Basic KSOAP Android Tutorial

This is a basic KSOAP Android tutorial - here I will show you how to get started with KSOAP on Android. As you may know, we often want to access Web services via hand-held devices, and most likely you will run into trouble parsing the WSDL and the SOAP messages. Since I come from a .NET background, once I started developing on Android, I realized how much work has been Visual Studio doing for me.

That thought took me to search for a framework or library to help me consume Web Services with Android. I ran into KSOAP2, which seemed like a good library, but unfortunately, very badly documented for most scenarios, like passing or returning complex objects, working with arrays of objects or even working with dates.

All of this I needed to find out by myself and this is why I decided to write this tutorial. So, let's begin.

Getting Started with KSOAP on Android

First things first, so you should now go ahead and download the KSOAP library from Sourceforge Google code (*UPDATE* thanks Freddy):
http://code.google.com/p/ksoap2-android/downloads/detail?name=ksoap2-android-assembly-2.4-jar-with-dependencies.jar&can=2&q=


Then copy and paste the KSOAP library in the folder where your Android project will reside. Open Eclipse, start a new Android Project, right-click on the project's name and choose Properties, like this:

The next thing you need to do is to Add the KSOAP .JAR into the Android Project:

Implementing KSOAP Marshal Interface

Another poorly documented spot in KSOAP: marshaling arguments. In KSOAP, you need to implement an interface called Marshal so that the XML parser would know how to serialize and deserialize objects you are trying to pass through the web service.

Strangely enough, object types like "double" and "Date" need to be manually marshaled! This is why I decided my code examples to show how to marshal dates and doubles. So here it goes:

package Marshals;

import java.io.IOException;

import org.ksoap2.serialization.Marshal;
import org.ksoap2.serialization.PropertyInfo;
import org.ksoap2.serialization.SoapSerializationEnvelope;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlSerializer;
/**
* 
* @author Vladimir
* Used to marshal Doubles - crucial to serialization for SOAP
*/
public class MarshalDouble implements Marshal 
{


    public Object readInstance(XmlPullParser parser, String namespace, String name, 
            PropertyInfo expected) throws IOException, XmlPullParserException {
        
        return Double.parseDouble(parser.nextText());
    }


    public void register(SoapSerializationEnvelope cm) {
         cm.addMapping(cm.xsd, "double", Double.class, this);
        
    }


    public void writeInstance(XmlSerializer writer, Object obj) throws IOException {
           writer.text(obj.toString());
        }
    
}

Returning Array of Primitive Types with KSOAP

KSOAP until recently had an issue with returning an array of primitive types. With the new patch the issue is solved. If you haven't downloaded the newest version of
KSOAP available on GitHub, you can use the following snippet:

SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);
            SoapSerializationEnvelope envelope =
            new SoapSerializationEnvelope(SoapEnvelope.VER11);
            //envelope.dotNet = true;
            envelope.setOutputSoapObject(request);
            AndroidHttpTransport androidHttpTransport = new AndroidHttpTransport(URL);
        androidHttpTransport.call(SOAP_ACTION, envelope);

                KvmSerializable ks = (KvmSerializable)envelope.bodyIn;
                for(int i=0;i<ks.getPropertyCount();i++)
                {
                   ks.getProperty(i); //if complex type is present then you can cast this to SoapObject and if primitive type is returned you can use toString() to get actuall value.
                }