Adding XML Attriubutes to Nodes

Question

Hello,
I'm working on a project that requires parsing of messages between server and client programs and we're using XML as the language.
The server is programmed in C# and the client in Java ..
I need something like this:
<ROOM>
<TYPE message="CREATE">
// A create type message goes in here
</TYPE>
</ROOM>
The following is the method that actually creates the message (located in the client) ...
public void CreateRoomOperationMessage (String toLocation, String roomName, String messageOperation) {
        // The create room operation message is a method which creates the create/kill messages
        try {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            DOMImplementation impl = builder.getDOMImplementation();
            Document doc = impl.createDocument(null, toLocation, null);
            Node rootElement = doc.getDocumentElement();
            Node roomNode = doc.createElement(ROOM);
            rootElement.appendChild(roomNode);
            Node typeNode = doc.createElement(TYPE);
            roomNode.appendChild(typeNode);
            //Element typeElement = doc.getElementsByTagName(TYPE);
            //typeElement.setAttribute("MESSAGE", messageOperation);
            // PROBLEM ... NEED TO FIGURE OUT HOW TO INSERT AN ELEMENT INTO THE TREE?
            Text typeText = doc.createTextNode(messageOperation);
            typeNode.appendChild(typeText);
            Node roomNameNode = doc.createElement(ROOMNAME);
            roomNode.appendChild(roomNameNode);
            Text roomNameText = doc.createTextNode(roomName);
            roomNameNode.appendChild(roomNameText);
            TransformerFactory xformFactory = TransformerFactory.newInstance();
            Transformer idTransform = xformFactory.newTransformer();
            Source input = new DOMSource(doc);
            Writer txtWriter = new StringWriter();
            Result output = new StreamResult(txtWriter);
            idTransform.transform(input, output);
            setXmlMessage(txtWriter.toString());
        } catch (FactoryConfigurationError e) {
            System.err.println("ROOMMESSAGEFACTORY: Could not locate a JAXP factory class");
        } catch (ParserConfigurationException e) {
            System.err.println("ROOMMESSAGEFACTORY: Could not locate a JAXP DocumentBuilder class");
        } catch (DOMException e) {
            System.err.println("ROOMMESSAGEFACTORY: DOM Exception");
            System.err.println(e);
        } catch (TransformerConfigurationException e) {
            System.err.println("ROOMMESSAGEFACTORY: Input to Output transformation error!");
            System.err.println(e);
        } catch (TransformerException e) {
            System.err.println("ROOMMESSAGEFACTORY: Transformer Exception");
            System.err.println(e);
    }I just don't see any way of taking a node and setting/adding an attribute ...
eg .. Node typeNode = doc.createElement(TYPE);
roomNode.appendChild(typeNode);
typeNode.setAttribute("message", messageOperation); // This is the pseudocode

Answer 1

The return value of createElement() is an Element, and Element has a setAttribute method. Just don't implicitly upcast to Node and your pseudocode is correct.Element  typeNode = doc.createElement(TYPE);
roomNode.appendChild(typeNode);
typeNode.setAttribute("message", messageOperation);Pete