Supported Standards
Web Service technology must be based on generally accepted standards. As soon as you link up application modules developed in different programming languages on different hardware and in different systems with the business process using Web Services, you are faced with the very important questions of interoperability and adherence to prescribed standards.
Conventional channels and Internet standards are used for communication. The interface of a Web service is specified using WSDL, remote procedure calls are transmitted using SOAP, and Web Services are determined using UDDI.
Although standards such as SOAP, WSDL, and UDDI have become the general norm, there is still much to be accomplished by standardization committees. Some standards are being newly developed while others are being developed further. Enhanced standards – such as security standards or additional protocols – are continuously updated and integrated into the Web Service Framework by SAP.
General Web Service Specifications:
● SOAP (1.1)
Simple Object Access Protocol (SOAP) provides the definition of the lightweight protocol for XML based information, exchanged between parties in a distributed environment. SOAP version 1.2 supports major features, required for communication with other Web service vendors.
● WSDL (1.1)
Web Service Description Language (WSDL), describes Web services as abstract endpoints operating on messages. The definition of operations and messages is abstract while the binding to a specific network protocol is concrete.
● UDDI (3.02)
Universal Description, Discovery and Integration (UDDI), defines uniform way to publish and to find Web services.
● XML (1.0)
Extensible Markup Language (XML) is a self-descriptive language designed for exchanging structured data over the Internet. It is the foundation of Web services.
● HTTP (1.1)
Hyper Text Transfer Protocol (HTTP) is a lightweight document transfer protocol that provides an effective universal data transfer.
Specifications - Description and Search
● WS-Policy (2004/09)
Defines the model and syntax to describe and communicate the policies of a Web service. A policy is a collection of policy assertions that describe one or more characteristics that a Web service provider requires from a Web service consumer subsequently.
● WS-Policy Attachment (2004/09)
Defines how to attach WS policy assertions to WSDL documents and UDDI descriptions.
Only attachments to WSDL 1.1 are supported.
● WSIL (1.0)
Web Service Inspection Language (WSIL), defines how to locate Web service descriptions on a provider system.
Specifications - Messaging
● WS Addressing (1.0)
Defines a standard mechanism for identifying and exchanging Web services messages between multiple endpoints.
● WS Reliable Messaging (1.1)
Describes a protocol that allows messages to be delivered reliably between distributed applications in the presence of software component, system, or network failures.
Security Specifications
● WS-Security (1.0)
Describes enhancements to SOAP that allow for quality security of SOAP messages including binary tokens for message authentication, digital signatures for message integrity, and content encryption for message confidentiality.
● WS Security: SAML Token Profile (1.0)
● WS Security Policy (1.2)
Defines security assertions detailing a Web service’s requirements that the Web service consumer can meet.
WS-Security Policy is available in PI 7.1 only for SAP to SAP scenarios.
● WS Secure Conversation 1.3
Defines how to establish and maintain a persistent context for a secure session over which multiple Web service invocations might be sent without requiring authentication each time.
WS Secure Conversation is available only for SCT through SSL bootstrap
● SAML (1.1)
Security Assertion Markup Language (SAML) is an XML-based standard for exchanging security information between systems.
Other Specifications
● WS-I Basic Profile (1.1)
Provides interoperability guidance for core Web service specifications, such as SOAP, WSDL, and UDDI.