Presentation 7 part 2: SOAP & WSDL

Ingeniørhøjskolen i Århus Slide 2 Outline Building blocks in Web Services SOA SOAP WSDL (UDDI)

Ingeniørhøjskolen i Århus Slide 3 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 4 Technologies for Implementing SOA SOAP for communication WSDL for contract & binding UDDI & WSDL for registration & discovery

Ingeniørhøjskolen i Århus Slide 5 What is SOAP? Simple Object Access Protocol Akronym no longer spelled out from 1.2 Wire protocol similar to –IIOP for CORBA –JRMP for RMI XML is used for data encoding –“text” based protocol vs. “binary” protocol Supports XML-based RPC

Ingeniørhøjskolen i Århus Slide 6 What is Not SOAP? Not a component model –So it will not replace objects and components, i.e. EJB, JavaBeans and.NET Not a programming language –So it will not replace Java, C# og C++ Not a solution for all –So it will not replace other distributed computing technologies such as RMI and CORBA

Ingeniørhøjskolen i Århus Slide 7 Where is SOAP? W3C XML Protocol working group –SOAP 1.2 current version: –Many only support SOAP 1.1 Microsoft, SUN, Oracle, HP, IBM all support the W3C recommendation –but there are still differences to be overcome –security issues, transactions etc.

Ingeniørhøjskolen i Århus Slide 8 What does SOAP define? Message Envelope Encoding Rules RPC Convention Binding with underlying protocols –HTTP (which we will use in this course) –SMTP –FTP and others

Ingeniørhøjskolen i Århus Slide 9 SOAP Message Format Possible to Attach binaries (images, cryptographic material) to attachments

Ingeniørhøjskolen i Århus Slide 10 SOAP Message Envelope Encoding information Header –Optional –Could contain context knowledge Security Transaction Body –RPC methods and parameters –Contains application data

Ingeniørhøjskolen i Århus Slide 11 Two types of communication

Ingeniørhøjskolen i Århus Slide 12 Request to HelloWorld.jws Input parameters type string HTTP Post Call HTTP Host Target Method name

Ingeniørhøjskolen i Århus Slide 13 … and the HTTP Response from Server HTTP Response Method Response Parameter value Parameter name Apache Tomcat Server Responding

Ingeniørhøjskolen i Århus Slide 14 Issues with SOAP –Lack of business semantics –Insufficient functionality for business operations –Security –Reliability –Under development Low performance

Ingeniørhøjskolen i Århus Slide 15 WSDL WSDL is used for describing WebServices

Ingeniørhøjskolen i Århus Slide 16 What is WSDL? XML language for describing web services Web service is described as – A set of communication endpoints (ports) Endpoint is made of –Abstract definitions of operations and messages –Concrete binding to networking protocol and message format

Ingeniørhøjskolen i Århus Slide 17 Why WSDL? Enables automation of communication details between communicating partners –Machines can read WSDL –Machines can invoke a service defined in WSDL Note that WSDL defines only low-level aspects of Web services, however other technologies might follow … –Security –Transactions –Persistency

Ingeniørhøjskolen i Århus Slide 18 WSDL Document Example Simple service providing stock quotes A single operation called GetLastTradePrice Deployed using SOAP 1.1 over HTTP Request takes a ticker symbol of type string Response returns price as a float

Ingeniørhøjskolen i Århus Slide 19 WSDL Elements Types –Data type definitions –Used to describe exchanged messages –Uses W3C XML Schema as canonical type system

Ingeniørhøjskolen i Århus Slide 20 WSDL Elements Messages –Abstract, typed definitions of data being exchanged Operations –Abstract description of an action –Refers to input and output messages Port type –Collection of operations –Resembles a Class in OOPL

Ingeniørhøjskolen i Århus Slide 21 WSDL Elements Binding –Concrete protocol and data format for a particular Port type –Example: SOAP 1.1, HTTP, MIME Port –Defines a single communication endpoint –Address for binding –URL for HTTP, address for SMTP Service –Aggregate set of related ports

Ingeniørhøjskolen i Århus Slide 22 HelloWorld.jws?wsdl

Ingeniørhøjskolen i Århus Slide 23 UDDI UDDI for publishing & discovery – the SOA

Ingeniørhøjskolen i Århus Slide 24 UDDI Universal Description, Discovery & Integration UDDI defines a scheme to publish and discover information about Web services Programmatic registration and discovery business entities and their Web services Based on SOAP, HTTP, XML Registry data –Business registrations –Service type definitions

Ingeniørhøjskolen i Århus Slide 25 Registration “ White pages” – Address, contact, and known identifiers “ Yellow pages” –industrial categorizations –Industry: NAICS (Industry codes - US Govt.) –Product/Services: UN/SPSC (ECMA) –Location: Geographical taxonomy “ Green pages” –technical information about services

Ingeniørhøjskolen i Århus Slide 26 What uses UDDI? Tool building client (Service Consumer) –Browse or search registry –Create a service proxy Tool publishing the service –Generates WSDL –Construct UDDI entries Application that needs dynamic binding –Directly access UDDI –Query can be pre-generated