Introduction to Web Services What is a Web Service? Characteristics of Web services. Why Web Services? Web Service Architecture. WSDL

What is a Web Service? Definitions: A Web service is a piece of business logic, located somewhere on the internet, that is accessible through standard internet protocols such as HTTP or SMTP. A Web service is a software application, accessible on the Web through a URL, that is accessed by clients using XML-based protocols, such as SOAP sent over accepted Internet protocols, such as HTTP.

Web Service Characteristics XML-based By using XML as the data representation layer for all web services protocols eliminates any networking, operating system or platform binding that a protocol has. Loosely coupled A consumer of a web service is not technology dependent and hence not tied to that web service directly. Adopting a loosely coupled architecture tends to make software system more manageable and allows simpler integration between different systems.

Web Service Characteristics Ability to be synchronous or asynchronous Asynchronous clients retrieve their result at a later point in time, while synchronous clients receive their result when the service is completed. Asynchronous capability is a key factor in enabling loosely coupled systems. Coarse-grained Web services technology provides a natural way of defining coarse-grained services that access the right amount of business logic.

Why Web Services? Many types of information available across the globe with Different data formats Different platforms Different networks Documents Product Data Spreadsheets

Why Web Services? – An Example Provide a full holiday shopping experience to customers with integrated business partners Flight Reservation Cruise Reservation Single Integrated Travel Web Site Hotel Reservation

Web Service Integration Connect (HTTP or SMTP) Find (UDDI) Define (WSDL) Transact (SOAP)

Each web service is made up of two parts: Service Each web service is made up of two parts: Service The implementation for a web service. It can be any application. The key requirement is that it be on a network-accessible platform, provided by the web service provider. Also it be accessible using SOAP. Service description The interface for a web service. It is expressed in XML (WSDL). This description includes the datatypes, operations, protocol bindings and network location for the web service’s implementation.

General Web Service Architecture Business Logic Listener (Servlet) Business Facade WebServer/App Server XML Request XML Response

Web Service Architecture (One Way)

Web Service Architecture (Another Way)