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SQL Anywhere 12.0.1 » SQL Anywhere Server - Programming » HTTP web services » Accessing web services using web clients

 

Quick start to accessing a SQL Anywhere HTTP web server

This topic illustrates how to access a SQL Anywhere HTTP web server using two different types of client application — Python and C#. It does not illustrate SQL Anywhere web service application capabilities to a full extent. Many SQL Anywhere web service features are available that are beyond the scope of this topic.

The following tasks are performed:

  • Create a procedure that connects to a web service on an HTTP server.

  • Perform operations on the result set sent by the HTTP server.

You can develop SQL Anywhere web client applications that connect to any type of online web server, but this guide assumes that you have started a local SQL Anywhere HTTP server on port 8082 and want to connect to a web service named SampleXMLService, created with the following SQL statements:



CREATE SERVICE SampleXMLService
    TYPE 'XML'
    USER DBA
    AUTHORIZATION OFF
    AS CALL sp_echo2(:i, :f, :s);

CREATE PROCEDURE sp_echo2(i INTEGER, f NUMERIC(6,2), s LONG VARCHAR )
RESULT( ret_i INTEGER, ret_f NUMERIC(6,2), ret_s LONG VARCHAR )
BEGIN
    SELECT i, f, s;
END;

For more information about setting up an HTTP server, see Quick start to using SQL Anywhere as an HTTP web server.

 Access an XML web service using C# or Python
  1. Write code that accesses the SampleXMLService web service.

    • For C#, use the following code:



      using System;
      using System.Xml;
      
      public class WebClient
      {
          static void Main(string[] args)
          {
              XmlTextReader reader = new XmlTextReader(
                  "http://localhost:8082/SampleXMLService?i=5&f=3.14&s=hello");
              while (reader.Read())
              {
                  switch (reader.NodeType)
                  {
                      case XmlNodeType.Element:
                          if (reader.Name == "row")
                          {
                              Console.Write(reader.GetAttribute("ret_i") + " ");
                              Console.Write(reader.GetAttribute("ret_s") + " ");
                              Console.WriteLine(reader.GetAttribute("ret_f"));
                          }
                          break;
                  }
              }
              reader.Close();
          }
      }

      Save the code to a file named DocHandler.cs.

      To compile the program, run the following command at a command prompt:

      csc /out:DocHandler.exe DocHandler.cs
    • For Python, use the following code:



      import xml.sax
      
      class DocHandler( xml.sax.ContentHandler ):
          def startElement( self, name, attrs ):
              if name == 'row':
                  table_int = attrs.getValue( 'ret_i' )
                  table_string = attrs.getValue( 'ret_s' )
                  table_numeric = attrs.getValue( 'ret_f' )
                  print('%s %s %s' % ( table_int, table_string, table_numeric ))
      
      parser = xml.sax.make_parser()
      parser.setContentHandler( DocHandler() )
      parser.parse('http://localhost:8082/SampleXMLService?i=5&f=3.14&s=hello')

      Save the code to a file named DocHandler.py.

  2. Run the application.

    • For C#, run the following command:

      DocHandler
    • For Python, run the following command:

      python DocHandler.py

The application displays the following output:

5 hello 3.14
 See also