Presentation 7 part 1: Web Services Introduced

Ingeniørhøjskolen i Århus Slide 2 Outline Definition Overview of Web Services Examples Next Time: SOAP & WSDL

Ingeniørhøjskolen i Århus Slide 3 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.]

Ingeniørhøjskolen i Århus Slide 4 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!

Ingeniørhøjskolen i Århus Slide 5 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

Ingeniørhøjskolen i Århus Slide 6 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

Ingeniørhøjskolen i Århus Slide 7 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!

Ingeniørhøjskolen i Århus Slide 8 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

Ingeniørhøjskolen i Århus Slide 9 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

Ingeniørhøjskolen i Århus Slide 10 Examples of Web Services Google's Web Service - access the Google search engineGoogle's Web Service – Amazon's Web Service - access Amazon's product informationAmazon's Web Service – per/resources.html XMethods - collection of information about existing Web servicesXMethods – SalCentral - WSDL / SOAP Web services search-engineSalCentral –

Ingeniørhøjskolen i Århus Slide 11 Google Web Service

Ingeniørhøjskolen i Århus Slide 12 Service-Oriented Architecture (SOA) Client Server Registry Abstract Architecture - Web service stack Abstract Architecture - Web service stack Legacy code on server Legacy code on server Opening up for doing business (the sharing of objects) on the Internet

Ingeniørhøjskolen i Århus Slide 13 Technologies for Implementing SOA SOAP for communication WSDL for contract & binding UDDI & WSDL for registration & discovery