Introduction to Web Services Introduction What is Web

Introduction to Web Services

Introduction Ø What is Web Services? l l l There is no concise definition yet Use Web to provide services Encompass a set of related standards that can enable any two computer applications to communicate and exchange data via the Internet. Provide a new tool for people to communicate with each other Ø Many factors indicate that Web services will radically change IT architectures and partner relationships. Ø l including software vendors' widespread support for underlying standards Introduction to Web Services

Computing Advancements and Web Services Ø 1960 s l l Ø many large software-development projects encountered severe difficulties. Development efforts typically ran behind schedule costs often greatly exceeded budgets the finished products were unreliable 1970 s l l l structured programming disciplines of structured systems analysis and design improved software technology did begin to appear Introduction to Web Services

Computing Advancements and Web Services Ø 1980 s and 1990 s l l Object-oriented programming became widely used improve the software-development process dramatically Introduction to Web Services

What are objects Object technology is a packaging scheme that enables programmers to create meaningful software units Ø Objects are focused on particular applications areas Ø l l E. g. date objects, time objects, paycheck objects, invoice objects, audio objects, video objects, file objects, record objects and so on Objects have • properties • perform actions (behaviors) l Classes represent groups of related objects Introduction to Web Services

Web Services and Languages Ø Procedural programming languages l l Ø Such as Fortran, Pascal, Basic and C Focused on actions (verbs) rather than objects (nouns) Do not mirror real-world entities effectively Not particularly reusable Object-oriented languages l l l Such as C++, Java, C# and Visual Basic. NET, Programmers can write code in an object- oriented manner that reflects the way in which they perceive the world Code reusable Group classes into class libraries Significant productivity gains Introduction to Web Services

Web Services and Languages Ø Web services take advantage of object- oriented programming techniques l l l Web services enable developers to build applications from existing software components Encourages a modular approach to programming Transforming a network such as the Internet into an enormous library of programmatic components available to developers Introduction to Web Services

Web Services and Distributed Computing Ø Distributed computing l l Different tasks to be performed on different computers, i. e. an organization' s computing is distributed over networks, instead of being performed only at a central computer installation • • l l OMG's Common Object Request Broker Architecture (CORBA) Microsoft's Distributed Component Object Model (DCOM) Sun Microsystem's Remote Method Invocation (RMJ) IBM's Distributed System Object Model (DSOM) more efficient, or even necessary N-tier applications often split up applications over numerous computers • For example, a three-tier application might have a user interface on one computer, business-logic processing on a second, and a database on a third-all interacting as the application runs Introduction to Web Services

Web Services and Distributed Computing l l Different computers throughout a network must be able to communicate Shortcomings • interoperability (the ability to communicate and share data with software from different vendors and platforms) is limited among these technologies • For example, DCOM and CORBA, cannot communicate easily • Such problems have impeded distributed computing ability to facilitate business-process integration and automation Introduction to Web Services

Web Services and Distributed Computing Ø Web services improve distributed computing capabilities by addressing the issue of limited interoperability l l Web services operate using open (i. e. , nonproprietary) standards Web services-based applications are often easier to debug, because Web services use text-based communication protocols Introduction to Web Services

World Wide Web (WWW) Ø Tim Berners-Lee of CERN (the European Organization for Nuclear Research) began to develop a technology for sharing information via hyperlink text documents l l Ø Invent the Hyper. Text Markup Language (HTML) Use Hypertext Transfer Protocol (HTTP) to form the backbone of his new hypertext information system World Wide Web Ubiquitous, platform independent technologies Introduction to Web Services

Web Services v. s. WWW Ø Web services make good uses of WWW l l l Web services can operate over Internet and Web protocols, such as HTTP Extend the Web's capabilities to include direct communication between computer programs Web Services is Ubiquitous, platform independent technologies Introduction to Web Services

