What i'm trying to do is transfer an image from the web service to the mobile client. In order to do this i've created a web service operation that returns a byte[] variable. In this method i create an .png image from a chart. After this i get the bytes from the image and provide them as a return value for the operation. this is the server code:
public byte[] getBytes() throws IOException {
BufferedImage chartImage = chart.createBufferedImage(230, 260);
//I get the image from a chart component.
ByteArrayOutputStream baos = new ByteArrayOutputStream(1000);
ImageIO.write( chartImage, "png",baos );
baos.flush();
byte[] bytesImage = baos.toByteArray();
baos.close();
return bytesImage;
}
Now in the mobile application all i do is assign a byte[] variable the return value of the web service operation.
byte[] imageBytes = Stub.getBytes().
Maybe i'm missing something but this is not working as i get this runtime error:
java.rmi.MarshalException: Expected Byte, received: iVBORw0KGgoAAAANSUhEU.... (very long line).
have any ideas why this happends? Or maybe you can suggest any other way to send the data to the mobile client.
If the service is only delivering an image as a byte array, the overhead induces by wrapping this in a SOAP response and XML/SOAP parsing on the client side seem rather unnecessary. Why don't you implement the chart generation in a servlet and let the client retrieve the image from a 'non-SOAP' server URL?
Instead of returning bytesImage from a WebService method like you do, you could instead write the byte array to the servlet's response object:
response.setContentType("image/png");
response.setContentLength(bytesImage.length);
OutputStream os = response.getOutputStream();
os.write(bytesImage);
os.close();
On the J2ME client, you would read the response from the URL, to which the servlet is bound and create an image from the data:
HttpConnection conn = (HttpConnection)Connector.open("http://<servlet-url>");
DataInputStream dis = conn.openDataInputStream();
byte[] buffer = new byte[conn.getLength()];
dis.readFully(buffer);
Image image = Image.createImage(buffer, 0, buffer.length);
Hope this helps!