org.epics.archiverappliance.retrieval.channelarchiver.XMLRPCClient.java Source code

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Here is the source code for org.epics.archiverappliance.retrieval.channelarchiver.XMLRPCClient.java

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/*******************************************************************************
 * Copyright (c) 2011 The Board of Trustees of the Leland Stanford Junior University
 * as Operator of the SLAC National Accelerator Laboratory.
 * Copyright (c) 2011 Brookhaven National Laboratory.
 * EPICS archiver appliance is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution.
 *******************************************************************************/
package org.epics.archiverappliance.retrieval.channelarchiver;

import java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.log4j.Logger;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * A class that handles the XML-RPC portion of an existing channel archiver instance.
 * We pass in a SAXParser for all method calls; theoretically, this should be accommodate passing data out of the system in a streaming fashion  
 * 
 * @author mshankar
 *
 */
public class XMLRPCClient {
    private static Logger logger = Logger.getLogger(XMLRPCClient.class.getName());

    /**
     * Internal method to make a XML_RPC post call and call the SAX handler on the returned document.
     * @param serverURL The Server URL
     * @param handler  DefaultHandler 
     * @param postEntity StringEntity 
     * @throws IOException    
     * @throws SAXException    
     */
    private static void doHTTPPostAndCallSAXHandler(String serverURL, DefaultHandler handler,
            StringEntity postEntity) throws IOException, SAXException {
        logger.debug("Executing doHTTPPostAndCallSAXHandler with the server URL " + serverURL);
        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpPost postMethod = new HttpPost(serverURL);
        postMethod.addHeader("Content-Type", "text/xml");
        postMethod.setEntity(postEntity);
        logger.debug("Executing the HTTP POST" + serverURL);
        HttpResponse response = httpclient.execute(postMethod);
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            logger.debug("Obtained a HTTP entity of length " + entity.getContentLength());
            try (InputStream is = entity.getContent()) {
                SAXParserFactory sfac = SAXParserFactory.newInstance();
                sfac.setNamespaceAware(false);
                sfac.setValidating(false);
                SAXParser parser = sfac.newSAXParser();
                parser.parse(is, handler);
            } catch (ParserConfigurationException pex) {
                throw new IOException(pex);
            }
        } else {
            throw new IOException("HTTP response did not have an entity associated with it");
        }
    }

    /**
     * Call archiver.info on the Channel Archiver
     * @param serverURL  The Server URL 
     * @param handler  DefaultHandler  
     * @throws IOException   
     * @throws SAXException   
     */
    public static void archiverInfo(String serverURL, DefaultHandler handler) throws IOException, SAXException {
        logger.debug("Getting channel archiver info with URL " + serverURL);
        StringEntity archiverInfo = new StringEntity("<?xml version=\"1.0\"?>\n" + "<methodCall>\n"
                + "<methodName>archiver.info</methodName>\n" + "<params></params>\n" + "</methodCall>\n",
                ContentType.APPLICATION_XML);
        doHTTPPostAndCallSAXHandler(serverURL, handler, archiverInfo);
    }

    /**
     * Call archiver.archives on the Channel Archiver
     * @param serverURL The Server URL 
     * @param handler  DefaultHandler  
     * @throws IOException  &emsp; 
     * @throws SAXException  &emsp; 
     */
    public static void archiverArchives(String serverURL, DefaultHandler handler) throws IOException, SAXException {
        logger.debug("Getting channel archiver archives with URL " + serverURL);
        StringEntity archiverInfo = new StringEntity("<?xml version=\"1.0\"?>\n" + "<methodCall>\n"
                + "<methodName>archiver.archives</methodName>\n" + "<params></params>\n" + "</methodCall>\n",
                ContentType.APPLICATION_XML);
        doHTTPPostAndCallSAXHandler(serverURL, handler, archiverInfo);
    }

    /**
     * Call archiver.names on the Channel Archiver - note this call can take a loooong time.
     * @param serverURL The Server URL 
     * @param key  &emsp; 
     * @param handler  DefaultHandler  
     * @throws IOException  &emsp; 
     * @throws SAXException  &emsp; 
     */
    public static void archiverNames(String serverURL, String key, DefaultHandler handler)
            throws IOException, SAXException {
        logger.debug("Getting channel archiver archives with URL " + serverURL);
        StringEntity archiverInfo = new StringEntity(
                "<?xml version=\"1.0\"?>\n" + "<methodCall>\n" + "<methodName>archiver.names</methodName>\n"
                        + "<params>\n" + "<param><value><i4>" + key + "</i4></value></param>\n"
                        + "<param><value><string></string></value></param>" + "</params>\n" + "</methodCall>\n",
                ContentType.APPLICATION_XML);
        doHTTPPostAndCallSAXHandler(serverURL, handler, archiverInfo);
    }
}