Web Services - Concepts, Architecture and Applications Part 1: Introduction to Web servicesMotivation for the courseObjectives of the courseTwo competing views of Web services bottom up: application integration top down: business exchangesWS architecture: application integrationWhy is it bottom up?ebXML architectureebXML architecture: electronic commerceWhy is it top down?Background for these viewsHow did we get there: the evolution of the architecture of information systemsBasic concepts and notationDistribution at the different layersA game of boxes and arrowsArchitectures (1): fully centralizedArchitecture (2): 2-tier systemTechnical aspects of the 2-tier architectureThe client is always rightMiddlewareArchitecture (3): 3-tier system3-tier middleware architectureMessage oriented middleware (EAI)Extending information systems to communicate through the InternetThe service worldRemote clientsBusiness to Business (B2B)The next step ...The message worldDocuments rather than methodsProcesses rather than service callsThe next step ...Further readingWeb Services - Concepts, Architecture and Applications Part 1: Introduction to Web servicesMotivation for the courseObjectives of the courseTwo competing views of Web services bottom up: application integration top down: business exchangesWS architecture: application integrationWhy is it bottom up?ebXML architectureebXML architecture: electronic commerceWhy is it top down?Background for these viewsHow did we get there: the evolution of the architecture of information systemsBasic concepts and notationDistribution at the different layersA game of boxes and arrowsArchitectures (1): fully centralizedArchitecture (2): 2-tier systemTechnical aspects of the 2-tier architectureThe client is always rightMiddlewareArchitecture (3): 3-tier system3-tier middleware architectureMessage oriented middleware (EAI)Extending information systems to communicate through the InternetThe service worldRemote clientsBusiness to Business (B2B)The next step ...The message worldDocuments rather than methodsProcesses rather than service callsThe next step ...Further readingWeb Services - Concepts, Architecture and ApplicationsPart 1: Introduction to Web servicesGustavo Alonso and Cesare PautassoComputer Science DepartmentETH Zü[email protected]://www.inf.ethz.ch/~alonso©ETH Zürich Part 1: EAI 2Motivation for the courseOverview of technology Web services have not appeared out of the blue but are the result of the natural evolution of middleware and enterprise application integration platforms as they try to leverage the WWW, the Internet and the globalization of society as a whole, particularly in its economic aspects  A key to understanding Web services, how they are and how they might evolve is understanding how we got there and what the relation of Web services with existing technology is. This relation is inescapable as only from this perspective is it possible to understand what is happening in the Web services world. Web services Web services have captured the attention of many companies and vendors. We are currently witnessing a flurry of activity almost without precedent in the computer industry. New proposals appear every month, many of them never to be heard of again. The nature of Web services and the motivation to use them is often blurred by hype as well as the many contradictory and overlapping proposals and specifications out there. The questions we will try to answer in this course are: what are Web services? What can be done with Web services today?©ETH Zürich Part 1: EAI 3Objectives of the courseUnderstanding Web services In order to understand Web services, we need to take a step back and look at the way middleware and enterprise application integration technology has been evolving in the last decades. Only so we will then be able to understand Web services. The most popular version of Web services (SOAP, UDDI, and WSDL) is a very poor and limiting view on what true Web services should be. Alternative proposals such as ebXML, xCBL, or RosettaNetprovide a much deeper insight on what is needed for electronic commerce through Web services.Putting Web services into perspective We will go over the basic Web service technology available today and discuss SOAP, UDDI and WSDL in detail. We will also discuss what can be done with these specifications and what is missing nowadays for them to be truly useful tools for electronic commerce. The course aims at developing a critical understanding of Web service technology and its possibilities today. The goal is for participants to be able to look at current and future developments with enough background to be able to judge how much of a contribution they are and what their true potential is.©ETH Zürich Part 1: EAI 4Two competing views of Web servicesbottom up: application integrationtop down: business exchanges©ETH Zürich Part 1: EAI 5WS architecture: application integration A popular interpretation of Web services is based on IBM’s Web service architecture based on three elements: Service requester: The potential user of a service Service provider: The entity that implements the service and offers to carry it out on behalf of the requester Service registry: A place where available services are listed and which allows providers to advertise their services and requesters to query for services  The goal is just-in-time integration of applications by discovering and orchestrating network-available services©ETH Zürich Part 1: EAI 6Why is it bottom up? The Web service architecture proposed by IBM is based on two key concepts:¾ architecture of existing synchronous middleware platforms¾ current specifications of SOAP, UDDI and WSDL The architecture has a remarkable client/server flavor It reflects only what can be done with¾ SOAP (Simple Object Access Protocol)¾ UDDI (Universal Description and Discovery Protocol)¾ WSDL (Web Services Description Language) UDDISOAPWSDL©ETH Zürich Part 1: EAI 7ebXML architectureebXML compliantsystemBusiness ProfilesBusiness ScenariosebXMLRegistryXMLRequest Business Details1Build Local SystemImplementationRegister Implementation DetailsRegister COMPANY A Profile325Agree on Business Arrangement4Query about COMPANY A profileDownloadScenarios and ProfilesDO BUSINESS TRANSACTIONS6COMPANY ACOMPANY BebXML compliantsystemBusiness ProfilesBusiness ScenariosebXMLRegistryXMLRequest Business