SpringPeople Introduction to JAVA Web Services

SpringPeople Introduction to JAVA Web Services

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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved.© SpringPeople Software Private Limited, All Rights Reserved. Introduction to JAVA Web Services
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. What are Web Services? • Web Services are used to build interoperable distributed services across different platform. – The client and server can be developed on different platforms and in different languages, yet they can exchange requests and responses. – For example, a Java client can consume a .NET based service and vice- versa • Legacy or new systems can be integrated rather easily by exposing them as web services. – A better ROI from every system can be achieved.
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Typical Distributed Architecture
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Distributed Architecture Examples • Java Platform – RMI (Remote Method Invocation), EJB (Enterprise Java Beans), CORBA, now not so famous • @Remote interface as the interface • @SessionBean as implementation • JNDI Directory as the registry • JBoss as the service container & publisher • InitialContext.lookup() for fetching proxy on the client side • COM/DCOM on Microsoft platform
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Major Shortcomings of Distributed System •Both client and server must be on the same platform Clients on other platforms can not utilize the services Changes in server-side environment affect all the clients •Client must have server side API for interaction Client can not be developed unless the API is distributed Often the API may be priced, poorly documented and etc., •The protocol between client and server is also platform specific and often proprietary Client that wants to connect to several remote objects have to implement all the specified protocols
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Web Service Architecture Solution
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Web Services Standards • Web Services are build on three foundation standards – Web Service Definition Language (WSDL): An XML based IDL to describe the service definitions in a language agnostic way – Service Oriented Architecture Protocol (SOAP): An XML based PDU for communication between the clients and services – Universal Description Discovery and Integration (UDDI): An XML based registry for service publication and discovery • Bodies like OASIS proposed and publicized other standards as well – Standards like WS-Address, WS-Security, WS-Authentication and etc., are built on top of foundation standards
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Web Service Definition Language (WSDL) What is WSDL? • Its an IDL for describing a web service interface. • The service is meant for the clients of any platform. • Its XML based. Who develops them? • WSDL is hand-written in Contract-First Approach • WSDL is generated in Contract-Last Approach
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. What WSDL consists of? An abstract section • Types: Describes the XML types & elements that are used in the messages to/from the web services. • Messages: Describes the input, output and fault messages that comes into and goes out of web service operations. • PortType: Names the web service and describes the operations offered by the web service A concrete section • Bindings: Describes the transport protocol like HTTP to carry the SOAP envelope for communicating with web service. • Service: Describes the endpoint where the service is really available for consumption
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. SOAP/XML What is SOAP? • It stands for Service Oriented Architecture Protocol in the SOA/Web Services combination. – It originally stood for Simple Object Access Protocol when web services were merely meant for lightweight RPC calls. What is its job? • It carries the payload for request/response between the client and the server. – Obviously its an XML document (JSON is also supported)
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Who writes and consumes SOAP/XML? • Web Service clients/servers dynamically prepares and consumes the SOAP envelopes
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Who carries SOAP and what it consist of? • HTTP or protocol (as specified in WSDL) carries it • It consists of optional Header and mandatory Body
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Web Services v/s SOA •Web Services is one of the technologies to implement Service Oriented Architectures (SOA) However, Web Services predates SOA. Primary intention of web services was to make RPC calls, later it became a technology of choice for SOA implementation •Clients can be developed as an orchestration of services from various endpoints that confirms to SOA Business processes can be delivered in accordance with Software As A Service (SAAS) paradigm. Services needs not be installed at client site, they are just consumed.
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Become a Web Services Expert In 3 Days Flat Attend the 3-Days “Web Services Workshop” View Complete Details
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Who will benefit? Developers and Programmers, who wish to build interoperable distributed services across different platform. View Complete Details
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  © SpringPeople SoftwarePrivate Limited, All Rights Reserved. Q & A training@springpeople.com +91 80 65679700 www.springpeople.com A SpringSource Certified Partner and VMware Authorized Training Center