locatorimpl.java

Introduction to Sybase IQ.pdf

/* Copyright (c) 2005-2008 Jan S. Rellermeyer
 * Systems Group,
 * Department of Computer Science, ETH Zurich.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *    - Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *    - Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *    - Neither the name of ETH Zurich nor the names of its contributors may be
 *      used to endorse or promote products derived from this software without
 *      specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package ch.ethz.iks.slp.impl;

import java.net.InetAddress;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;

import ch.ethz.iks.slp.Advertiser;
import ch.ethz.iks.slp.Locator;
import ch.ethz.iks.slp.ServiceLocationEnumeration;
import ch.ethz.iks.slp.ServiceLocationException;
import ch.ethz.iks.slp.ServiceType;
import ch.ethz.iks.slp.ServiceURL;

/**
 * Implementation of the Locator interface. If the configuration does not have
 * to provide UA functionalities, this class does not have to be included in the
 * distribution.
 * 
 * @see ch.ethz.iks.slp.Locator
 * @author Jan S. Rellermeyer, ETH Zurich
 * @since 0.1
 */
public final class LocatorImpl implements Locator {
	/**
	 * 
	 */
	private Locale locale;

	/**
	 * create a new LocatorImpl instance.
	 */
	public LocatorImpl() {
		locale = SLPCore.DEFAULT_LOCALE;
	}
	
	/**
	 * create a new LocatorImpl instance.
	 * 
	 * @param theLocale
	 *            the Locale for this instance.
	 */
	public LocatorImpl(final Locale locale) {
		this.locale = locale;
	}

	/**
	 * returns the locale for this instance.
	 * 
	 * @return the Locale.
	 */
	public Locale getLocale() {
		return locale;
	}

	/**
	 * Set the locale of this instance.
	 * 
	 * @param locale
	 *            the Locale.
	 * @see Advertiser#setLocale()
	 */
	public void setLocale(final Locale locale) {
		this.locale = locale;
	}

	/**
	 * find the service types.
	 * 
	 * @param namingAuthority
	 *            the naming authority.
	 * @param scopes
	 *            the scopes.
	 * @return a ServiceLocationEnumeration over the results.
	 * @throws ServiceLocationException
	 *             if something goes wrong.
	 * @see Locator#findServiceTypes(String, List)
	 */
	public ServiceLocationEnumeration findServiceTypes(
			final String namingAuthority, final List scopes)
			throws ServiceLocationException {
		RequestMessage srvTypeReq = new ServiceTypeRequest(namingAuthority,
				scopes, locale);
		return new ServiceLocationEnumerationImpl(sendRequest(srvTypeReq,
				scopes));
	}

	/**
	 * find services.
	 * 
	 * @param type
	 *            the service type.
	 * @param scopes
	 *            the scopes.
	 * @param searchFilter
	 *            an LDAP filter expression.
	 * @return a ServiceLocationEnumeration over the results.
	 * @throws ServiceLocationException
	 *             if something goes wrong.
	 * @see Locator#findAttributes(ServiceType, List, List)
	 */
	public ServiceLocationEnumeration findServices(final ServiceType type,
			final List scopes, final String searchFilter)
			throws ServiceLocationException {
		try {
			RequestMessage srvReq = new ServiceRequest(type, scopes,
					searchFilter, locale);
			return new ServiceLocationEnumerationImpl(sendRequest(srvReq,
					scopes));
		} catch (IllegalArgumentException ise) {
			throw new ServiceLocationException(
					ServiceLocationException.INTERNAL_SYSTEM_ERROR, ise
							.getMessage()
							+ ": " + searchFilter);
		}
	}

	/**
	 * find attributes by service URL.
	 * 
	 * @param url
	 *            the ServiceURL of the service.
	 * @param scopes
	 *            a List of scoped to be included.
	 * @param attributeIds
	 *            a List of attributes for which the values should be returned,
	 *            if they exist.
	 * @return ServiceLocationEnumeration over the results.
	 * @throws ServiceLocationException
	 *             in case of network errors etc.
	 * @see Locator#findAttributes(ServiceURL, List, List)
	 */
	public ServiceLocationEnumeration findAttributes(final ServiceURL url,
			final List scopes, final List attributeIds)
			throws ServiceLocationException {
		return findAttributes(new AttributeRequest(url, scopes, attributeIds,
				locale));
	}

