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1 <html> |
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2 <head> |
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3 <title>RMI connector</title> |
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4 <!-- |
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5 Copyright 2002-2006 Sun Microsystems, Inc. All Rights Reserved. |
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6 DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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8 This code is free software; you can redistribute it and/or modify it |
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11 particular file as subject to the "Classpath" exception as provided |
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12 by Sun in the LICENSE file that accompanied this code. |
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14 This code is distributed in the hope that it will be useful, but WITHOUT |
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15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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17 version 2 for more details (a copy is included in the LICENSE file that |
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18 accompanied this code). |
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20 You should have received a copy of the GNU General Public License version |
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22 Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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24 Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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25 CA 95054 USA or visit www.sun.com if you need additional information or |
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26 have any questions. |
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27 --> |
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28 </head> |
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29 <body bgcolor="white"> |
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30 <p>The RMI connector is a connector for the JMX Remote API that |
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31 uses RMI to transmit client requests to a remote MBean server. |
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32 This package defines the classes that the user of an RMI |
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33 connector needs to reference directly, for both the client and |
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34 server sides. It also defines certain classes that the user |
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35 will not usually reference directly, but that must be defined so |
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36 that different implementations of the RMI connector can |
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37 interoperate.</p> |
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38 |
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39 <p>The RMI connector supports both the JRMP and the IIOP transports |
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40 for RMI.</p> |
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41 |
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42 <p>Like most connectors in the JMX Remote API, an RMI connector |
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43 usually has an address, which |
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44 is a {@link javax.management.remote.JMXServiceURL |
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45 JMXServiceURL}. The protocol part of this address is |
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46 <code>rmi</code> for a connector that uses the default RMI |
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47 transport (JRMP), or <code>iiop</code> for a connector that |
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48 uses RMI/IIOP.</p> |
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49 |
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50 <p>There are two forms for RMI connector addresses:</p> |
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51 |
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52 <ul> |
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53 <li> |
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54 In the <em>JNDI form</em>, the URL indicates <em>where to find |
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55 an RMI stub for the connector</em>. This RMI stub is a Java |
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56 object of type {@link javax.management.remote.rmi.RMIServer |
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57 RMIServer} that gives remote access to the connector server. |
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58 With this address form, the RMI stub is obtained from an |
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59 external directory entry included in the URL. An external |
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60 directory is any directory recognized by {@link javax.naming |
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61 JNDI}, typically the RMI registry, LDAP, or COS Naming. |
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62 |
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63 <li> |
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64 In the <em>encoded form</em>, the URL directly includes the |
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65 information needed to connect to the connector server. When |
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66 using RMI/JRMP, the encoded form is the serialized RMI stub |
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67 for the server object, encoded using BASE64 without embedded |
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68 newlines. When using RMI/IIOP, the encoded form is the CORBA |
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69 IOR for the server object. |
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70 </ul> |
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71 |
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72 <p>Addresses are covered in more detail below.</p> |
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73 |
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74 |
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75 <h3>Creating an RMI connector server</h3> |
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76 |
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77 <p>The usual way to create an RMI connector server is to supply an |
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78 RMI connector address to the method {@link |
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79 javax.management.remote.JMXConnectorServerFactory#newJMXConnectorServer |
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80 JMXConnectorServerFactory.newJMXConnectorServer}. The MBean |
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81 server to which the connector server is attached can be |
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82 specified as a parameter to that method. Alternatively, the |
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83 connector server can be registered as an MBean in that MBean |
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84 server.</p> |
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85 |
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86 <p>An RMI connector server can also be created by constructing an |
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87 instance of {@link |
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88 javax.management.remote.rmi.RMIConnectorServer |
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89 RMIConnectorServer}, explicitly or through the MBean server's |
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90 <code>createMBean</code> method.</p> |
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91 |
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92 <h4>Choosing the RMI transport</h4> |
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93 |
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94 <p>You can choose the RMI transport (JRMP or IIOP) by specifying |
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95 <code>rmi</code> or <code>iiop</code> in the |
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96 <code><em>protocol</em></code> part of the |
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97 <code>serviceURL</code> when creating the connector server. You |
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98 can also create specialised connector servers by instantiating |
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99 an appropriate subclass of {@link |
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100 javax.management.remote.rmi.RMIServerImpl RMIServerImpl} and |
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101 supplying it to the <code>RMIConnectorServer</code> |
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102 constructor.</p> |
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103 |
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104 |
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105 <h4><a name="servergen">Connector addresses generated by the |
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106 server</a></h4> |
