SOA - Unit 1 - Introduction to SOA with Web Services

Introduction to SOA with Web Services

1. UNIT - 1 INTRODUCTION TO SOA WITH WEB SERVICES

2. SOA An architecture that relies on loosely-coupled software agents to perform specified tasks. Software agents can be independent of one another. Loose-coupling : an approach / design goal where interaction between services is developed . Interface is independent of implementation Service – a unit of work performed by a service provider for a service consumer. Web service – a software system designed to support interoperable machine to machine interaction over a network. SOA web services are typically built on web service standards.

3. SOA Facilitates the composition of services. WSDL – std programming interface to access any application SOAP – std interoperability protocol to connect any application to any other.

4. Key Technologies Extensible markup language (XML) Web services Service-oriented architecture (SOA) Business process management (BPM)

5. Service-oriented development Benefits : Reuse Efficiency Loose technology coupling Division of responsibility Developing a service is different from developing an object. Higher level of abstraction Coarse-grained interface Consumes more computing resources Services are executed by exchanging messages.

6. Service Dividing the responsibilities: Create the services Consume the services It is location on n/w that has a machine-readable description of the messages it receives and optionally returns.

7. Service abstraction

8. Requesting different types of services

9. Service oriented architecture It includes services like(in bank): Account management Loans Withdrawals, deposit and transfer Foreign currency exchange

10. SOA It is a style of design that guides all aspects of creating and using business services. Approach to built IT systems in which business services are the key organizing principle used to align IT systems with the needs of the business. Capitalize on the value of service-oriented development Easy to understand the benefit of reusing common business services. Key to a successful SOA – determine the correct design and function of the services in the reusable service library.

11. Challenges to adoption Ensuring the developed services are reusable. Short-term cost Some appln may need to be modified inorder to participate in the SOA.

12. SOA and web services Advantage: Pervasive Simple Platform-neutral Provides specifications for security, reliability, transactions, metadata management and orchestration.

13. Web service platform

14. Rapid integration

15. Multi channel access

16. Occasionally connected computing Challenges in integrating mobile devices into an SOA: Not always connected to n/w Moves SOAP messages in a mobile software solution

17. Business process management Consisting of a set of logically related task. BPM – set of software systems, tools and methodologies that addresses how organizations identify, model, develop, deploy and manage such business processes. Exploit the foundation and the architectural work. Help align business processes with desirable business outcomes. Separating business process logic from other appln code helps : Increase productivity Reduce operational costs Improve agility

18. BPM Simplifies the pblm Diagram – graph that a business analyst might produce for automating the flow of purchase order processing. Persists the i /p document -> document is validated -> reference is made. Customer may have an opportunity to reconfirm the order, given the quoted price and delivery schedule. Not confirmed -> cancelled. Process flows are broken into individual tasks. Service-based solution - > productivity increases easily, flexible

19. Extended web services specifications SOAP and WSDL QoS Features : Standardization Specification composability Metadata management Security Reliability and messaging Transactions Orchestration

20. Standardization Standardization through a variety of ways. Initially created by Microsoft and IBM Standard bodies that are active in web services: World wide web consortium (W3C) Organization for the Advancement of Structured Information Standards – OASIS Web services interoperability (WS-I) Internet Engineering Task Force (IETF) Java Community Process(JCP) Object Management Group (OMG)

21. Specification composability SOAP and WSDL specifications Combined within a single SOAP message Eg : extended headers for security ( wsse :) and reliability( wsrm : ) Different namespaces ( ie ) duplicate element & attribute – not permitted. May or may not require modification to existing web services Added responsibility of the SOAP

22. Adding extended features to SOAP.

23. Metadata management It includes the description information about a web service. Specifications are: XML Schema WSDL WS-Addressing WS-Policy WS-Metadata Exchange Addressing – important requirement. Policy – necessary for expressing any extended web services features of a service Acquiring metadata – uses WS- MetadataExchange with “actions”

24. Security Apply at every level of the web services specification to guard against the numerous challenges and threads of DC. Built around Encryption Authentication Authorization Comprehensive logging Ws -security SSL & WS-security header Additional specification: WS- SecurityPolicy , WS-Trust, WS- SecureConversation and WS-Federation Technologies: XML Encryption and XML Signature

25. Reliability and messaging Reliability messaging specification: WS-Reliability WS- ReliableMessaging Protocol for exchanging SOAP msgs with Guaranteed delivery No duplicates Guaranteed message ordering Reliable messaging automates recovery Specification: WS-Eventing WS-Notification

26. Transactions Allow multiple operations Has ability to recover an appln Coordination – mechanism for determining a consistent, predefined outcome for composite web service appln Specification: WS-Transactions family WS-Atomic transactions WS- BusinessActivity WS-Coordination WS-Composite Application Framework((WS-CAF) WS-Context WS- CoordinationFramework WS- TransactionManagement

27. Orchestration Used to create more complex interaction patterns Provides an interface that encapsulates a sequences of other web services. WS-BPEL : web services business process execution language Defines an executable language compatible WS-CDL : web services choreography definition language Defined as establishing the formal relationship between two or more external trading partners.