Service provider: The service provider provide the service and implements the service. It make the service available on the internet.
Service requestor: This is any consumer of the web service. The requestor utilizes an existing web service by opening a network connection and sending an XML request.
Service registry: Centralized directory of services. It is logically registry provides a central place. At that place developers published new services and find existing services.
Service transport: Service transport is responsible for transporting messages between applications. Its includes hypertext transfer protocol (HTTP), Simple Mail Transfer Protocol (SMTP), file transfer protocol (FTP). Its include something newer protocol named Blocks Extensible Exchange Protocol (BEEP).
Service description: Responsible for describing the public interface to a specific web service. Currently, service description is handled via the Web Service Description Language (WSDL).
Service discovery: Responsible for centralizing services into a common registry. Its provide easy publish and find functionality for the developer. Currently, service discovery is handled via Universal Description, Discovery, and Integration (UDDI).