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107 |
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108 <p>If the <code>serviceURL</code> you specify has an empty URL |
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109 path (after the optional host and port), or if you do not |
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110 specify a <code>serviceURL</code>, then the connector server |
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111 will fabricate a new <code>JMXServiceURL</code> that clients can |
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112 use to connect:</p> |
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113 |
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114 <ul> |
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115 |
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116 <li><p>If the <code>serviceURL</code> looks like:</p> |
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117 |
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118 <pre> |
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119 <code>service:jmx:rmi://<em>host</em>:<em>port</em></code> |
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120 </pre> |
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121 |
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122 <p>then the connector server will generate an {@link |
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123 javax.management.remote.rmi.RMIJRMPServerImpl |
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124 RMIJRMPServerImpl} and the returned <code>JMXServiceURL</code> |
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125 looks like:</p> |
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126 |
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127 <pre> |
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128 <code>service:jmx:rmi://<em>host</em>:<em>port</em>/stub/<em>XXXX</em></code> |
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129 </pre> |
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130 |
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131 <p>where <code><em>XXXX</em></code> is the serialized form of the |
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132 stub for the generated object, encoded in BASE64 without |
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133 newlines.</p> |
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134 |
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135 <li><p>If the <code>serviceURL</code> looks like:</p> |
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136 |
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137 <pre> |
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138 <code>service:jmx:iiop://<em>host</em>:<em>port</em></code> |
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139 </pre> |
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140 |
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141 <p>then the connector server will generate an {@link |
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142 javax.management.remote.rmi.RMIIIOPServerImpl |
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143 RMIIIOPServerImpl} and the returned |
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144 <code>JMXServiceURL</code> looks like:</p> |
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145 |
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146 <pre> |
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147 <code>service:jmx:iiop://<em>host</em>:<em>port</em>/ior/IOR:<em>XXXX</em></code> |
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148 </pre> |
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149 |
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150 <p>where <code>IOR:<em>XXXX</em></code> is the standard CORBA |
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151 encoding of the Interoperable Object Reference for the |
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152 generated object.</p> |
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153 |
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154 <li><p>If there is no <code>serviceURL</code>, there must be a |
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155 user-provided <code>RMIServerImpl</code>. If the {@link |
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156 javax.management.remote.rmi.RMIServerImpl#toStub toStub} |
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157 method on this object returns an instance of {@link |
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158 javax.rmi.CORBA.Stub}, then the connector server will generate |
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159 a <code>JMXServiceURL</code> using the <code>iiop</code> |
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160 form above. Otherwise, it will generate a |
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161 <code>JMXServiceURL</code> using the <code>rmi</code> |
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162 form.</p> |
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163 |
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164 </ul> |
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165 |
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166 <p>The <code><em>host</em></code> in a user-provided |
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167 <code>serviceURL</code> is optional. If present, it is copied |
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168 into the generated <code>JMXServiceURL</code> but otherwise |
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169 ignored. If absent, the generated <code>JXMServiceURL</code> |
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170 will have the local host name.</p> |
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171 |
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172 <p>The <code><em>port</em></code> in a user-provided |
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173 <code>serviceURL</code> is also optional. If present, it is |
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174 also copied into the generated <code>JMXServiceURL</code>; |
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175 otherwise, the generated <code>JMXServiceURL</code> has no port. |
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176 For an <code>serviceURL</code> using the <code>rmi</code> |
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177 protocol, the <code><em>port</em></code>, if present, indicates |
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178 what port the generated remote object should be exported on. It |
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179 has no other effect.</p> |
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180 |
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181 <p>If the user provides an <code>RMIServerImpl</code> rather than a |
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182 <code>JMXServiceURL</code>, then the generated |
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183 <code>JMXServiceURL</code> will have the local host name in its |
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184 <code><em>host</em></code> part and no |
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185 <code><em>port</em></code>.</p> |
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186 |
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187 |
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188 <h4><a name="directory">Connector addresses based on directory |
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189 entries</a></h4> |
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190 |
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191 <p>As an alternative to the generated addresses just described, |
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192 the <code>serviceURL</code> address supplied when creating a |
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193 connector server can specify a <em>directory address</em> in |
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194 which to store the provided or generated <code>RMIServer</code> |
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195 stub. This directory address is then used by both client and |
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196 server.</p> |
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197 |
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198 <p>In this case, the <code>serviceURL</code> has one of these two |
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199 forms:</p> |
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200 |
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201 <pre> |
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202 <code>service:jmx:rmi://<em>host</em>:<em>port</em>/jndi/<em>jndi-name</em></code> |
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203 <code>service:jmx:iiop://<em>host</em>:<em>port</em>/jndi/<em>jndi-name</em></code> |
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204 </pre> |
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205 |
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206 <p>Here, <code><em>jndi-name</em></code> is a string that can be |
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207 supplied to {@link javax.naming.InitialContext#bind |
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208 javax.naming.InitialContext.bind}.</p> |
