1. Presentation 7 part 2:
SOAP & WSDL

2. Outline
Building blocks in Web Services SOA
SOAP
WSDL
(UDDI)

3. Service-Oriented Architecture (SOA)
Opening up for doing business (the sharing of objects) on the Internet 3
Client
Server
Legacy
code on
server 1 2
Registry
Abstract Architecture
- Web service stack

4. Technologies for Implementing SOA
SOAP for communication
WSDL for contract & binding
UDDI & WSDL for registration & discovery

5. What is SOAP? Simple Object Access Protocol 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

6. What is Not SOAP? Not a component model Not a programming language
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

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

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

9. SOAP Message Format
Possible to Attach binaries (images, cryptographic material) to attachments

10. SOAP Message Envelope Encoding information Header Body Optional
Could contain context knowledge
Security
Transaction
Body
RPC methods and parameters
Contains application data

11. Two types of communication

12. SOAP RPC Request Example
<SOAP-ENV:Envelope
xmlns:SOAP-ENV="…"
SOAP-ENV:encodingStyle="…">
<SOAP-ENV:Header>
<!-- Optional context information -->
</SOAP-ENV:Header>
<SOAP-ENV:Body>
<m:GetLastTradePrice xmlns:m=“some_URI">
<tickerSymbol>SUNW</tickerSymbol>
</m:GetLastTradePrice>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

13. SOAP RPC Response Example
<SOAP-ENV:Envelope
xmlns:SOAP-ENV="…"
SOAP-ENV:encodingStyle="…">
<SOAP-ENV:Header>
<!-- Optional context information -->
</SOAP-ENV:Header>
<SOAP-ENV:Body>
<m:GetLastTradePriceResponse xmlns:m=“some_URI">
<price>30.5</price>
</m:GetLastTradePriceResponse>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

14. SOAP RPC composition I Information needed for a method call:
The URI of the target object (marked with red)
<SOAP-ENV:Body>
<m:GetLastTradePrice xmlns:m=“
<tickerSymbol>SUNW</tickerSymbol>
</m:GetLastTradePrice>
</SOAP-ENV:Body>

15. SOAP RPC composition II
Information needed for a method call:
The URI of the target object
The Method Name
<SOAP-ENV:Body>
<m:GetLastTradePrice xmlns:m=“
<tickerSymbol>SUNW</tickerSymbol>
</m:GetLastTradePrice>
</SOAP-ENV:Body>

16. SOAP RPC composition III
Information needed for a method call:
The URI of the target object
The Method Name
Parameters
Binding protocol (next slide)
<SOAP-ENV:Body>
<m:GetLastTradePrice xmlns:m=“
<tickerSymbol>SUNW</tickerSymbol>
</m:GetLastTradePrice>
</SOAP-ENV:Body>
Name is not important

17. SOAP RPC composition IV: complete SOAP RPC Request
STEP 4: BINDING TO PROTOCOL
POST /StockQuote HTTP/1.1
Host:
Content-Type: text/xml; charset="utf-8"
Content-Length: nnnn
SOAPAction: "Some-URI"
<SOAP-ENV:Envelope
xmlns:SOAP-ENV=”
SOAP-ENV:encodingStyle=”
<SOAP-ENV:Body>
<m:GetLastTradePrice xmlns:m="
<tickerSymbol>SUNW</tickerSymbol>
</m:GetLastTradePrice>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
HTTP
Name-space
Encoding

18. Request to HelloWorld.jws
HTTP Host Target
HTTP Post Call
Method name
Input parameters type string

19. … and the HTTP Response from Server
Apache Tomcat Server Responding
HTTP Response
Method Response
Parameter name
Parameter value

20. Issues with SOAP Issues with SOAP Low performance
Lack of business semantics
Insufficient functionality for business operations
Security
Reliability
Under development
Low performance

21. WSDL
WSDL is used for describing WebServices

22. 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

23. 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

24. 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

25. WSDL Elements Types Data type definitions
Used to describe exchanged messages
Uses W3C XML Schema as canonical type system

26. WSDL Elements Messages Operations Port type
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

27. WSDL Elements Binding Port Service
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

28. HelloWorld.jws?wsdl

29. Tools Generate WSDL document from Generate SOAP messages from JAX-RPC
existing Java classes or EJB components
AXIS: Java2WSDL
Generate SOAP messages from
WSDL document (via client stub and server skeleton)
JAX-RPC
Part of J2EE from Sun (needs AS)
IDE Tools:
NetBeans, Eclipse, Forte for Java, JBuilder, JDeveloper
Microsoft:
IIS for services and Visual Studio for IDE

30. UDDI
UDDI for publishing & discovery – the SOA

31. UDDI Universel Descrition, Discovery & Integration
UDDI defines a scheme to publish and discover information about Webservices
Programmatic registration and discovery business entities and their Webservices
Based on SOAP, HTTP, XML
Registry data
Business registrations
Service type definitions

32. Registration “ White pages” “ Yellow pages” “ Green 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

33. 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