1. What is a web service?  A remote procedure call (RPC) over HTTP.  A web-accessible operation that takes input and returns results in XML.  Like a web page, but just the data with no presentation specifications.  Web definitions Web definitions

2. Importance of Web Services  Larry Page, on why Google introduced its search API: “Within a few years, there will be more programs (agents) accessing Google than people accessing Google.”

3. Without Web Services: Content and Presentation mixed Database Servlet html Data can only be viewed in forms provided by Server. Data left hidden in database. Scrapers not robust or ethical.

4. Web Services allow 3 rd parties to display data how ever they want Database Service Servlet AServlet CServlet B xml html

5. Examples  Bookstores Using Amazon API  If Google Scholar had a service, could develop graph view, etc.

6. Web Services Allow for Aggregators Database A Database BDatabase C Database D Service B Service A Service C Service D Aggregator Servlet html xml

7. Competing Web Service Standards  WSDL, SOAP, UDDI  REST  XML-RPC

8. WSDL, SOAP, UDDI  WSDL – Web Service Description Language  SOAP – Simple Object Access Protocol  UDDI – Universal Description, Discovery, and Integration

9. IDE Support Programmer writes class in favorite language Programmer marks as “web service” IDE generates wsdl file and soap service walla! Writing a Service Writing a Client Programmer provides uri of some web service IDE generates client stub Programmer makes calls to service methods.

10. XML is the plumbing Client Server JavaC# Generated SOAP Plumbing: programmers need not worry