Reading XML file

C# Code Example

This C# program continuously reads an XML file from a device located at http://192.168.0.60/status.xml and prints the values of specific XML nodes ( this means the measured values ).

 
using System;
using System.Threading.Tasks;
using System.Xml;

namespace xml_file_read
{
    internal class Program
    {
        private static string DeviceUrl = "http://192.168.0.60/status.xml";  //your IP address here
        static async Task Main(string[] args)
        {
            while (true)
            {
                try
                {
                    XmlTextReader reader = new XmlTextReader(Program.DeviceUrl);
                    XmlDocument xmlDoc = new XmlDocument();

                    xmlDoc.Load(reader);

                    XmlNodeList nodesV1 = xmlDoc.GetElementsByTagName("v1");
                    XmlNodeList nodesV2 = xmlDoc.GetElementsByTagName("v2");
                    XmlNodeList nodesV3 = xmlDoc.GetElementsByTagName("v3");

                    if (nodesV1.Count > 0)
                    {
                        Console.WriteLine($"v1: {nodesV1.Item(0).InnerText} V");
                    }

                    if (nodesV2.Count > 0)
                    {
                        Console.WriteLine($"v2: {nodesV2.Item(0).InnerText} V");
                    }

                    if (nodesV3.Count > 0)
                    {
                        Console.WriteLine($"v3: {nodesV3.Item(0).InnerText} V");
                    }

                    Console.WriteLine($"------------");

                    reader.Close();
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"An error occurred: {ex.Message}");
                }

                // Wait for 5 seconds before the next iteration
                await Task.Delay(1000);
            }
        }
    }
}
                        

Commentary

Here is a detailed comment on the functionality of the code :

• Namespace Imports: The program imports several namespaces:
  • System: Provides basic system functionality.
  • System.Threading.Tasks: Provides classes for asynchronous programming.
  • System.Xml: Provides classes for XML processing.
• URL Declaration:

  The program declares a static string DeviceUrl which holds the URL of the XML file to be read.

• Infinite Loop:

  The program enters an infinite loop to continually read data from the XML file.

• XML Reading and Parsing:

  Within the loop, the program performs the following steps:

  • XmlTextReader reader = new XmlTextReader(Program.DeviceUrl);: Creates an XmlTextReader to read from the URL.
  • XmlDocument xmlDoc = new XmlDocument();: Creates an XmlDocument object.
  • xmlDoc.Load(reader);: Loads the XML document from the reader.
  • XmlNodeList nodesV1 = xmlDoc.GetElementsByTagName("v1");: Retrieves nodes named "v1".
  • XmlNodeList nodesV2 = xmlDoc.GetElementsByTagName("v2");: Retrieves nodes named "v2".
  • XmlNodeList nodesV3 = xmlDoc.GetElementsByTagName("v3");: Retrieves nodes named "v3".
  • Conditional statements to print the inner text of the nodes if they exist.
  • reader.Close();: Closes the reader after processing.
• Exception Handling:

  The program includes a try-catch block to handle any exceptions that may occur during the XML reading and parsing process. If an exception occurs, it prints an error message.

• Delay Between Iterations:

  The program uses await Task.Delay(1000); to wait for 1 second before the next iteration of the loop.