	/**
	 * find attributes by service type.
	 * 
	 * @param type
	 *            the service type.
	 * @param scopes
	 *            the scopes.
	 * @param attributeIds
	 *            a List of attributes for which the values should be returned,
	 *            if they exist.
	 * @return a ServiceLocationEnumeration over the results.
	 * @throws ServiceLocationException
	 *             if something goes wrong.
	 * @see Locator#findAttributes(ServiceType, List, List)
	 */
	public ServiceLocationEnumeration findAttributes(final ServiceType type,
			final List scopes, final List attributeIds)
			throws ServiceLocationException {
		return findAttributes(new AttributeRequest(type, scopes, attributeIds,
				locale));
	}

	/**
	 * common method that handles a predefined AttributeRequest.
	 * 
	 * @param attReq
	 *            the AttributeRequest.
	 * @return the resulting Attributes as String.
	 * @throws ServiceLocationException
	 *             in case of network errors.
	 */
	private ServiceLocationEnumeration findAttributes(
			final AttributeRequest attReq) throws ServiceLocationException {
		return new ServiceLocationEnumerationImpl(sendRequest(attReq,
				attReq.scopeList));
	}

	/**
	 * send a request. Uses direct communication to a DA or multicast
	 * convergence, if no DA is known for the specific scope.
	 * 
	 * @param req
	 *            the request.
	 * @param scopeList
	 *            the scopes.
	 * @return the list of results.
	 * @throws ServiceLocationException
	 *             if something goes wrong.
	 */
	private List sendRequest(final RequestMessage req, final List scopeList)
			throws ServiceLocationException {
		List scopes = scopeList != null ? scopeList : Arrays
				.asList(new String[] { "default" });

		ArrayList result = new ArrayList();
		for (Iterator scopeIter = scopes.iterator(); scopeIter.hasNext();) {
			String scope = (String) scopeIter.next();
			scope = scope.toLowerCase();
			List dAs = (List) SLPCore.dAs.get(scope);

			SLPCore.platform
						.logDebug("DAS FOR SCOPE " + scope + ": " + dAs);

			// no DA for the scope known ?
			// try to find one
			if ((dAs == null || dAs.isEmpty()) && !SLPCore.noDiscovery) {
				SLPCore.daLookup(Arrays.asList(new String[] { scope }));

				// wait a short time for incoming replies
				synchronized (SLPCore.dAs) {
					try {
						SLPCore.dAs.wait(SLPCore.CONFIG.getWaitTime() / 4);
					} catch (InterruptedException e) {
						SLPCore.platform.logError(e.getMessage(), e);
						// Restore the interrupted status as we're not the owner of the current thread
						Thread.currentThread().interrupt();
					}
				}
				dAs = (List) SLPCore.dAs.get(scope);
			}

			if (dAs != null && !dAs.isEmpty()) {
				// a DA is known for this scope, so contact it
				try {
					result.addAll(sendRequestToDA(req, dAs));
				} catch (ServiceLocationException slp) {
					result.addAll(SLPCore.multicastConvergence(req));
				}
				continue;
			} else {
				if (SLPCore.noDiscovery) {
					throw new ServiceLocationException(
							ServiceLocationException.SCOPE_NOT_SUPPORTED,
							"Scope " + scope + " is not supported");
				}

				// still no DA available, use multicast
				result.addAll(SLPCore.multicastConvergence(req));
			}
		}
		return result;
	}

	/**
	 * send a request to a DA.
	 * 
	 * @param req
	 *            the request.
	 * @param dAaddresses
	 *            the DA address.
	 * @return the <code>List</code> of results.
	 * @throws ServiceLocationException
	 */
	private List sendRequestToDA(final RequestMessage req,
			final List dAaddresses) throws ServiceLocationException {
		for (int index = 0; index < dAaddresses.size(); index++) {
			ReplyMessage reply = null;
			try {
				// set the receiver address
				req.address = InetAddress.getByName((String) dAaddresses
						.get(index));
				req.port = SLPCore.SLP_RESERVED_PORT;
				reply = (ReplyMessage) SLPCore.sendMessage(req, true);
				if (reply.errorCode == 0) {
					// we could receive a valid reply from the DA
					return reply.getResult();
				}
			} catch (Exception e) {
				SLPCore.platform.logError(e.getMessage(), e
							.fillInStackTrace());
				// something went wrong.
				// remove DA from list.
				final Object url = dAaddresses.get(index);
				SLPUtils.removeValueFromAll(SLPCore.dAs, url);
				SLPCore.dASPIs.remove(url);
				// Try the next DA in the list.
				continue;
			}
		}
		// did not work. Return an empty result array.
		throw new ServiceLocationException(
				ServiceLocationException.INTERNAL_SYSTEM_ERROR,
				"No DA reachable");
	}

}