A New Computing Paradigm

Overview of Web Services Over 66 percent of respondents to a 2001 InfoWorld magazine poll agreed that "Web services are likely to emerge as the next business model of the Internet." Over 66 percent of respondents to a 2001 InfoWorld magazine poll agreed that "Web services are likely to emerge as the next business model of the Internet."

Overview of Web Services Going to discuss Going to discuss What are Web services? What are Web services? How do they differ from previous computing and e-business models? How do they differ from previous computing and e-business models? Web services technologies Web services technologies Web services functions Web services functions

What are Web Services Web services are software programs that use XML to exchange information with other software via common Internet protocols Web services are software programs that use XML to exchange information with other software via common Internet protocols The emergence of the WWW and XML has increased the possibility for interoperable system-to-system communications The emergence of the WWW and XML has increased the possibility for interoperable system-to-system communications open standards for data exchange open standards for data exchange Use methods and properties Use methods and properties Object-oriented structure Object-oriented structure

What are Web Services Use HTTP as the key protocol of WWW Use HTTP as the key protocol of WWW A Web service can perform almost any kind of task. A Web service can perform almost any kind of task. Financial business Financial business Travel Travel Education Education customer-relationship-management (CRM) customer-relationship-management (CRM) Etc. Etc.

What are Web Services Differ from other computing models Differ from other computing models Web services are programmable Web services are programmable the service processes that information from an application and, if required, returns something to the application the service processes that information from an application and, if required, returns something to the application Based on XML Based on XML As an open, text-based standard As an open, text-based standard Enables Web services to communicate with other applications in different programming languages and run on different platforms Enables Web services to communicate with other applications in different programming languages and run on different platforms

What are Web Services Web services also are self-describing Web services also are self-describing They are accompanied by information explaining They are accompanied by information explaining How applications can access and use them How applications can access and use them Description is written in WSDL Description is written in WSDL Web services are discoverable Web services are discoverable Allow applications and developers to search for and locate desired Web services Allow applications and developers to search for and locate desired Web services

Additional Web Tool or New Distributed Computing Environment? The concepts behind Web services are complex The concepts behind Web services are complex Different people have different view because of different uses of Web services Different people have different view because of different uses of Web services

As a New Web Tool Program view Program view Web-based applications are programs Web-based applications are programs create Web content- including HTML, images and other material - for Web browser clients create Web content- including HTML, images and other material - for Web browser clients Like many distributed applications Like many distributed applications Web application are built on a multi-tier (n-tier) architecture; Web application are built on a multi-tier (n-tier) architecture; this means that the application's functionality is divided into separate, logical groupings this means that the application's functionality is divided into separate, logical groupings

As a New Web Tool It has been difficult to find an effective method of integrating Web-based applications (communication between applications) It has been difficult to find an effective method of integrating Web-based applications (communication between applications) interacting with another's client tier before Web services interacting with another's client tier before Web services From HTML markup of clients ’ applications From HTML markup of clients ’ applications Not efficient Not efficient Prone to errors Prone to errors

As a New Web Tool Actually, direct communication between applications' middle tiers without employing Web services is possible Actually, direct communication between applications' middle tiers without employing Web services is possible Need IT helps for techniques Need IT helps for techniques Costly to employ and maintain Costly to employ and maintain Not for general connections Not for general connections Security problems Security problems

As a New Web Tool Web services solve this Web services solve this provide a standard method for enabling communication between applications ’ middle tiers over a network. provide a standard method for enabling communication between applications ’ middle tiers over a network. Use XML for general purposes of data applications and integration Use XML for general purposes of data applications and integration

Benefits of Web Services over Other Distributed Computing Technologies There is nothing special about Web services. There is nothing special about Web services. From a purely technical perspective, there is "nothing special" about Web services From a purely technical perspective, there is "nothing special" about Web services However, most of old technologies have a downside However, most of old technologies have a downside overly complex overly complex prone to errors prone to errors do not work well across firewalls do not work well across firewalls not scalable enough to support use over a large distributed network like the Internet not scalable enough to support use over a large distributed network like the Internet most are in some manner specific to the vendor or platform for which they were designed most are in some manner specific to the vendor or platform for which they were designed none offers true interoperability none offers true interoperability

Benefits of Web Services over Other Distributed Computing Technologies Web services will change the world Web services will change the world The infrastructure of Web services solves many problems inherent in previous distributed computing technologies The infrastructure of Web services solves many problems inherent in previous distributed computing technologies this is the reason why Benfield believes they "will change the world." this is the reason why Benfield believes they "will change the world." Internet is ubiquitous today, and Web services function over HTTP Internet is ubiquitous today, and Web services function over HTTP companies can expose and access Web services using technology that they already have in place. companies can expose and access Web services using technology that they already have in place. Web services is that they are more interoperable Web services is that they are more interoperable Use an open, text-based standard XML to communicate among systems. Use an open, text-based standard XML to communicate among systems. Nearly all major software vendors have agreed to use the same core standards to enable Web services: SOAP, WSDL and UDDI Nearly all major software vendors have agreed to use the same core standards to enable Web services: SOAP, WSDL and UDDI

Benefits of Web Services over Other Distributed Computing Technologies Web services could vastly improve collaborative software development Web services could vastly improve collaborative software development developers can write code in the programming languages with which they are most comfortable under Web services, developers can write code in the programming languages with which they are most comfortable under Web services, Then merge their work with that of other developers writing in other languages for different platforms. Then merge their work with that of other developers writing in other languages for different platforms. Reduce the efforts to learn new languages Reduce the efforts to learn new languages

