d on the idea of any type of message provision of service, it is most often used in Web environments and based on Web standards [17], such as HTTP, XML, SOAP, BPEL, WSDL, or UDDI. SOA is characterized by the following properties: A logic view. It is an abstraction of services such as programs, databases, and business processes within the application. They are defined in terms of what they do. Thus, its basic components are the services that imple- ment the business logic and the basic functionality of the system. © 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security Message oriented. As part of the services description, the exchanged messages between suppliers and applicants are defined. The internal structure of the service (programming language, internal processes, etc.) remains hidden at this level of abstraction. Description oriented. A service is described in processable metadata. The description supports the public nature of SOA. Only those public details are included in the description and are important for the use of the service. Thus, a simple Web service is characterized by four stan- dards: XML, SOAP, WSDL, and UDDI, which work according to the basic model request / response. Granularity. Services tend to use a small number of operations with relatively complex messages. Network oriented. Services tend to be used over a network, although this is not a prerequisite. Platform independent. Messages are delivered in a standard format and neutral to the platform (usually XML). SOA is associated with a client-server relationship between software modules, where services are subroutines serving customers. However, not all environ- ments and software topologies fit this model, such as advanced multimedia services. With SOA 2.0, an event-oriented architecture is deployed, in which software modules are related to business components, and provide alerts and notifications events. 2.3.1 SOA and SIP Convergence The goal of the SOA and SIP convergence is to offer an infrastructure to