1. Web Services Based on SOA: Concepts, Technology, Design by Thomas Erl MIS 181.9: Service Oriented Architecture 2 nd Semester, 2011-2012

2. Web Services ► web-based applications that use open, XML-based standards and transport protocols to exchange data with clients

3. What are web services? ► Web services are application components ► Web services communicate using open protocols ► Web services are self-contained and self- describing ► Web services can be discovered using UDDI ► Web services can be used by other applications ► XML is the basis for Web services

4. How does it work? ► The basic Web services platform is XML + HTTP. ► XML provides a language which can be used between different platforms and programming languages and still express complex messages and functions. ► The HTTP protocol is the most used Internet protocol.

5. Web services model Web Service Provider Web Service Registry Web Service Client publish bind/invoke find

6. Web Services ► Technology Framework ► Includes one or more of the following: ► Architectures ► Technologies ► Concepts ► Models ► Sub-frameworks

7. Web Services Framework ► Characterized by ► Web services, service descriptions, messages ► Communications agreement (service description) based on WSDL ► Messaging framework using SOAP ► Service description registration and discovery architecture using UDDI

8. Web services platform elements ► SOAP (Simple Object Access Protocol) ► UDDI (Universal Description, Discovery and Integration) ► WSDL (Web Services Description Language)

9. Web services platform elements UDDI WSDL SOAP XML Service Discovery and Publication Service Description XML based messaging Data level description

10. Why use web services? ► Interoperability has Highest Priority ► Web Services take Web-applications to the Next Level ► Web Services have Two Types of Uses ► Reusable application-components. ► Connect existing software.

11. What is SOAP? ► stands for Simple Object Access Protocol ► an XML-based protocol to let applications exchange information over HTTP ► a protocol for accessing a Web Service

12. What is SOAP? ► a communication protocol ► a format for sending messages ► designed to communicate via Internet ► platform independent ► language independent ► based on XML ► simple and extensible ► SOAP allows you to get around firewalls ► SOAP is a W3C standard

13. What is WSDL? ► an XML-based language for locating and describing Web services ► stands for Web Services Description Language ► based on XML ► used to describe Web services ► used to locate Web services ► a W3C standard

14. What is UDDI? ► a directory service where companies can register and search for Web services ► stands for Universal Description, Discovery and Integration ► a directory for storing information about web services ► a directory of web service interfaces described by WSDL ► communicates via SOAP ► built into the Microsoft.NET platform

15. Web Services Design Concepts ► Web service can have two classifications ► Temporary based on roles assumed during runtime ► Permanent based on application logic it provides

16. Web Service Roles ► Web service can assume different roles depending on context of usage ► Message Initiator ► Message Relayer ► Message Recipient ► Agnostic services

17. Service Roles ► Service Provider ► Recipient of the request message ► Service Requestor ► Any unit of processing logic capable of issuing a request message ► Searches for provider by reviewing Service Descriptions ► Web Service is always a provider but can also be a requestor

19. Other roles ► Intermediaries ► Service composition member

20. Intermediaries ► Web services communications is based on use of messaging paths ► Vs. point-to-point communication ► message sent by a requester can be processed by multiple intermediate routing and processing agents before received by ultimate destination ► Intermediaries: web services that route and process a message ► After initially sent ► Before target destination

21. Service Composition Member ► Any service can enlist one or more additional services to complete a given task ► Any of the enlisted services can call other services to complete a given sub-task

22. Service Models ► Application logic classification ► Business-related roles within a solution ► Business service model ► Utility service model ► Controller service model

23. Business Service Model ► Most fundamental building block within SOA ► Encapsulates distinct set of business logic

24. Utility Service Model ► Any generic service designed for potential reuse ► Used in SOA as: ► Services that are reused ► Solution-agnostic intermediary services ► Services with highest degree of autonomy ► Most commonly associated with the application service layer

25. Controller Service Model ► Assembles and coordinates service compositions ► Used in SOA ► To support and implement principle of composability ► To leverage reuse opportunities ► There can be master controller and sub- controller services

26. Service Descriptions ► WSDL used to define service descriptions ► Required to accompany any web service ► Service requestor uses WSDL of a service provider to ensure that messages sent is understood and accepted

27. Service endpoints ► WSDL describes the point of contact for a service provider ► Provides definition of endpoint interface ► So requestor can know how to structure request message ► Establishes the physical location (address) of the service

28. WSDL Definition ► Abstract Definition ► Interface characteristics ► Technology Independent ► portType/interface ► operation ► Represents a specific action performed by a service ► Similar to public method ► message

29. WSDL Definition ► Concrete Description ► Binding ► Technology transport ► E.g. SOAP ► Port/endpoint ► Physical address

30. SOAP ► Header ► Meta information on how data will be delivered and processed ► Allows SOAP messages to be independent ► Sample instructions ► Processing ► Routing/workflow ► Security ► Body ► XML formatted data

32. Service Description Advertisement and Discovery ► UDDI ► One standard for structuring registries that keep track of service descriptions ► Registries can be searched manually or automatically thru an API ► Public Registries ► Accept registration from any organizations ► Private Registries ► Can be implemented within an organization

33. UDDI Registry Records Components ► Business entities ► For public registry records ► Profile of business entity ► Services offered by the entity ► Binding information ► Can be an address of a web site ► Can be a pointer to actual service descriptions