Web services concepts, protocols and development

1. Web Services: Concepts,
Protocols and development
Prepared By:
Mehta Ishani

2. Outline
• What is a web service?
• Why web service?
• Web Services Model
• Web Services Stack
• What is UDDI?
• What is WSDL?
• What is SOAP?

3. What is a web service?
• Application components accessible over internet
• Once deployed, can be used by other
applications
• XML is the basis for Web services

4. Standard definitions
• IBM
▫ “A Web service is an interface that describes a
collection of operations that are network
accessible through standardized XML messaging”
• Microsoft: XML Web Services
▫ “.. provide a way to describe their interfaces in
enough detail to allow a user to build a client
application to talk to them”

5. History
• Structured programming
• Object-oriented programming
• Service oriented programming
Hewlett-Packard's e-Speak in 1999 was an enabler
for e-services.
Microsoft introduced the name "web services" in
June 2000

6. Why web services?
• Application and data integration
(provides interoperability)
• Versatility
(Any platform, Any Language)
• Code re-use
(provides flexibility)
• Cost savings
(Open Standards)

7. How does it work?
The basic Web services platform is XML + HTTP.
• SOAP (Simple Object Access Protocol)
• UDDI (Universal Description, Discovery and
Integration)
• WSDL (Web Services Description Language)

8. Web services model
Registry
(UDDI)
Service
Requestor
Service
Provider
Find Publish
Bind
(SOAP)
(SOAP)
(WSDL)

9. Web services stack

10. What is UDDI?
• Universal Description, Discovery and
Integration
• UDDI is a directory service where businesses can
register and search for Web services.
• Sponsored by OASIS
• Uses W3C and IETF Internet standards such as
XML, HTTP, and DNS protocols.

11. What is UDDI?
• UDDI registry
• Search for Web service to obtain WSDL
• For ex. Travel agency can use air line reservation
interface
• UDDI Community

12. What is WSDL?
• Web Services Description Language
• XML-based language for describing Web
services and how to access them.
• WSDL is maintained by the W3C.

13. Major elements
• Port type - describes the operations performed
• Port - specifies an address for a binding
• Message – describes name and format of
message
• Types - defines the data types
• Binding - defines the communication protocols
• Service - specifies the address URL

14. What is SOAP?
• Simple Object Access Protocol
• SOAP is a simple XML-based protocol that
allows applications to exchange information
over HTTP.
• SOAP will be developed as a W3C standard

15. Why SOAP?
• RPC does not support HTTP
• compatibility and security problem, firewalls
and proxy servers issues
• HTTP is supported by all Internet browsers and
servers.

16. Major elements
• Envelope –encloses the message itself.
• Header (optional) – contains information
relevant to the message
• Body – includes the message payload.
• Fault (optional) – carries information about a
client or server error within a SOAP message.

17. namespace
• default namespace for the SOAP envelope:
http://www.w3.org/2001/12/soap-envelope
• default namespace for SOAP encoding and data
types is:
http://www.w3.org/2001/12/soap-encoding

18. SOAP HTTP Binding
• HTTP + XML = SOAP
• A SOAP request could be an HTTP POST or an
HTTP GET request.
• Contains two headers
• Content-Type - defines the MIME type
• Content-Length - number of bytes in the body