1. Dodick Zulaimi Sudirman www.unimedia.ac.id Lecture 14 Introduction to Web Service Pengantar Teknologi Internet Introduction to Internet Technology

2. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Services Web Services is a software component stored on one computer that can be accessed via method calls by an application or another computer network Web Services protocols and standards are the technology that promote the sharing and distribution of information and business data

3. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Why Use Web Services Easy to create standards-compliant services Does not favor any particular computer language or operating system Output can be transformed for a wide variety of uses It makes a lot of sense for libraries to exploit the Web Service technique

4. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id When to use it Applications do not have severe restrictions on reliability and speed. Two or more organizations need to cooperate –One needs to write an application that uses another’s service. Services can be upgraded independently of clients. –Google can improve PageRank implementation without telling developer. –Just don’t change the WSDL. Services can be easily expressed with simple request/response semantics and simple state. –HTTP and Cookies, for example.

5. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Services Usage Getting stock price information. Obtaining weather reports. Making flight reservations.

6. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Servlets/CGI VS Web Services Browser Web Server HTTP GET/POST DB JDBC Web Server DB JDBC Browser Web Server SOAP GUI Client SOAP WSDL

7. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Services Components Relationship

8. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Services Components Relationship A service broker, acts as a look up service between a service provider and a service requestor. A service provider, publishes its services to the service broker. A service requester, asks the service broker where to find a suitable service provider and that binds itself to the provider.

9. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Services Invocation gdp.globus.org

10. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id UDDI Universal Description, Discovery, and Integration A standard designed to provide a searchable directory of businesses and their Web Services. UDDI is designed like a phone book UDDI business registration consists of three components: –White Pages — address, contact, and known identifiers; –Yellow Pages — industrial categorizations based on standard taxonomies; –Green Pages — technical information about services exposed by the business.

11. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id WSDL Web Service Description Language. –Describes how the service is to be used –Comparabe to Java Interface. –Guideline for constructing SOAP messages. –WSDL is a document written in XML which describes a Web service. It specifies the location of the service and the operations (or methods) the service exposes

12. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id WSDL >>>from SOAPpy import WSDL >>>Server=WDSL.Proxy(‘path/to/WSDL’) >>>server.method.keys() [u’doGoogleSearch’,u’doGetCachedPage’ …] >>>callInfo=server.methods[‘doGoogleSearch’] >>>for arg in callInfo.inparams:... print arg.name, arg.type key (u’http://www.w3.org/2001/XMLSchema’,u’string’)... Define expected messages for a service, and their (input or output parameters). An interface will group together a number of messages (operations) The network location where the service is implemented, e.g. http://localhost:8080 Bind an Interface via a definition to a specific transport (e.g. HTTP) and messaging (e.g. SOAP) protocol

13. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id SOAP Simple Object Access Protocol –protocols used to perform the data transfer between functions which is independent of any runtime environment. –XML Message format between client and service –SOAP is not a transport protocol. You must attach your message to a transport mechanism like HTTP A SOAP message is contained in an envelop. The envelop element in turn contain (in order) –An optional header with one or more child entries. –A body element that can contain one or more child entries. These child entries may contain arbitrary XML data.

14. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id SOAP Headers are really just extension points where you can include elements from other namespaces. Body entries are really just placeholders for arbitrary XML from some other namespace. –The body contains the XML message that you are transmitting.

15. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id SOAP.........

16. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Service Architecture

17. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Service Architecture Service Discovery: Part of the architecture which allows us to find Web Services which meet certain requirements. This part is usually handled by UDDI. Service Description Web Services is self-describing. This means that, once you've located a Web Service, you can ask it to 'describe itself' and tell you what operations it supports and how to invoke it. This is handled by the WSDL.

18. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Web Service Architecture Service Invocation : Invoking a Web Service involves passing messages between the client and the server. SOAP specifies how we should format requests to the server, and how the server should format its responses. Transport : Finally, all these messages must be transmitted somehow between the server and the client. The protocol of choice for this part of the architecture is HTTP, in theory we could be able to use other protocols.

19. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Summary Web Services –Web services can convert your applications into web- applications. –By using XML, messages can be sent between applications UDDI –uses WSDL to describe interfaces to web services WSDL –WSDL is an XML-based language for describing Web services and how to access them. –WSDL describes a web service, along with the message format and protocol details for the web service. SOAP –SOAP is a simple XML-based protocol that allows applications to exchange information over HTTP. –Or more simply: SOAP is a protocol for accessing a web service.

20. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Reference Gunzer, Hartwig. 2002.” Introduction to Web Services”. Borland Garret. 2009. “A short introduction to Web Services”. http://gdp.globus.org/gt3- tutorial/multiplehtml/ch01s02.html akses akhir: 12/10/2010 http://gdp.globus.org/gt3- tutorial/multiplehtml/ch01s02.html Sebesta, Robert. 2009.”Programming the World Wide Web”. Pearson http://onlamp.com/pub/a/onlamp/2007/11 /01/the-mojo-of-dojo.html

21. Dodick Zulaimi Sudirman www.unimedia.ac.id Meet You at The Lab THANK YOU

22. www.dodick-lecture.co.ccDodick Zulaimi Sudirman www.unimedia.ac.id Sumber http://www.pa.icar.cnr.it/cossentino/ICT /doc/D30.1%20- %20A%20short%20introduction%20to %20Web%20Services.pdfhttp://www.pa.icar.cnr.it/cossentino/ICT /doc/D30.1%20- %20A%20short%20introduction%20to %20Web%20Services.pdf http://gdp.globus.org/gt3- tutorial/multiplehtml/ch01s02.htmlhttp://gdp.globus.org/gt3- tutorial/multiplehtml/ch01s02.html http://www.w3.org/TR/wsdl http://www.w3schools.com/soap/ http://www.w3schools.com/wsdl/