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Core functionality used by all other modules.
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/**
 * Copyright (C) 2012 - 2013 Xeiam LLC http://xeiam.com
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package com.xeiam.xchange;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.xeiam.xchange.utils.Assert;

/**
 * 
 * Factory to provide the following to {@link Exchange}:
 * 
 * 
 * Manages the creation of specific Exchange implementations using runtime dependencies
 * 
 */
public enum ExchangeFactory {

  INSTANCE;

  private final Logger log = LoggerFactory.getLogger(ExchangeFactory.class);

  /**
   * Constructor
   */
  private ExchangeFactory() {

  }

  /**
   * Create an Exchange object
   * 
   * @param exchangeClassName
   * @return
   */
  public Exchange createExchange(String exchangeClassName) {

    Assert.notNull(exchangeClassName, "exchangeClassName cannot be null");

    log.debug("Creating default exchange from class name");

    // Attempt to create an instance of the exchange provider
    try {

      // Attempt to locate the exchange provider on the classpath
      Class exchangeProviderClass = Class.forName(exchangeClassName);

      // Test that the class implements Exchange
      if (Exchange.class.isAssignableFrom(exchangeProviderClass)) {
        // Instantiate through the default constructor and use the default exchange specification
        Exchange exchange = (Exchange) exchangeProviderClass.newInstance();
        exchange.applySpecification(exchange.getDefaultExchangeSpecification());
        return exchange;
      } else {
        throw new ExchangeException("Class '" + exchangeClassName + "' does not implement Exchange");
      }
    } catch (ClassNotFoundException e) {
      throw new ExchangeException("Problem creating Exchange (class not found)", e);
    } catch (InstantiationException e) {
      throw new ExchangeException("Problem creating Exchange (instantiation)", e);
    } catch (IllegalAccessException e) {
      throw new ExchangeException("Problem creating Exchange (illegal access)", e);
    }

    // Cannot be here due to exceptions

  }

  public Exchange createExchange(ExchangeSpecification exchangeSpecification) {

    Assert.notNull(exchangeSpecification, "exchangeSpecfication cannot be null");

    log.debug("Creating exchange from specification");

    String exchangeClassName = exchangeSpecification.getExchangeClassName();

    // Attempt to create an instance of the exchange provider
    try {

      // Attempt to locate the exchange provider on the classpath
      Class exchangeProviderClass = Class.forName(exchangeClassName);

      // Test that the class implements Exchange
      if (Exchange.class.isAssignableFrom(exchangeProviderClass)) {
        // Instantiate through the default constructor
        Exchange exchange = (Exchange) exchangeProviderClass.newInstance();
        exchange.applySpecification(exchangeSpecification);
        return exchange;
      } else {
        throw new ExchangeException("Class '" + exchangeClassName + "' does not implement Exchange");
      }
    } catch (ClassNotFoundException e) {
      throw new ExchangeException("Problem starting exchange provider (class not found)", e);
    } catch (InstantiationException e) {
      throw new ExchangeException("Problem starting exchange provider (instantiation)", e);
    } catch (IllegalAccessException e) {
      throw new ExchangeException("Problem starting exchange provider (illegal access)", e);
    }

    // Cannot be here due to exceptions

  }

}