Web Services Partha Goswami 04 IT 6015 1

Overview n What is Web Service n Motivation for web Services n Web Services Architecture n Future Vision and Challenges 2

What Is Web Services Example: Web based purchase itt edi red nse C c Cr eo k p h Cs Re Purchase Invoice Order Credit Service Consolidate Results PO Service In. R ve RIn ento es serry ve po ve nto ns ey r Web services are self contained, self describing, modular applications that can be published, located, and invoked across the web. Web services perform functions, which can be anything from simple requests 3 to complicated business processes". ---- According to IBM Figure Taken from Oracle Session id: 40024

Service Description B B 2 Service Integration Virtual Travel Agency h B Search / Use Directory Service lis b Pu Service Description Features Of Web Services Migration Of Existing web Application Service Description Standards are the Base Communicate using messages B 2 B Robust , Effective, Flexible Security Services Description Web Service Discovery Figure Taken from Intelligent agent course 2003/2004 by Dr. Omar Belakhdar 4

Benefits of Web Service? n n n Create a single, comprehensive, flexible Web platform Utilization existing Infrastructure Web services gives users the option of choosing a particular hardware and software platform without being concerned about the integration cost. Content management systems to store information in a repository where it is easily accessible for reuse Traditional security mechanisms have given way to "entitlement programs" 5

Web Services Meet Business Processes Sales Finance Web Service 1 Web Service 4 Logistics HR Web Service 2 Web Service 5 Support Partners Support Web Service 3 Web Service n Ne twork 6

How widespread they are today? “IDC report, nearly 50% of enterprises interviewed will have implemented Web services by 2006. IDC estimates that 5% of all U. S. enterprises had completed Web Services initiatives by the end of 2002, and it projects that 80% will have some kind of Web services project underway by 2008” “Gartner expects Web services will dominate the deployment of new application solutions for Fortune 500 companies by 2004” “Approximately 79% of companies surveyed in the summer of 2002 planned to implement a Web services project in 2003, according to the Software & Information Industry Association (SIIA) and Systinet Corp. , ” “To not explore investing in some type of Web services initiative at this point would be a mistake. There's a distinct need today for application interoperability, which is the goal of Web services. " says Laurie A. Seymour, a program manager at research firm IDC. Web services "are becoming extremely important, extremely fast, " says Whit Andrews, an analyst in research firm Gartner's Internet platform and Web services group. 7

Web Services Architecture n Architecture can be described in terms of • What goes “on the wire”: Formats and protocols. - XML, SOAP, and WS-Addressing • What describes what goes on the wire: Description languages. - Machine-readable metadata • What allows us to find these descriptions: Discovery of services- Web service discovery • What protocols to use to transport • Specification for enumeration of service resources 12

XML-e. Xtensible Markup Language n n . In Web services, a message is an XML document information item as defined by the XML Information The Information items generally maps to the various features in an XML document, such as elements, attributes, namespaces, and comments …. n There are eleven types of information items in an XML document. n It allows opaque binary data to be interleaved with traditional text-based markup. The W 3 C XML-binary Optimized Packaging (or XOP) format. n SOAP Message Transmission Optimization Method, or MTOM, then specifies how to bind this format to SOAP n XOP and MTOM are the preferred approach for mixing raw binary with textbased XML 13

SOAPn n n Simple Object Access Protocol SOAP provides a simple and lightweight mechanism for exchanging structured and typed information between peers in a decentralized, distributed environment using XML Contains three elements: <Envelope>, <Header>, and <Body>. SOAP Node, original sender , ultimate receiver, intermediary, message path. Message Exchange Patterns: Broadcast transports , Push Model, Pull Model Transport Independence: using HTTP , SOAP-over-UDP 14

Metadata n Metadata enables interoperability. n Describe the message interchange formats the service can support n n n Web Service Description Language, or WSDL, was the first widely adopted mechanism for describing the basic characteristics of a Web service. WSDL may define where the service is available and what communications protocol is used to talk to the service. WS-Policy introduces a simple and extensible grammar for expressing policy 15

Discovery n n Two most common approaches to finding information in a computer system: looking in a well-known location, or broadcasting a request to all available listeners. The Universal Description, Discovery, and Integration protocol, or UDDI, specifies a protocol for querying and updating a common directory of Web service information. n UDDI directory approach can be used when Web service information is stored in well-known locations. n Microsoft, IBM and SAP host the UDDI Business Registry. n Directory entry has three primary parts – the service provider, Web services offered, and bindings to the implementations. n Dynamically discovered Web services explicitly announce their arrival and departure from the network. 16

Agreement Coordination and Enumeration n n When multiple Web services complete a joint unit of work or operate under a common behavior, there must be common agreement on what protocols to use. This minimum amount of coordination among Web services is unavoidable. The specifications that define this functionality are WS-Reliable. Messaging, Reliable Messaging WS-Coordination, WSAtomic. Transaction and WS-Business. Activity. n n Enumeration, in particular, is achieved though establishing a session between the data source and the requestor. Successive messages within the session transport the collection of elements being retrieved. They are based on WS-Enumeration, WS-Transfer, and WS-Eventing. 17

Security Challenges n n n Previously Security professionals tend to focus narrowly on protecting assets Modern security systems that intelligently manage and store user information and cross-reference it with enterprise access rules Presently Security professionals help to rapidly launch new business activities while protecting assets To maximize the reach of Web services, end-to-end security must be provided when intermediaries are not trusted by the communicating endpoints. Even though the security requirements for Web services are complex, no new security mechanisms were invented to satisfy the needs of SOAP-based messaging 18

High Availability Web Services Using Cluster n Administrators of large Web sites are faced with managing the growth in a 24 x 7 environment. n Networking strategies and services, and Server clustering n IP traffic destined for the virtual server is assigned to the server in the cluster that is best suited for that transaction n : Clustering of servers provides the following benefits Rapid response to unexpected growth Balanced multiple work-load Continuous application availability Investment protection 19

Future Vision and Challenges n Technology vendors plan to develop, market, and lend online Web services to fulfill virtually any business function. n Companies will be able to simply search a public directory of applications and download those that fit their needs. n Right now we have only tools and standards which are still not matured, but it’s needless to say that its time to learn and practice some web services development Challenges: n How will vendors provide end-to-end security? n Who is accountable when vendors fail to deliver promised services? n How will vendors guarantee availability and reliability? n How will vendors handle pricing? 20

References n 1. An Introduction to the Web Services Architecture and Its Specifications by Luis Felipe Cabrera, Christopher Kurt, Don Box n 2. Oncoming wave with Web Services - by Benny Alexander n 3. High Availability Web Services by Cisco Systems n 4. Web Foundation Overview by Cisco Systems n 5. The Web Services Promise by Cisco Systems n 7. Web Services Infrastructure by Phil Wainewright 21