Web Services provides standard means of interoperating between different software applications, running on a variety of platforms and/or frameworks.
Definition (W3C - Web Service architecture - http://www.w3.org/TR/2004/NOTE-ws-arch-20040211/): « A Web Service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web Service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialisation in conjunction with other Web-related standards. »
Web services definitions offer several options. Table 1 shows the options chosen by the PSMs described in this document.
| Web Service Options | Decision |
| Discovery | Not dynamic : UDDI is not used, the Web Services are described in this DATEX II document which is the reference for development |
| Security | The security set-up has to be decided by the Supplier, should be negotiated with the Clients, and is outside the scope of this specification |
| Encryption | This has to be agreed between the Supplier and the Client, before starting data exchange |
Table 1 Web Services options
Platform Specific Model (PIM) specification to implement FEP+EP PIM based on WS SOAP technology consists in mapping the abstract UML messages ( invocation methods and data types ) defined at FEP+EP PIM level as UML collaboration and sequence diagrams in ISO TS 19468 clauses to the corresponding SOAP WSDL methods and data structure.