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SQL Anywhere 11.0.0 » SQL Anywhere Server - Programming » SQL Anywhere Data Access APIs » SQL Anywhere web services


Tutorial: Accessing web services from Microsoft .NET

The following tutorial demonstrates how to access web services from Microsoft .NET using Visual C#.

To create SOAP and DISH services

  1. Copy the SQL Anywhere sample database from samples-dir to another location, such as c:\webserver\demo.db.

  2. At a command prompt, execute the following statement to start a personal web server. The -xs http(port=80) option tells the database server to accept HTTP requests on port 80. If you already have a web server running on port 80, use another port number such as 8080 for this tutorial.

    dbeng11 -xs http(port=80) c:\webserver\demo.db
  3. Start Interactive SQL. Connect to the SQL Anywhere sample database as the DBA. Execute the following statements:

    1. Define a SOAP service that lists the Employees table.
      CREATE SERVICE "SASoapTest/EmployeeList"
      TYPE 'SOAP'
      USER DBA
      AS SELECT * FROM Employees;

      Because authorization has been turned off, anyone can use this service without supplying a user name and password. The commands run under user DBA. This arrangement is simple, but insecure.

    2. Create a DISH service to act as a proxy for the SOAP service and to generate the WSDL document.
      TYPE 'DISH'
      GROUP "SASoapTest"
      USER DBA;

      The SOAP and DISH service must be of format DNET. In this example, the FORMAT clause was omitted when the SOAP service was created. As a result, the SOAP service inherits the DNET format from the DISH service.

  4. Start Microsoft Visual Studio. Note that this example uses functions from the .NET Framework 2.0.

    1. Create a new Windows application project using Visual C#.

      An empty form appears.

    2. From the Project menu, choose Add Web Reference.
    3. In the URL field of the Add Web Reference page, enter the following URL: http://localhost:80/demo/SASoapTest_DNET.
    4. Click Go.

      You are presented with a list of the methods available for SASoapTest_DNET. You should see the EmployeeList method.

    5. Click Add Reference to finish.

      The Solution Explorer window shows the new web reference.

    6. Add a ListBox and a Button to the form as shown in the following diagram.
      SOAP demonstration form.
    7. Rename the button text to Employee List.
    8. Double-click the Employee List button and add the following code for the button click event.
      int sqlCode;
      localhost.SASoapTest_DNET proxy = new localhost.SASoapTest_DNET();
      DataSet results = proxy.EmployeeList(out sqlCode);
      DataTableReader dr = results.CreateDataReader();
      while (dr.Read())
        for (int i = 0; i < dr.FieldCount; i++)
          string columnName = dr.GetName(i);
            string value = dr.GetString(i);
            listBox1.Items.Add(columnName + "=" + value);
          catch ( InvalidCastException )
            listBox1.Items.Add(columnName + "=(null)");
    9. Build and run the program.

      The listbox will display the EmployeeList result set as column name=value pairs.

      A try/catch block is included to handle NULL column values such as those found in the TerminationDate column of the Employees table.