokes a service in the registry (Registry). Unified description, definition and integration (UDDI, universal Description, definition, and integration) are standards for service registration. Each SOA service has a service quality associated with it (QoS, quality for service). Some of the key elements of QoS are security requirements (such as authentication and authorization), reliable communication, which ensures that messages are "only" sent once, filtering for duplicate information. And who can invoke the policy of the service.
Why Choose SOA?
Different kinds of operating systems, application software, system software and application infrastructure (application infrastructure) are intertwined, which is the status quo of it enterprises. Some existing applications are being used to handle the current business process (business processes), so it is impossible to build a new infrastructure from scratch. Companies should be able to respond quickly to changes in the business, leveraging existing applications and application infrastructure (application infrastructure) to address new business needs, providing new channels of interaction for customers, business partners, and suppliers, and presents a framework that can support the organic business (organic business). SOA, by virtue of its loosely coupled nature, enables enterprises to add new services or update existing services in a modular manner to address new business needs, provide choices to provide services through different channels, and can serve as services to existing or established applications of the enterprise, thereby protecting existing IT infrastructure investments.
SOA infrastructure
To run, manage SOA applications, the enterprise needs an SOA base, which is part of the SOA platform. The SOA base must support all relevant standards and the run-time containers that are required.
SOAP, WSDL, UDDI
Wsdl,uddi and SOAP are the basic components of the SOA Foundation. WSDL is used to describe services; UDDI is used to register and find services, and soap, as a transport layer, is used to send messages between consumers and service providers. SOAP is the default mechanism for Web services, and other technologies enable other types of bindings to be serviced. A consumer can find a service in the UDDI Registry (registry), obtain a WSDL description of the service, and then invoke the service through SOAP.
SOA is not a Web service
Confusion often occurs in understanding the relationship between SOA and Web services. According to a April 2003 Gartner report, Yefim v. Natis explains this problem: "Web services are technical specifications, and SOA is design principles." In particular, WSDL in Web Services is an interface definition standard for SOA: This is the fundamental link between Web services and SOA. "Essentially, SOA is an architectural pattern, and Web services are services implemented with a set of standards." Web services are one way to implement an SOA. The advantage of using Web services to implement SOA is that you can implement a neutral platform to get services, and you will achieve better versatility as more and more software vendors support more and more Web service specifications.
The advantages of SOA
The concept of SOA is nothing new, and SOA differs from existing distributed technologies in that most software vendors accept it and have platforms or applications that can implement SOA. SOA is accompanied by ubiquitous standards that bring greater reusability to the enterprise's existing assets or investments. SOA can create applications on top of the latest and existing applications; SOA enables customers or service consumers to be exempt from changes in service implementations; SOA can upgrade a single service or service consumer without rewriting the entire application, or retaining existing systems that no longer apply to new requirements. All in all, SOA is an agile way of combining existing applications to generate new services, providing the enterprise with greater flexibility to build applications and business processes.
