sexta-feira, 27 de março de 2015

C# Web Service

After the last post on PHP web service now we develop a web service with Visual Studio 2013 in C#.

Let's start by creating a ASP.NET project.




In the next screen wee choose an Empty application.

Now in we add a new item to our project.


And next choose Web Service


By now the Visual Studio have created the basic structure of our web service with one method called HelloWorld as an example.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;

namespace WebApplication2
{
    /// <summary>
    /// Summary description for WebService1
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
    // [System.Web.Script.Services.ScriptService]
    public class WebService1 : System.Web.Services.WebService
    {

        [WebMethod]
        public string HelloWorld()
        {
            return "Hello World";
        }
    }
}

In this post were going to create a new method call listUsers that will receive one parameter indicating the type of output to be generated, XML or JSON.

        [WebMethod]
        public string listUsers(string op)
        {
            if(op=="json"||op=="JSON")
                return devolveRegistosJSON();

            return devolveRegistosXML();
        }

As is easy to see in the code there are two function that get called, one return a JSON string and the other a XML string. Let's look at that code.

Starting with de JSON.

        public string devolveRegistosJSON()
        {
            var jsonSerializer = new System.Web.Script.Serialization.JavaScriptSerializer();
            string registos = "";
            string strligacao = "Database=database;Server=server;UID=user;PWD=password;";
            MySqlConnection ligacao = new MySqlConnection(strligacao);
            ligacao.Open();
            string strSQL = "SELECT * FROM test_users;";
            MySqlCommand comando = new MySqlCommand(strSQL, ligacao);
            MySqlDataReader dados = comando.ExecuteReader();
            List<Registo> lDados = new List<Registo>();
            while (dados.Read())
            {
                lDados.Add(new Registo(int.Parse(dados[0].ToString()), dados[1].ToString(), dados[2].ToString()));
            }
            registos = jsonSerializer.Serialize(lDados);
            lDados.Clear();
            dados.Dispose();
            comando.Dispose();
            ligacao.Close();
            ligacao.Dispose();
            return registos;
        }

This functions uses a serializer to generate the JSON string from a list of objects with the data.
Each object is an instance of the class Registo.

        [Serializable]
        public class Registo
        {
            public int id { get; set; }
            public string name { get; set; }
            public string country { get; set; }
            public Registo(int id, string name, string country)
            {
                this.id = id;
                this.name = name;
                this.country = country;
            }
        }

Next the XML version.

public string devolveRegistosXML()
        {
            string registos = "";
            string strligacao = "Database=database;Server=server;UID=user;PWD=password;";
            MySqlConnection ligacao = new MySqlConnection(strligacao);
            ligacao.Open();
            string strSQL="SELECT * FROM test_users;";
            MySqlCommand comando = new MySqlCommand(strSQL,ligacao);
            MySqlDataReader dados = comando.ExecuteReader();
            while (dados.Read())
            {
                string registo = "";
                registo=adicionarTag("id", dados[0].ToString());
                registo += adicionarTag("name", dados[1].ToString());
                registo += adicionarTag("country", dados[2].ToString());
                registos += adicionarTag("registo", registo);
            }
            registos = adicionarTag("registos", registos);
            dados.Dispose();
            comando.Dispose();
            ligacao.Close();
            ligacao.Dispose();
            return registos;
        }

This functions makes use of a helper function to generate the xml tags.

        public string adicionarTag(string tag, string texto)
        {
            string temp = "<" + tag + ">" + texto + "</" + tag + ">";
            return temp;
        }

When testing the service this is the page presented.


If we choose the new method the browser shows us a form with a field for the parameter of the service.

By choosing XML we get.
If the choice is JSON.
Get the project here.

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