Web Services By Ethan Justin Yuli

Web Services in Action Information through Integration (Google Example)Google Example What do Web Services offer developers, businesses and consumers?

Web Services in Action (continued) Google.com –Google Web APIs service gives you query access to Google's web search, giving developers access to billions of web documents that are constantly refreshed –Developers receive results as structured data, can access information in the Google cache, and check the spelling of words –Examples of use: Issuing regularly scheduled search requests to monitor the web for new information on a subject Performing market research by analyzing differences in the amount of information available on different subjects over time Searching via non-HTML interfaces, such as the command line, pagers, or visualization applications Creating innovative games that play with information on the web

Web Services in Action (continued) Amazon.com –Add thousands of products available through Amazon.com to your own website and earn referral commissions for sales –List hundreds of thousands of products on your site available through Amazon.com affiliates and customize the content so products match the theme of your web site –Dynamically maintain product listings to give visitors current information

Presentation-Outline Topics –SOAP and REST –WSDL –UDDI Summary Questions

Web Service-Overview Web services facilitate the automated transfer of information from Computer A to Computer B using the XML language. This can be accomplished in a number of ways, but for today we’re focused on ‘Standards’ based approaches

Web Services- Two Approaches There is a division in the web community about the best method for accessing resources over the internet. The two leading methods are SOAP, a standards-based approach, and REST

Web Services-SOAP Standards Based Approach Definition: Simple Object Access Protocol Function: SOAP is an envelope that a request for resources is packaged in. It includes a header and body. –The header can include information about security, recipients, handling, routing, etc. –The body includes a standard XML request

Web Services-REST Non-Standards Based Approach Definition: Representation State Transfer Function: REST is an architectural style for accessing distributed media or resources.

Summary of REST and SOAP REST –Messages are represented in plain XML –HTTP is used for the transfer protocol –HTTP verbs are used for access/manipulation commands –URIs are used to uniquely identify resources in message –HTTP authentication provides security –There is no formal method for expressing the interface contract SOAP –Messages are represented in a standardized XML SOAP "envelope" –Can be bound to various protocols including HTTP and SMTP –Access to and manipulation of data are application specific –Security is not described by SOAP and is to be provided by the developer –XML schemas or DTD are used to define the contract between client and service

Web Services Description Language (WSDL) WSDL is a language for describing the capabilities of Web services –In order for computer A to request information from computer B it must know the appropriate method for “asking the question” –Essentially, a WSDL document describes how to invoke a service and provides information on the data being exchanged, the sequence of messages for an operation, protocol bindings, and the location of the service. –WSDL is an integral part of UDDI, an XML-based worldwide business registry

Web Services-UDDI (Yellow Pages for Web Services) Definition: Universal Description Discovery and Integration Function: The UDDI specifications define a registry service for Web services and for other electronic and non-electronic services. A UDDI registry service is a Web service that manages information about service providers, service implementations, and service metadata. –Service providers can use UDDI to advertise the services they offer. –Service consumers can use UDDI to discover services that suit their requirements and to obtain the service metadata needed to consume those services.

Key Topics to Remember Summary –WSDL: Standards-Based Description language for making resource requests –SOAP: Standards-Based Envelope for delivering the request –REST: Messages are represented in plain (pure) XML only –UDDI: Voluntary registry for listing and finding web services (Yellow Pages)

Questions??