Web Services v. s. Electronic Data Interchange (EDI) Ø Organizations have invested in Electronic Data Interchange (EDI) technology to link business partners and help manage supply chains Ø EDI messages are not standards l Need separate EDI connections among organizations Ø EDI systems are tightly coupled l Difficult to maintain Introduction to Web Services

Web Services v. s. Electronic Data Interchange (EDI) Ø Web services provide capabilities similar to those offered by EDI, but less expensive to implement l l l Fewer incompatibility problems arise because of open standards Web services is loosely coupled allows organizations to use two technologies together or to phase out EDI Introduction to Web Services

Emergence of Web Services Ø The good part l l l HP's product, e-Speak, and Microsoft’s Web services as a key component of its. NET initiative Microsoft announced Web services, it was clear that the technology could revolutionize distributed computing Both of them wish one of them would be a universal distributed-computing standard Introduction to Web Services

Emergence of Web Services Ø The bad part l l Different organizations had already made significant investments in distributedcomputing platforms Migration to a different platform is a big problem • costs businesses time • money and employee productivity Introduction to Web Services

Emergence of Web Services Ø However, l l l Most major software vendors have recognized that Web services technology represents a significant step forward for computing The main standard used in Web services is XML Use Simple Object Access Protocol (SOAP) based on XML • a messaging protocol for transporting information and instructions between Web services l Web Services Description Language (WSDL) and Universal Description is based on XML • WSDL - a standard method of describing Web services and their specific capabilities l Universal Description, Discovery and Integration (UDDI) is also based on XML • defines XML-based rules for building directories in which companies advertise themselves and their Web services Introduction to Web Services

Web Services Advantages Ø “Why is the computing industry so excited about Web services, given that many other promising technologies have failed? " l Web services operate using open, text-based standards • The most important part l Web services promote a modular approach to programming • Use OOP concept to increase reusability l Web services are comparatively easy and inexpensive to implement • Base on the current existing infrastructure l Web services can significantly reduce the costs of enterprise application integration (EAI) and business-to-business (B 2 B) communications • Reduce investments l Web services can be implemented incrementally, rather than all at once Introduction to Web Services

Introduction to Web Services

Real Web Services Ø Organizations are employing Web services to integrate and improve communications systems l Ø E. g. , the UC-Berkeley using Web services to unify the school's e-mail, voice mail and facsimile service into individual in-boxes that are accessible from cell phones, PDAs, telephones or e-mail clients. Manufacturing companies are implementing Web services to improve supply chains, inventory and customer-management systems. l Allow customers to access company’s information via Web Services Introduction to Web Services

Real Web Services Ø The consulting firm Accenture has developed Web services products, called Live Information Models, that enable stock traders to access real-time quotes and market information l Ø allows brokers to receive real-time updates and to access different information sources from a single terminal Airlines, travel agencies, rental-car companies and hotels all provide travel-related services l l Difficult to integrate because of different platforms or operation systems With Web services, companies in the travel business can streamline the reservation process Introduction to Web Services

Examples of existing Web Services and their capabilities Introduction to Web Services

Web Services Challenges Ø Significant challenges for application developers and IT staffs l SOAP, WSDL and UDDI – the standards that drive Web services – are still in draft form • • l l SOAP and WSDL are under development by the W 3 C UDDI has not yet been submitted to a standards organization Many businesses want to wait until the underlying technology are stable before adopting it Some are nervous that the current cooperation among software vendors might fail • E. g. , Microsoft, IBM and Sun to create interoperable implementations might fail • resulting in splinter standards • incompatible Web services implementations. Introduction to Web Services

Web Services Challenges Ø Companies refuse to release their intellectual property l Ø The lack of standard security procedures l l Ø Hard to make open standards SOAP, are not designed to provide security companies are hesitant to deploy Web services until security mechanisms are standardized Defining and guaranteeing Quality of Service (Qo. S) l l meet provider and consumers’ expectations Bad Qo. S, e. g. , slow response times, infrequent updates, an inability to handle large numbers of requests Introduction to Web Services