Additional WS specifications
Some specifications have been developed or are currently being developed to extend Web Services capabilities. These specifications are generally referred to as WS-*.
WS-Security (Web Services Security)
WS-Security is a communications protocol providing a means for applying security to Web services (XML Encryption and XML Signature in SOAP to secure message exchanges, as an alternative or extension to using HTTPS to secure the channel).
WS Reliability specifications
- WS-Reliability - is an OASIS standard protocol for reliable messaging between two Web services. Describes a protocol that allows SOAP messages to be reliably delivered between distributed applications in the presence of software component, system, or network failures
- WS-ReliableMessaging (WS-RM) - it is a competing standard to WS-Reliability just supported by a coalition of different vendors. Most of the vendors now support the WS-ReliableMessaging specification
The WS-RM protocol defines and supports a number of Delivery Assurances. These are:
- AtLeastOnce - each message will be delivered to the application destination at least once. If a message cannot be delivered, an error must be raised by the reliable messaging source and/or the reliable messaging destination. Messages may be delivered to the application destination more than once (i.e. the application destination may get duplicate messages).
- AtMostOnce - Each message will be delivered to the application destination at most once. Messages may not be delivered to the application destination, but the application destination will never get duplicate messages.
- ExactlyOnce - Each message will be delivered to the application destination exactly once. If a message cannot be delivered, an error must by raised by the reliable messaging source and/or the reliable messaging destination. The application destination will never get duplicate messages
- InOrder - Messages will be delivered from the reliable messaging destination to the application destination in the order that they are sent from the application source to the reliable messaging source. This assurance can be combined with any of the above assurances.
WS-Transaction
A way of handling transactions.
The WS-Transaction specification describes coordination types that are used with the extensible coordination framework described in the W-Coordination specification. It defines two coordination types: Atomic Transaction (AT) for individual operations, and Business Activity (BA) for long running transactions.
WS client and server communication
Communication between WS client and WS server has been done typically using a SOAP protocol, where WS client passing a SOAP message in a well-formed SOAP request and WS server response back a SOAP message (SOAP response).
