Web Service
- A web service is a collection of functions
- Packaged as a single entity and
- Published to the network for use by other programs
- Web services
- Building blocks for creating open distributed systems,
- Allow companies and individuals to quickly and cheaply make their digital assets available worldwide
- A web service can aggregate other web services to provide a higher-level set of features
- Several popular sites provide Web services
- Yahoo, Google, eBay, Amazon, …
W3C Web Services
"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 serialization in conjunction with other web-related standards."
W3C, Web Services Glossary
Basic building Blocks of Web Services
- UDDI (Universal Description, Discovery and Integration)
- Services have to be discovered - http://uddi.xml.org/
- WSDL (Web Services Description Language)
- Interfaces have to be described - http://www.w3.org/TR/wsdl
- SOAP (Simple Object Access Protocol)
- (remote) objects access - http://www.w3.org/TR/soap/
- XML (Extensible Markup Language)
- Data description format - http://www.w3.org/XML/
- HTTP (Hyper Text Transfer Protocol)
- Communication layer - http://www.w3.org/Protocols/