QWEmbeddedMsgProcessor.java

/*
 * EIDSMsgProcessor
 */
package gov.usgs.earthquake.eidsutil;

import com.isti.quakewatch.message.MsgProcessorInterface;

import org.jdom.Attribute;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.output.XMLOutputter;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Date;

/**
 * Adapts the ISTI MsgProcessorInterface for EIDSClient. When the EIDSClient
 * receives a message, the processDataMessage method is invoked.
 * 
 * @see EIDSClient
 */
class QWEmbeddedMsgProcessor implements MsgProcessorInterface {

    /** The client to notify when messages are available. */
    private QWEmbeddedClient client;

    /**
     * Construct a new EIDSMsgProcessor.
     * 
     * @param client
     *            the client that uses this processor.
     */
    public QWEmbeddedMsgProcessor(final QWEmbeddedClient client) {
        this.client = client;
    }

    /**
     * Convert QWmessages to QWMsgRecords. Override the notifyMessage method to
     * further process messages before sending to listeners.
     * 
     * @param qwMsgElement
     *            The "QWmessage" element.
     * @param dataMsgElement
     *            The "DataMessage" element.
     * @param xmlMsgStr
     *            the XML text message string.
     * @param requestedFlag
     *            true to indicate the the message was "requested" (and that it
     *            should not be processed as a "real-time" message).
     * @param msgNumObj
     *            a 'Long' object holding the message number for the message, or
     *            null if a message number is not available.
     * @param timeGenObj
     *            a 'Date' object holding the time-generated value for the
     *            message, or null if a time-generated value is not available.
     */
    public void processDataMessage(Element qwMsgElement,
            Element dataMsgElement, String xmlMsgStr, boolean requestedFlag,
            Long msgNumObj, Date timeGenObj) {
        // extract unique message id
        String fdrSourceHost = getAttribute(qwMsgElement, "FdrSourceHost");
        Long fdrSourceMsgNum = Long.valueOf(getAttribute(qwMsgElement,
                "FdrSourceMsgNum"));

        Element root = (Element) dataMsgElement.getChildren().get(0);
        String rootElement = root.getName();
        String rootNamespace = root.getNamespaceURI();

        client.onEIDSMessage(new EIDSMessageEvent(client, msgNumObj,
                timeGenObj, fdrSourceHost, fdrSourceMsgNum, rootNamespace,
                rootElement, getXML(root)));
    }

    /**
     * Extract a JDOM attribute value.
     * 
     * @param element
     *            a JDOM element
     * @param name
     *            the attribute name
     * @return the attribute value, or null if not present.
     */
    public String getAttribute(final Element element, final String name) {
        Attribute attribute = element.getAttribute(name);
        String value = null;
        if (attribute != null) {
            value = attribute.getValue();
        }
        return value;
    }

    /**
     * Serialize an element to an outputstream.
     * 
     * @param element
     *            element to serialize.
     * @param out
     *            outputstream where serialized element is written.s
     */
    public static void writeXML(final Element element, final OutputStream out) {
        try {
            Document doc = new Document((Element) element.clone());
            XMLOutputter outputter = new XMLOutputter();
            outputter.output(doc, out);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * Serialize an element into a String.
     * 
     * @param element
     *            element to serialize.
     */
    public static String getXML(final Element element) {
        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            writeXML(element, baos);
            return baos.toString();
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }
}