Android Web Service Client

Constant	Description
NAMESPACE	Namespace is the targetNamespace in the WSDL.
URL	The WSDL URL. Its value is the location attribute of the soap:address element for a port element in a WSDL. Unless the web service is also hosted on the Android device, the hostname should not be specified as localhost, because the application runs on the Android device while the web service is hosted on the localhost server. Specify hostname as the IP address of the server hosting the web service.
METHOD_NAME	The name of the web service operation, which may be obtained form the WSDL.
SOAP_ACTION	NAMESPACE+METHOD_NAME specified as a String literal.

The constant values are as follows; the IP address for the URL constant would vary:

private static final String NAMESPACE = "http://hello_webservice/"; private static String URL="http://192.168.1.68:7001/HelloWebService/HelloWSService?WSDL"; private static final String METHOD_NAME = "hello"; private static final String SOAP_ACTION = "http://hello_webservice/hello";

All Activities must implement the onCreate method for activity initialization. Define the UI using the setContentView method and the layout resource.

setContentView(R.layout.main);

Create an Android widget TextView object using the findViewById method on the TextView element defined in the main.xml.

TextView lblResult = (TextView) findViewById(R.id.result);

Create a org.ksoap2.serialization.SoapObject object to build a SOAP request. Specify the namespace of the SOAP object and method name to be invoked in the SoapObject constructor.

SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);

Create a org.ksoap2.serialization.PropertyInfo object to contain property information to be sent with the SOAP method call. Each property requires a new PropertyInfo object. The hello method takes only 1 argument for a name. Set the property name as "arg0", and specify the type of the property as STRING_CLASS. Add the PropertyInfo object to the SoapObject using the addProperty method.

PropertyInfo propInfo=new PropertyInfo(); propInfo.name="arg0"; propInfo.type=PropertyInfo.STRING_CLASS; request.addProperty(propInfo, "John Smith");

Next create a SOAP envelop. Use the SoapSerializationEnvelope class, which extends the SoapEnvelop class, with support for SOAP Serialization format, which represents the structure of a SOAP serialized message. The main advantage of SOAP serialization is portability.

SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);

The constant SoapEnvelope.VER11 indicates SOAP Version 1.1. Assign the SoapObject request object to the envelop as the outbound message for the SOAP method call.

envelope.setOutputSoapObject(request);

Create a org.ksoap2.transport.HttpTransportSE object that represents a J2SE based HttpTransport layer.HttpTransportSE extends the org.ksoap2.transport.Transport class, which encapsulates the serialization and deserialization of SOAP messages.

HttpTransportSE androidHttpTransport = new HttpTransportSE(URL);

Make the soap call using the SOAP_ACTION and the soap envelop.

androidHttpTransport.call(SOAP_ACTION, envelope);

Get the web service response using the getResponse method of the SoapSerializationEnvelope object and cast the response object to SoapPrimitive, class used to encapsulate primitive types.

SoapPrimitive resultsRequestSOAP = (SoapPrimitive) envelope.getResponse();

Set the String message in the SOAP response in the TextView UI component.

lblResult.setText(resultsRequestSOAP.toString());

The Activity class is listed below in Listing 4.

Listing 4. Activity Class AndroidWSClient.java

package android.webservice.client; import org.ksoap2.SoapEnvelope; import org.ksoap2.serialization.SoapObject; import org.ksoap2.serialization.SoapPrimitive; import org.ksoap2.serialization.SoapSerializationEnvelope; import org.ksoap2.transport.HttpTransportSE; import org.ksoap2.serialization.PropertyInfo; import android.widget.TextView; import android.app.Activity; import android.os.Bundle; import android.widget.ArrayAdapter; import android.widget.AutoCompleteTextView; public class AndroidWSClient extends Activity { private static final String NAMESPACE = "http://hello_webservice/"; private static String URL = "http://192.168.1.68:7001/HelloWebService/ HelloWSService?WSDL"; private static final String METHOD_NAME = "hello"; private static final String SOAP_ACTION = "http://hello_webservice/hello"; private TextView lblResult; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); lblResult = (TextView) findViewById(R.id.result); SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME); PropertyInfo propInfo=new PropertyInfo(); propInfo.name="arg0"; propInfo.type=PropertyInfo.STRING_CLASS; request.addProperty(propInfo, "John Smith"); SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); envelope.setOutputSoapObject(request); HttpTransportSE androidHttpTransport = new HttpTransportSE(URL); try { androidHttpTransport.call(SOAP_ACTION, envelope); SoapPrimitive resultsRequestSOAP = (SoapPrimitive) envelope.getResponse(); lblResult.setText(resultsRequestSOAP.toString()); } catch (Exception e) { } } }