001/*
002 * Copyright 2008-2017 UnboundID Corp.
003 * All Rights Reserved.
004 */
005/*
006 * Copyright (C) 2008-2017 UnboundID Corp.
007 *
008 * This program is free software; you can redistribute it and/or modify
009 * it under the terms of the GNU General Public License (GPLv2 only)
010 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
011 * as published by the Free Software Foundation.
012 *
013 * This program is distributed in the hope that it will be useful,
014 * but WITHOUT ANY WARRANTY; without even the implied warranty of
015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
016 * GNU General Public License for more details.
017 *
018 * You should have received a copy of the GNU General Public License
019 * along with this program; if not, see <http://www.gnu.org/licenses>.
020 */
021package com.unboundid.ldap.sdk;
022
023
024
025import com.unboundid.util.Extensible;
026import com.unboundid.util.ThreadSafety;
027import com.unboundid.util.ThreadSafetyLevel;
028
029import static com.unboundid.util.Debug.*;
030
031
032
033/**
034 * This class defines an API that can be used to select between multiple
035 * directory servers when establishing a connection.  Implementations are free
036 * to use any kind of logic that they desire when selecting the server to which
037 * the connection is to be established.  They may also support the use of
038 * health checks to determine whether the created connections are suitable for
039 * use.
040 * <BR><BR>
041 * Implementations MUST be threadsafe to allow for multiple concurrent attempts
042 * to establish new connections.
043 */
044@Extensible()
045@ThreadSafety(level=ThreadSafetyLevel.INTERFACE_THREADSAFE)
046public abstract class ServerSet
047{
048  /**
049   * Creates a new instance of this server set.
050   */
051  protected ServerSet()
052  {
053    // No implementation is required.
054  }
055
056
057
058  /**
059   * Attempts to establish a connection to one of the directory servers in this
060   * server set.  The connection should be established but unauthenticated.  The
061   * caller may determine the server to which the connection is established
062   * using the {@link LDAPConnection#getConnectedAddress} and
063   * {@link LDAPConnection#getConnectedPort} methods.
064   *
065   * @return  An {@code LDAPConnection} object that is established to one of the
066   *          servers in this server set.
067   *
068   * @throws  LDAPException  If it is not possible to establish a connection to
069   *                         any of the servers in this server set.
070   */
071  public abstract LDAPConnection getConnection()
072         throws LDAPException;
073
074
075
076  /**
077   * Attempts to establish a connection to one of the directory servers in this
078   * server set, using the provided health check to further validate the
079   * connection.  The connection should be established but unauthenticated.
080   * The caller may determine the server to which the connection is established
081   * using the {@link LDAPConnection#getConnectedAddress} and
082   * {@link LDAPConnection#getConnectedPort} methods.
083   *
084   * @param  healthCheck  The health check to use to make the determination, or
085   *                      {@code null} if no additional health check should be
086   *                      performed.
087   *
088   * @return  An {@code LDAPConnection} object that is established to one of the
089   *          servers in this server set.
090   *
091   * @throws  LDAPException  If it is not possible to establish a connection to
092   *                         any of the servers in this server set.
093   */
094  public LDAPConnection getConnection(
095                             final LDAPConnectionPoolHealthCheck healthCheck)
096         throws LDAPException
097  {
098    final LDAPConnection c = getConnection();
099
100    if (healthCheck != null)
101    {
102      try
103      {
104        healthCheck.ensureNewConnectionValid(c);
105      }
106      catch (LDAPException le)
107      {
108        debugException(le);
109        c.close();
110        throw le;
111      }
112    }
113
114    return c;
115  }
116
117
118
119  /**
120   * Retrieves a string representation of this server set.
121   *
122   * @return  A string representation of this server set.
123   */
124  @Override()
125  public String toString()
126  {
127    final StringBuilder buffer = new StringBuilder();
128    toString(buffer);
129    return buffer.toString();
130  }
131
132
133
134  /**
135   * Appends a string representation of this server set to the provided buffer.
136   *
137   * @param  buffer  The buffer to which the string representation should be
138   *                 appended.
139   */
140  public void toString(final StringBuilder buffer)
141  {
142    buffer.append("ServerSet(className=");
143    buffer.append(getClass().getName());
144    buffer.append(')');
145  }
146}