Consuming .NET Web Service from Java

• How to create a web service using .NET with C#.
• How to use DAL (Data Access Layer) to access database. This is used from Web Service code. So that Web Service doesn't depend on data access API.
• How to use custom classes in Web Services. This class goes to client in the form of XML Schema so that client can generate class from schema.
• How to consume this web service (created in .NET) from Java. We create proxy for this Web Service in Java and call methods through proxy.

Creating a web service

1. Start Visual studio.NET 2008/2005
2. Select File->New->Website. Select ASP.NET Web service as the type of the project and enter InventoryWS as the name of the project. Visual Studio provides Service.cs and Service.asmx files along with others. Delete these two files.
3. We add a new web service to the project using Website -> Add new item -> Web Service and enter name as InventoryService. Visual Studio creates InventoryService.aspx in root directory and InventoryService.cs in App_Code directory.

Creating Data Access Layer

I am using PRODUCTS table, which is created by me in MSDB database of Sql Server Express Edition. You have to do the same in your system. Create PRODUCTS table with the following structure.

PRODID    - int  (Primary key)
prodname  - varchar(50)
price     - money
qoh       - int
remarks   - varchar(200)
catcode   - varchar(10)

Add a class to the project using Website-> Add New Item -> Class and enter name as Product. Here is the code for Product.cs.

using System;
using System.Web.Services;
using System.Runtime.Serialization;

public class Product
{
    private int prodid, qty;    
    private string name, remarks;
    private double price;

    public int Qty
    {
        get { return qty; }
        set { qty = value; }
    }

    public int Prodid
    {
        get { return prodid; }
        set { prodid = value; }
    }

    public string Remarks
    {
        get { return remarks; }
        set { remarks = value; }
    }
    public string Name
    {
        get { return name; }
        set { name = value; }
    }

    public double Price
    {
        get { return price; }
        set { price = value; }
    }
}

  <connectionStrings>
    <add  name="msdbcs"  connectionString="data source=localhost\sqlexpress;integrated security=true;Initial Catalog=msdb"
              providerName="System.Data.SqlClient" />
  </connectionStrings >

using System.Web.Configuration;
public class Database
{
    public static string ConnectionString
    {
        get
        {
            return WebConfigurationManager.ConnectionStrings["msdbcs"].ConnectionString;
        }
    }
}

using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.Generic;
public class ProductsDAL
{
    public static List GetAllProducts()
    {
        SqlConnection con = new SqlConnection(Database.ConnectionString);
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from products", con);
        SqlDataReader dr = cmd.ExecuteReader();
        List products = new List();
        while (dr.Read())
        {
            Product p = new Product();
            p.Prodid = (int)dr["prodid"];
            p.Name = dr["prodname"].ToString();
            p.Remarks = dr["remarks"].ToString();
            p.Qty = (int)dr["qoh"];
            p.Price = Convert.ToDouble(dr["price"]);
            products.Add(p);
        }
        dr.Close();
        con.Close();
        return products;
    }

    public static Product GetProduct(int prodid)
    {
        SqlConnection con = new SqlConnection(Database.ConnectionString);
        con.Open();
        SqlCommand  cmd = new SqlCommand("select * from products where prodid = @prodid", con);
        cmd.Parameters.AddWithValue("@prodid", prodid);
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            Product p = new Product();
            p.Prodid = (int) dr["prodid"];
            p.Name = dr["prodname"].ToString();
            p.Remarks = dr["remarks"].ToString();
            p.Qty = (int) dr["qoh"];
            p.Price =  Convert.ToDouble (dr["price"]);
            return p;

        }
        else  // product not found
            return null;
    }
}

Using DAL in Web Service

Write the following code in InventoryService.cs.

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

[WebService(Namespace = "http://www.srikanthtechnologies.com/")] 
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class InventoryService : System.Web.Services.WebService {

    [WebMethod( Description ="Returns Details Of All Products")]
    public List GetAllProducts()
    {
        return ProductsDAL.GetAllProducts();
    }

    [WebMethod(Description = "Returns Details Of A Single Product")]
    public Product GetProduct(int prodid)
    {
        return ProductsDAL.GetProduct(prodid);
    }

}

From the page displayed in browser, click on methods and invoke them to test them.

Custom classes and WSDL

<s:complexType name="ArrayOfProduct">
  <s:sequence>
    <s:element minOccurs="0" maxOccurs="unbounded" name="Product" nillable="true" type="tns:Product" /> 
  </s:sequence>
</s:complexType>
<s:complexType name="Product">
   <s:sequence>
    <s:element minOccurs="1" maxOccurs="1" name="Qty" type="s:int" /> 
    <s:element minOccurs="1" maxOccurs="1" name="Prodid" type="s:int" /> 
    <s:element minOccurs="0" maxOccurs="1" name="Remarks" type="s:string" /> 
    <s:element minOccurs="0" maxOccurs="1" name="Name" type="s:string" /> 
    <s:element minOccurs="1" maxOccurs="1" name="Price" type="s:double" /> 
   </s:sequence>
</s:complexType>

Creating Proxy in Java

1. Start NetBeans IDE 6.5.
2. Select File->New Project. Select Java in category and Java Application in projects. Click on Next.
3. Enter InventoryClient as the name of the application. Change name of the class in Create Main Class option to Client
4. Click on Finish.
5. Select InventoryClient project in Projects window. Right click to invoke context menu. Select New->Other. Select Web service in categories and Web Service Client in File Types.
6. In the next window, select WSDL URL radio button (as shown below) and enter the URL at which InventoryService is running. Click on Finish. NetBeans creates required classes to access web service.

   

Write code in Java to call web service

1. Open Client.java
2. Go into main function and click on right button. From context menu select Web Service Client Resources -> Call Web Service Operation...
3. A window pops up with operations in the web service (shown below).

   

   Select GetProduct in InventoryServiceSoap12 section. NetBeans automatically writes code for you. Just assign product id 100 to prodid and change code regarding output, to complete the code.

      try { 
              // Call Web Service Operation
               com.srikanthtechnologies.InventoryService service = new com.srikanthtechnologies.InventoryService();
               com.srikanthtechnologies.InventoryServiceSoap port = service.getInventoryServiceSoap12();
               // TODO initialize WS operation arguments here
               int prodid = 100;
               // TODO process result here
               com.srikanthtechnologies.Product result = port.getProduct(prodid);
               System.out.println( result.getName());
           } catch (Exception ex) {
               // TODO handle custom exceptions here
           }
   

   Lines in bold are modified by me. The rest is provided by NetBeans. That's all you have to do to call web service created in .NET from Java.

   As you can see, NetBeans created a class Product for which information is provided in WSDL.

   Follow the same steps to call GetAllProducts method. Change the code as follows.

   try { // Call Web Service Operation
               com.srikanthtechnologies.InventoryService service = new com.srikanthtechnologies.InventoryService();
               com.srikanthtechnologies.InventoryServiceSoap port = service.getInventoryServiceSoap12();
               // TODO process result here
               com.srikanthtechnologies.ArrayOfProduct result = port.getAllProducts();
   
               List products = result.getProduct(); 
      
               for(Product p : products) {
                   System.out.println( p.getName() + " : "  + p.getPrice());
               }
   
               
           } catch (Exception ex) {
               // TODO handle custom exceptions here
           }
   

4. Now, run Client.java to get details of products from Java program.