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Introduction to Web Services—Topics

Introduction to Web Services—Topics. Creating a Web Service Testing Web Services Referencing a Web Service in a Visual Studio Project Support for Web Services Solutions in Visual Studio. Creating a Web Service. Create a new VS project of type “ASP.Net Web Service”

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Introduction to Web Services—Topics

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  1. Introduction to Web Services—Topics • Creating a Web Service • Testing Web Services • Referencing a Web Service in a Visual Studio Project • Support for Web Services Solutions in Visual Studio

  2. Creating a Web Service • Create a new VS projectof type “ASP.Net WebService” • You automatically have“Service1.asmx” as thedefault service. • Rename this or delete it and add a new service giving it a meaningful name. • You may have many web service files in a single solution • Break them up by functionality

  3. Adding Code to the Web Service • Add whatever methods, properties, etc., that you need to your web service • Precede subroutines and functions that you want to expose to the web with the line:<WebMethod(Description:="Returns a hard-coded test string")> _ Public Function HelloWorld() As String Return "Hello World“ End Function • Procedures lacking this prefix will be used internally within the service Note Line Continuation Character

  4. Testing Web Services • Web services can be tested without a consumer application • Navigate to the services .asmx page • Select the public method you wish to test

  5. Testing Web Services (cont.) • The CalcTotalfunction requirestwo parameters • Test provides simpletext boxes for input • “Invoke” buttontests the service

  6. Testing Web Services (cont.) • The result screen shows the XML-encapsulated result of the web service method/function <WebMethod(Description:="Calculation example with two numeric inputs.")> _ Public Function CalcTotal(ByVal sglPrice As Single, _ ByVal intQty As Integer) As Single Return sglPrice * intQty * 1.06 End Function

  7. Testing Web Services (cont.) • You can also set the web services solution as the start up project in Visual Studio’s Solution Explorer • Running the solution brings up the test page

  8. Referencing a Web Service in a VB Project • The VB client project (both Windows and ASP.Net) must be ‘aware’ of the capabilities of a web service you want it to use • Available methods and properties • Data types of parameters and return values • This is done with a proxy class that contains this information

  9. Adding Web Reference • Right click project and select“Add Service Reference…”

  10. Adding Web Reference (cont.) • Click Advanced…

  11. Add Web Reference (cont.) • Click "Add Web Reference…"

  12. Adding Web Reference (cont.) • Find your web service in this solution

  13. Add a Web Reference (cont.) • Select the desired web service

  14. Creating a Web Reference (cont.) Click Add Reference Capabilities Name you will reference in code

  15. Special Note • It is very, very important that you complete the web service before you add the reference to it in another web or Windows project • The Web Reference freezes the interface of the web service at the time the reference was added to the project • I have had a great deal of difficulty getting these references to recognize changes to the interface • You can change coding within the web exposed functions and subs and other procedures with no problem

  16. Support for Web Services in Visual Studio • Web services providersand consumers are multiple independentprograms • Visual Studio lets you work with both in onesolution • Debug across programs • See code in both • Etc. • Set Startup Project

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