Consuming ASMX Services In Xamarin Forms

Fabio Silva Lima

Xamarin.FormsConsumming ASMX Services

7 Comments

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Munson Chien5y ago
Hi, I download the zip file and open in VS 2019 Pro. But the asmx project can't be open. How do I sort it out? Thanks.
Eduardo Lima6y ago
_customerSoapService = DependencyService.Get<ICustomerSoapService> this line of returns empty I don't know why
yuvika gupta7y ago
My app keeps crashing not always but sometimes with error "app stopped unexpectedly" . Could it because of memory, as restarting the Android device works. Is there a way I can clear the memory after call of Asyn Web service. I have scanning products app and for each item scan it calls web service to remove item from the list once scanned. Any help is appreciated.
Phang Tingya7y ago
Hi, I encounter error with the "CustomerSoapService" in Xamarin.Droid project. This line "return new List<ICustomer>(result); " returns Error CS1503 Argument 1: cannot convert from 'IMSr2.Droid.IMSWS.Project[]' to 'int'. Appreciate if you could help on this.
yuvika gupta8y ago
Hello, How to return errors along with list of customers
Ganesh Vadlakonda9y ago
Hi, It looks good, But I have bit confusion about CustomersWs.Customers service; Can you please elaborate bit clearly about it, like how to add WebReference to the .Droid and .iOS projects.
- Fabio Silva Lima9y ago
  Hi Ganesh Vadlakonda how are you doing? Have you downloaded source code from my github repository? You must add web reference in your Droid or iOS project like any other project. Right button in Droid project, choose Add, and Web Reference. Put the wsdl URL for CustomersWS http://localhost/FSL.WS/Customers.asmx?wsdl. Do same thing on iOS project. It will create a proxy class for all methods and parameters for that Customers.asmx webservice for you to use. Please contact me in facebook or linkedin social networks. Thank you.

When I started working with Xamarin forms, one of the first things I required was consuming services. When you use Xamarin forms, consuming RestFull API Services is quite easy (I will post about that later) but ASMX Services will need some additional implementation for different platforms.

First of all, I have created a cross-platform Xamarin forms portable project, using Visual Studio 2015. For the blog, I don't use any third party component to manage the Services. I do like to create my own implementation for understanding purposes.

Ok, let's get started.

What do we need?

An interface for the Service with all the methods which we want. It will be at portable project.
The Service Web Reference. This references the service in both Xamarin.iOS and Xamarin.Droid projects.
A class that implements the interface created above. This class will be a wrapper for the Service itself. It must be in both Xamarin.Droid and Xamarin.iOS projects. Thus, you will need to create two classes.
Add Xamarin forms dependency (dependency injection) for that interface in both Xamarin.Droid and Xamarin.iOS projects.
A static property in the app, which is a portable project to consume the Service. This property will be "injected" by Xamarin forms.

OK, stop. How does that thing will work? Let's get the Android implementation.

Let's say you have a view and you want to get all the customers from your ASMX Service. You have a method that receives a criteria filter and returns a list of the customers.

First, reference that Service in Xamarin.Droid project.

Second, create an interface "ICustomerSoapService" and a GetAllCustomers method.

public interface ICustomer
{
string Name {get;set;}
string Id {get;set;}
}
public interface ICustomerSoapService
{
Task<List<ICustomer>> GetAllCustomers(string criteria = null);
}

Now create a class "CustomerSoapService" in Xamarin.Droid project that implements the interface "ICustomerSoapService".

[assembly: Dependency(typeof(FSL.XF2.Droid.CustomerSoapService))]
namespace FSL.XF2.Droid
{
public sealed class CustomerSoapService : ICustomerSoapService
{
CustomersWs.Customers service;
public CustomerSoapService()
{
service = new CustomersWs.Customers()
{
Url = "http://localhost/FSL.WS/Customers.asmx"
};
}
public async Task<List<ICustomer>> GetAllCustomers(string criteria = null)
{
return await Task.Run(() =>
{
var result = service.GetAllCustomers();
return new List<ICustomer>(result);
});
}
}
}

The "CustomersWs" code, mentioned above, is your Web Service reference. In your App's portable project, create a property to be injected (dependency injection) by Xamarin forms.

public partial class App : Application
{
private static ICustomerSoapService _customerSoapService;
public static ICustomerSoapService CustomerSoapService
{
get
{
if (_customerSoapService== null)
{
_customerSoapService = DependencyService.Get<ICustomerSoapService>();
}
return _customerSoapService;
}
}
}

The property, mentioned above, is a lazy loader and this will be injected by Xamarin Forms only if someone uses it. Finally, you will call the method which you want in your view.

var customers = await App.CustomerSoapService.GetAllCustomers();

Download the full source code.

I hope it helps.

Enjoy and good luck.