SimpleTCPXMLElement.java

/*
 * Copyright 2009 VoidSearch.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.voidsearch.voidbase.quant.feed;

import com.voidsearch.voidbase.quant.timeseries.SequenceGenerator;
import com.voidsearch.voidbase.client.SimpleHttpClient;
import com.voidsearch.voidbase.client.SimpleTCPClient;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathConstants;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;

import java.io.DataInputStream;
import java.io.ByteArrayInputStream;

public class SimpleTCPXMLElement implements SequenceGenerator {

  String host;
  int port;
  String command;
  String xmlPath;

  public SimpleTCPXMLElement(String host, String port, String command, String elementPath) {

    this.host = host;
    this.port = Integer.parseInt(port.trim());
    this.command = command;
    this.xmlPath = elementPath;
    
  }

  public double next() {
    try {
      SimpleTCPClient client = new SimpleTCPClient(host, port);
      byte[] content = client.get(command);
      DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder builder = domFactory.newDocumentBuilder();
      Document doc = builder.parse(new DataInputStream(new ByteArrayInputStream(content)));
      XPath xpath = XPathFactory.newInstance().newXPath();

      StringBuilder xpathExpression = new StringBuilder();
      xpathExpression.append("//");

      String[] parts = xmlPath.split("\\.");

      for (String part : parts) {
        xpathExpression.append(part).append("/");
      }
      xpathExpression.append("text()");

      XPathExpression expr = xpath.compile(xpathExpression.toString());

      Object result = expr.evaluate(doc, XPathConstants.NODESET);
      NodeList nodes = (NodeList) result;

      if (nodes.getLength() == 1) {
        return Double.parseDouble(nodes.item(0).getNodeValue());
      } else {
        return 0;
      }

    } catch (Exception e) {
      e.printStackTrace();
      return 0;
    }
  }


}