1. THE WEB AND WEB SERVICES
„REST in practice“, chapter 11
Lii Nuut
Irma Sauga

2. TOPICS SOAP and it’s processing model WSDL and WADL
Security and end-to-end model
WS-Trust, WS-Federation
HTTPS
HTTP status codes and methods
REST vs SOAP

3. ARE WEB SERVICES EVIL? SOAP-based became popular in 2000
Changed the enterprise integration landscape
Nowadays have perceived heavyweigth and destructive nature

4. SOAP Lightweight Describes for transferring messages: XML envelope
processing model

5. PROCESSING MODEL
SOAP over HTTP is the only widely accepted binding to-date
Can be routed through multiple intermediaries
Low-level messaging protocol

6. HTTP ENVELOPE VS SOAP ENVELOPE
POST /orders HTTP/1.1
Host: restbucks.com
Content-Type: application/vnd.restbucks+xml
Content-Length: 32064
<order xmlns=" …/>
SOAP
<soap:Envelope xmlns:soap="
<soap:Header>
<wsa:To xmlns:wsa=" </wsa:To>
</soap:Header>
<soap:Body>
<order xmlns=" .../>
</soap:Body>
</soap:Envelope>

7. HTTP HEADER VS SOAP HEADER
POST /orders HTTP/1.1
Host: restbucks.com
Content-Type: application/vnd.restbucks+xml
Content-Length: 32064
<order xmlns=" …/>
SOAP
<soap:Envelope xmlns:soap="
<soap:Header>
<wsa:To xmlns:wsa=" </wsa:To>
</soap:Header>
<soap:Body>
<order xmlns=" .../>
</soap:Body>
</soap:Envelope>

8. HTTP BODY VS SOAP BODY HTTP SOAP POST /orders HTTP/1.1
Host: restbucks.com
Content-Type: application/vnd.restbucks+xml
Content-Length: 32064
<order xmlns=" …/>
SOAP
<soap:Envelope xmlns:soap="
<soap:Header>
<wsa:To xmlns:wsa=" </wsa:To>
</soap:Header>
<soap:Body>
<order xmlns=" .../>
</soap:Body>
</soap:Envelope>

9. INTERMEDIARIES AND FAULTS
HTTP and SOAP support intermediaries between sender and receiver of messages
Web deals with faults using 4xx and 5xx response codes from HTTP
SOAP faults are often used to transfer programming exceptions between services and consumers

10. WSDL Language that provides a model for describing web services
Mostly used as verbose object IDL
Has all of the operations that a Web Service supports declared
Maps directly onto the equivalent Java code

11. WSDL AND JAVA
<wsdl:portType name=″ordering″> <wsdl:operation name=″placeOrder″> <wsdl:input message=″restbucks:Order″/> <wsdl:output message=″restbucks:OrderConfirmation″/> <wsdl:fault name=″fault″ message=″restbucks:OrderException″/> </wsdl:operation> <wsdl:operation name=″cancelOrder″> <wsdl:input message=″restbucks:Cancellation″/> <wsdl:output message=″restbucks:Cancelled″/> <wsdl:fault name=″fault″ message=″restbucks:NoSuchOrderException″/> <wsdl:fault name=″fault″ message=″bank:OrderAlreadyServedException″/> ... </wsdl:portType>
public class OrderingService { public OrderConfirmation placeOrder(Order order) throws OrderException { ... } public Cancelled cancelOrder(Cancellation cancellation) throws NoSuchOrderException, OrderAlreadyServedException {

12. WSDL
Tight coupling between the service’s contract and its implementation
Change to the domain model will likely break existing consumers
Solution: Service model between the domain model and the WSDL contract

13. WADL Web Application Description Language
Created to make building and consuming Web- based services accessible to a wide community of programmers
Many of the same problems as WSDL
Also duplicating the metadata available from the resources

14. SECURITY A suite of XML cryptographic tecniques
Transferring SOAP messages between services
Encrypt any part or the whole of the outgoing message
End-to-End model

15. END-TO-END MODEL Based on public key cryptography Transfer protocol
Safely away from the Internet

16. SECURING LONG-LIVED CONVERSATIONS
Shared key to transfer multiple messages
The secure session starts when the consumer and Web Service established a Security Context Token (SCT)

17. WS-TRUST
Token – video store membership cards, passports and OpenID URL- s
WS-Trust defines extensions to WS-Security that provide methods for issuing, renewing and validating security tokens.

18. SINGLE SIGN ON WITH WS-FEDERATION

19. HTTPS Creates a secure transport channel
Simpel point-to-point mechanism for transport security

20. RELIABLE MESSAGING Schemas for reducing message delivery errors:
At most once
Duplicate messages will not be delivered, but messages may still be dropped.
At least once
Every message will be delivered, but duplication may occur.
Exactly once
Every message will be delivered once and once only.
In order
Messages will be received in the same order they were sent.

21. HTTP STATUS CODES 200 - OK 201 - Created 404 - Not Found
405 - Method Not Allowed
409 - Conflict
500 - Internal Server Error

22. REST WEB SERVICE HTTP METHODS

23. WEB TRANSACTIONS POST
Creating a transaction resource

24. WEB TRANSACTIONS GET
Listing current participants and participant statuses with GET

25. REST VS SOAP REST Lightweight - not a lot of extra xml markup SOAP
Human Readable Results
Easy to build - no toolkits required
Yahoo, Flickr
SOAP
Easy to consume - sometimes
Rigid - type checking, adheres to a contract
Development tools
Google, Blogger

26. THANK YOU!
Questions?