1. INFOSYS 290, Section 3, Fall 2005, Web Services: Concepts, Design and Implementation Adam Blum ablum@good.com Lecture 4: Creating Web Services

2. Today’s Content Creating Web Services Overview Demo Web Service Creation –Raw computation –Database –HTML scraping –XML wrapping –SOAP web service wrapping Break To Set Up Environments –MindReef SOAPScope –AboveAll –Visual Studio Redemo of Consuming Web Services – MindReef –AboveAll –Visual Studio Lecture: Asynchronous Web Services

3. Creating Web Services Create a web service project Design the interface –Demoing “method-oriented interfaces” today Place [WebMethod] around the exposed methods Write your internal logic Test with Visual Studio and debug

4. Example Web Services Demonstrating Various Techniques Raw computation –PokerOdds (http://www.sims.berkeley.edu/academics/courses/is290- 3/f05/samples/PokerOdds) Database creation –ProjectTraq –Workouts XML wrapping –Blogs (http://www.sims.berkeley.edu/academics/courses/is290- 3/f05/samples/PokerOdds) –SportsBetLines (http://www.sims.berkeley.edu/academics/courses/is290- 3/f05/samples/PokerOdds) HTML/HTTP scraping –PokerOdds AnalyzeHands() SOAP web service wrapping –SalesForce

5. Informational Web Services QCUD Multiple records in query Doesn’t have to have CUD Richly descriptive records Generally comes from a persisted store Contrast with computation or transactional web service

6. Informational Web Service Examples Sales accounts, contacts, tasks, opportunities Project bugs Helpdesk, customer support items Blog entries Newsfeeds

7. Consuming Web Services Ad hoc tools and management systems –E.g. MindReef SOAPScope Forms design environments –E.g. AboveAll Studio Third generation traditional programming environments –E.g. Visual Studio.NET 2005

8. Asynchronous Web Services

9. Why Asynchronous Web Services? Speed –Due to overhead of XML and http XML web services can be SLOW Unpredictability –Your app may be invoking a web service that itself is slow, unreliably available or involves a human in the process Size –Moving to larger coarsegrained documents and less frequent chatty method calls can introduce more overhead Blocking on downstream services creates instant bottlenecks in your application

10. Creating Asynchronous Web Services Write “begin” and “end” methods versus single invocation methods VisualStudio.NET generates: –public System.IAsyncResult BeginValidateEmailAddress(string emailAddress, System.AsyncCallback callback, object asyncState) { – return this.BeginInvoke("ValidateEmailAddress", new object[] {emailAddress}, callback, asyncState); –} –public CheckEmailResult EndValidateEmailAddress(System.IsyncResult asyncResult) { – object[] results = this.EndInvoke(asyncResult); – return ((CheckEmailResult)(results[0])); –}

11. Invoking Asynchronous Web Services Polling Blocking Callbacks

12. Polling // polling version private void Command1_Click(object sender, System.EventArgs e) { emailvalidatorproxy=new Einsteinware.EmailServices(); int start=DateTime.Now.Second; IAsyncResult ar=emailvalidatorproxy.BeginValidateEmailAddress(TextBox1.Text, null,null); while (!ar.IsCompleted){ –//do stuff } switch(emailvalidatorproxy.EndValidateEmailAddress(ar)){ –case Einsteinware.CheckEmailResult.Valid: Label1.Text="Valid"; break; –default: Label1.Text="Invalid"; break; }

13. Blocking private void Command1_Click(object sender, System.EventArgs e) { emailvalidatorproxy=new Einsteinware.EmailServices(); IAsyncResult ar=emailvalidatorproxy.BeginValidateEmailAddress(TextBox1. Text,cb,emailvalidatorproxy); // do lots of stuff ar.AsyncWaitHandle.WaitOne(); switch(response) { case Einsteinware.CheckEmailResult.Valid: Label1.Text="Valid"; break; default: Label1.Text="Invalid"; }

14. WaitHandle Object WaitOne –Waits for this one handle WaitAny –Static method which takes array of WaitHandles, returns when any have completed WaitAll –Returns when all have completed

15. Invoking with a Callback // callback version private void Command1_Click(object sender, System.EventArgs e) { emailvalidatorproxy=new Einsteinware.EmailServices(); // instantiate the AsyncCallback delegate AsyncCallback cb = new AsyncCallback(EmailvalidatorCallback); int start=DateTime.Now; IAsyncResult ar= emailvalidatorproxy.BeginValidateEmailAddress( TextBox1.Text,cb,null); Label1.Text=Label1.Text + "(" + System.Convert.ToString( DateTime.Now.CompareTo(start) ")"; }

16. The Callback Itself public delegate void MyDelegate(Label l,String s); private void EmailvalidatorCallback(System.IAsyncResult ar) { CheckEmailResult response=emailvalidatorproxy.EndValidateEmailAddress(ar); switch(response) { case CheckEmailResult.Valid: message="Valid"; break; … } responseLabel.Invoke( new MyDelegate(DisplayResponse),new object[]{label1,message}); } private void DisplayResponse(Label label,String message) { label.Text=message; Form1.ActiveForm.Refresh(); } Remember: callbacks are on a separate thread and need a way to communicate back to the main thread to display…hence delegates

17. Using the Async State Object // using async state to handle two label objects private void button1_Click(object sender, System.EventArgs e) { label1.Text="";label2.Text=""; emailvalidatorproxy=new Einsteinware.EmailServices(); IAsyncResult ar= emailvalidatorproxy.BeginValidateEmailAddress( textBox1.Text,new AsyncCallback(EmailvalidatorCallback),label1); IAsyncResult ar2= emailvalidatorproxy.BeginValidateEmailAddress( textBox1.Text,new AsyncCallback(EmailvalidatorCallback),label2); }

18. Callback Using the Async State Object private void EmailvalidatorCallback(System.IAsyncResult ar) { –CheckEmailResult response=emailvalidatorproxy.EndValidateEmailAddress(ar); –String message=""; –switch(response) –{ –case EinsteinwareCheckEmailResult.Valid: message="Valid“; break; –case CheckEmailResult.InvalidUser: message="Invalid user"; break; … –} –Label responseLabel = (Label)ar.AsyncState; –responseLabel.Invoke(new MyDelegate(DisplayResponse),new object[]{responseLabel,message}); }

19. Course Project Goal –Build “web service consuming” client applications from desktops and mobile devices Requirements –Use an “informational” web service Has QCUD (Query, Create, Update and Delete operations) Query returns MULTIPLE records –Consume web service from AboveAll or Visual Studio for desktop –Consume WS from GoodAccess Web Services or Visual Studio from mobile device –Optionally write or enhance a backend web service Possibly as a “proxy web service” layer on top of original web service Only if previous steps are achieved –Demo to class –Write up as three page paper including: architecture and UI design Team size –Two people per project Proposal –Due today, will accept later

20. References Specs –SOAP Specification, http://www.w3.org/TR/soap/ –WSDL Specification, http://www.w3.org/TR/wsdlhttp://www.w3.org/TR/wsdl –UDDI Specification, http://www.uddi.org/specification.html http://www.uddi.org/specification.html Tools –Visual Studio, http://microsoft.com/vstudiohttp://microsoft.com/vstudio –Microsoft Web Services Enhancements http://msdn.microsoft.com/webservices/building/wse/default.aspx

21. How To Reach Me ablum@good.com 408-396-5490 Office hours Thursday at 4pm web-services@sims.berkeley.edu