Transcript Web service
Presentation 7 part 1: Web Services Introduced Outline • • • • Definition Overview of Web Services Examples Next Time: SOAP & WSDL Slide 2 Ingeniørhøjskolen i Århus Web Service Defined • W3C definition: – [Definition: 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.] Slide 3 Ingeniørhøjskolen i Århus Overview SOAP & Web services • SOAP – Simple Object Access Protocol - & Web services: – A light-weight & ultra heterogenic alternative to CORBA, DCOM & RMI – Openness in focus – meant for opening legacy applications for others – Not meant in the role of Inter business, large scale, transaction heavy communication (as CORBA & J2EE) – But can prob. be used for it! – Does not have services for transactions, concurrency, persistence, scalability – Does have discovery services (UDDI) giving some degree of location transparency – Does have Interface Definition Language for heterogeneity (WSDL) – Fails on several of the dist. system requirements! – But easy to implement yourself! Slide 4 Ingeniørhøjskolen i Århus Why SOAP When We Have CORBA? • CORBA has been considered too complex by many – May not be true with new development tools using wizards • They aim at solving different tasks: – SOAP covers light-weight application integration within the enterprise, exposing legacy business objects across enterprises, and sharing resources (like Google Search Engine, or Sonofon SMS/MMS API) on the net, as well as technology openness – CORBA has a wide range of services for (as we shall see later): • • • • • Locating, creating & moving objects Object relationship management between hosts Persistency services – activation frameworks etc. Distributed concurrency and transaction management Security – Only some are supported in SOAP tech family – its lightweight – Lesson: define your needs – and find the right technology Slide 5 Ingeniørhøjskolen i Århus Regarding SOAP • SOAP is not by it self revolutionary – its merely: – a framework for exchanging XML-based information in a network (via protocols of the TCP/IP family) – with RPC capabilities – the currently most hyped XML / Web service technology • But when combined with other technologies like – WSDL & – UDDI – It solves several of the requirements of a Distributed System • And the fact that it is an open standard – supported by all major software vendors and programming languages: – C++ – Java – C# – Delphi – Visual Basic and many more • Makes it somewhat revolutionary! A practical solution – like WWW Slide 6 Ingeniørhøjskolen i Århus Overview SOAP & Web services • SOAP – Simple Object Access Protocol - & Web services: – A light-weight & ultra heterogenic alternative to CORBA, DCOM & RMI – Openness in focus – meant for opening legacy applications for others – Not meant in the role of Inter business, large scale, transaction heavy communication (as CORBA & J2EE) – No services for transactions, concurrency, persistence, scalability – Discovery services (UDDI) giving some degree of location transparency – Interface Definition Language for heterogeneity (WSDL) – Fails on several of the dist. system requirements! – But easy to implement yourself! Slide 7 Ingeniørhøjskolen i Århus Why SOAP When We Have CORBA? • CORBA has been considered too complex by many – May not be true with new development tools using wizards • They aim at solving different tasks: – SOAP covers light-weight application integration within the enterprise, exposing legacy business objects across enterprises, and sharing resources (like Google Search Engine, or Sonofon SMS/MMS API) on the net, as well as technology openness – CORBA has a wide range of services for (as we have seen): • • • • • Locating, creating & moving objects Object relationship management between hosts Persistency services – activation frameworks etc. Distributed concurrency and transaction management Security – Only some are supported in SOAP tech family – its lightweight – Lesson: define your needs – and find the right technology Slide 8 Ingeniørhøjskolen i Århus Regarding SOAP • SOAP is not by it self revolutionary – its merely: – a framework for exchanging XML-based information in a network (via protocols of the TCP/IP family) – with RPC capabilities – the currently most hyped XML / Web service technology • But when combined with other technologies like – WSDL & – UDDI – It solves several of the requirements of a Distributed System • And the fact that it is an open standard – supported by all major software vendors and programming languages: – C++ – Java – C# – Delphi – Visual Basic and many more • Makes it somewhat revolutionary! A practical solution – like WWW Slide 9 Ingeniørhøjskolen i Århus Examples of Web Services • Google's Web Service - access the Google search engine – http://www.google.com/apis/ • Amazon's Web Service - access Amazon's product information – http://associates.amazon.com/exec/panama/associates/join/develo per/resources.html • XMethods - collection of information about existing Web services – http://www.xmethods.com • SalCentral - WSDL / SOAP Web services search-engine – http://www.salcentral.com/salnet/webserviceswsdl.asp Slide 10 Ingeniørhøjskolen i Århus Google Web Service Slide 11 Ingeniørhøjskolen i Århus Service-Oriented Architecture (SOA) Opening up for doing business (the sharing of objects) on the Internet Server 3 Client Legacy code on server 1 Abstract Architecture - Web service stack 2 Registry Slide 12 Ingeniørhøjskolen i Århus Technologies for Implementing SOA SOAP for communication WSDL for contract & binding UDDI & WSDL for registration & discovery Slide 13 Ingeniørhøjskolen i Århus