Benefits of Web Services over Other Distributed Computing Technologies Emergence of more modular applications Emergence of more modular applications Modular programs are less prone to errors and enable programmers to reuse components Modular programs are less prone to errors and enable programmers to reuse components Widespread adoption of Web services to increase modular programs Widespread adoption of Web services to increase modular programs Object-oriented concepts Object-oriented concepts

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Why is this so special? many Web sites enable users to perform functions similar to those Why is this so special? many Web sites enable users to perform functions similar to those It is the technologies behind these capabilities that are innovative It is the technologies behind these capabilities that are innovative unlike Web sites, Web services are designed to be accessed and employed by other applications unlike Web sites, Web services are designed to be accessed and employed by other applications

Key Web Services Technologies The use of XML and XML-based standards-most commonly SOAP, WSDL and UDDI The use of XML and XML-based standards-most commonly SOAP, WSDL and UDDI SOAP provides a communication mechanism between services and applications SOAP provides a communication mechanism between services and applications WSDL offers a uniform method of describing services to other programs WSDL offers a uniform method of describing services to other programs UDDI enables the creation of searchable Web services registries UDDI enables the creation of searchable Web services registries Independent of specific programming languages, operating systems and hardware plat- forms Independent of specific programming languages, operating systems and hardware plat- forms

Role of Various Standards

XML (Extensible Markup Language) XML XML Developed from the Standard Generalized Markup Language (SGML) Developed from the Standard Generalized Markup Language (SGML) XML is a widely accepted standard for describing data and creating markup languages XML is a widely accepted standard for describing data and creating markup languages XML was defined by the W3C as an open, standard technology XML was defined by the W3C as an open, standard technology Data independence, or the separation of content from its presentation Data independence, or the separation of content from its presentation XML documents contain data, but no formatting instructions, XML documents contain data, but no formatting instructions, so applications that process XML documents must decide how to display the documents' data. so applications that process XML documents must decide how to display the documents' data. An XML parser is a software program that checks an XML document's syntax and makes the XML document's data available to applications An XML parser is a software program that checks an XML document's syntax and makes the XML document's data available to applications

SOAP (Simple Object Access Protocol) One of the most common standards used to deliver Web services One of the most common standards used to deliver Web services Enable data transfer between systems distributed over a network Enable data transfer between systems distributed over a network SOAP messages are the most common means through which the two systems exchange data SOAP messages are the most common means through which the two systems exchange data A SOAP message sent to a Web service invokes a method provided by the service A SOAP message sent to a Web service invokes a method provided by the service The service then uses information contained in the SOAP message to perform its function The service then uses information contained in the SOAP message to perform its function A SOAP message consists of three main parts: an envelope, a header and a body A SOAP message consists of three main parts: an envelope, a header and a body SOAP basically consists of a set of standardized XML Schemas SOAP basically consists of a set of standardized XML Schemas

WSDL (Web Services Description Language) Web services are self-describing Web services are self-describing every Web service is accompanied by information that enables developers to employ the service every Web service is accompanied by information that enables developers to employ the service These descriptions typically are written in WSDL These descriptions typically are written in WSDL WSDL WSDL an XML-based language an XML-based language through which a Web service can convey to other applications the methods that the service provides and how those methods can be accessed through which a Web service can convey to other applications the methods that the service provides and how those methods can be accessed

WSDL WSDL is a language meant to be read by applications, rather than by humans WSDL is a language meant to be read by applications, rather than by humans The WSDL specification emerged when vendors Microsoft and IBM decided to combine their description technologies into a universal standard. The WSDL specification emerged when vendors Microsoft and IBM decided to combine their description technologies into a universal standard. A WSDL document defines the kinds of messages a Web service can send and receive A WSDL document defines the kinds of messages a Web service can send and receive specifying the data that a calling application must provide for the Web service to perform its task specifying the data that a calling application must provide for the Web service to perform its task

UDDI (Universal Description, Discovery and Integration) Enables developers and businesses to publish and locate Web services on a network Enables developers and businesses to publish and locate Web services on a network Originally designed by Microsoft, IBM and Ariba Originally designed by Microsoft, IBM and Ariba share information about their businesses and business processes with potential partners and affiliates share information about their businesses and business processes with potential partners and affiliates Allows companies to describe their own services and electronic processes, discover those of other companies and integrate others' services into their systems. Allows companies to describe their own services and electronic processes, discover those of other companies and integrate others' services into their systems.

UDDI Defines an XML-based format Defines an XML-based format in which companies can describe their electronic capabilities and business processes; in which companies can describe their electronic capabilities and business processes; the specification also provides a standardized method of registering and locating the descriptions on a network, such as the Internet the specification also provides a standardized method of registering and locating the descriptions on a network, such as the Internet A UDDI registry's structure is conceptually similar to that of a phone book A UDDI registry's structure is conceptually similar to that of a phone book

UDDI Companies can store their information either Companies can store their information either in private UDDI registries in private UDDI registries which are accessible only to approved business partners which are accessible only to approved business partners in public UDDI registries in public UDDI registries which any interested party can use which any interested party can use The largest, most comprehensive public UDDI registry is the UDDI Business Registry (UBR) The largest, most comprehensive public UDDI registry is the UDDI Business Registry (UBR) developed to facilitate the formation of new business relationships developed to facilitate the formation of new business relationships