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209 |
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210 <p>As usual, the <code><em>host</em></code> and |
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211 <code>:<em>port</em></code> can be omitted.</p> |
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212 |
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213 <p>The connector server will generate an |
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214 <code>RMIServerImpl</code> based on the protocol |
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215 (<code>rmi</code> or <code>iiop</code>) and, for |
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216 <code>rmi</code>, the <code><em>port</em></code> if any. When |
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217 the connector server is started, it will derive a stub from this |
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218 object using its {@link |
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219 javax.management.remote.rmi.RMIServerImpl#toStub toStub} method |
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220 and store the object using the given |
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221 <code><em>jndi-name</em></code>. The properties defined by the |
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222 JNDI API are consulted as usual.</p> |
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223 |
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224 <p>For example, if the <code>JMXServiceURL</code> is: |
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225 |
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226 <pre> |
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227 <code>service:jmx:rmi://ignoredhost/jndi/rmi://myhost/myname</code> |
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228 </pre> |
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229 |
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230 then the connector server will generate an |
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231 <code>RMIJRMPServerImpl</code> and store its stub using the JNDI |
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232 name |
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233 |
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234 <pre> |
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235 <code>rmi://myhost/myname</code> |
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236 </pre> |
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237 |
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238 which means entry <code>myname</code> in the RMI registry |
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239 running on the default port of host <code>myhost</code>. Note |
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240 that the RMI registry only allows registration from the local |
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241 host. So, in this case, <code>myhost</code> must be the name |
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242 (or a name) of the host that the connector server is running |
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243 on.</p> |
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244 |
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245 <p>In this <code>JMXServiceURL</code>, the first <code>rmi:</code> |
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246 specifies the RMI |
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247 connector, while the second <code>rmi:</code> specifies the RMI |
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248 registry.</p> |
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249 |
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250 <p>As another example, if the <code>JMXServiceURL</code> is: |
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251 |
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252 <pre> |
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253 <code>service:jmx:iiop://ignoredhost/jndi/ldap://dirhost:9999/cn=this,ou=that</code> |
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254 </pre> |
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255 |
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256 then the connector server will generate an |
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257 <code>RMIIIOPServerImpl</code> and store its stub using the JNDI |
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258 name |
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259 |
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260 <pre> |
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261 <code>ldap://dirhost:9999/cn=this,ou=that</code> |
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262 </pre> |
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263 |
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264 which means entry <code>cn=this,ou=that</code> in the LDAP |
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265 directory running on port 9999 of host <code>dirhost</code>.</p> |
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266 |
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267 <p>If the <code>JMXServiceURL</code> is: |
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268 |
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269 <pre> |
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270 <code>service:jmx:iiop://ignoredhost/jndi/cn=this,ou=that</code> |
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271 </pre> |
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272 |
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273 then the connector server will generate an |
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274 <code>RMIIIOPServerImpl</code> and store its stub using the JNDI |
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275 name |
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276 |
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277 <pre> |
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278 <code>cn=this,ou=that</code> |
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279 </pre> |
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280 |
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281 For this case to work, the JNDI API must have been configured |
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282 appropriately to supply the information about what directory to |
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283 use.</p> |
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284 |
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285 <p>In these examples, the host name <code>ignoredhost</code> is |
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286 not used by the connector server or its clients. It can be |
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287 omitted, for example:</p> |
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288 |
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289 <pre> |
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290 <code>service:jmx:iiop:///jndi/cn=this,ou=that</code> |
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291 </pre> |
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292 |
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293 <p>However, it is good practice to use the name of the host |
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294 where the connector server is running. This is often different |
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295 from the name of the directory host.</p> |
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296 |
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297 |
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298 <h4>Connector server attributes</h4> |
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299 |
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300 <p>When using the default JRMP transport, RMI socket factories can |
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301 be specified using the attributes |
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302 <code>jmx.remote.rmi.client.socket.factory</code> and |
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303 <code>jmx.remote.rmi.server.socket.factory</code> in the |
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304 <code>environment</code> given to the |
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305 <code>RMIConnectorServer</code> constructor. The values of these |
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306 attributes must be of type {@link |
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307 java.rmi.server.RMIClientSocketFactory} and {@link |
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308 java.rmi.server.RMIServerSocketFactory}, respectively. These |
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309 factories are used when creating the RMI objects associated with |
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310 the connector.</p> |
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311 |
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312 <h3>Creating an RMI connector client</h3> |
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313 |
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314 <p>An RMI connector client is usually constructed using {@link |
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315 javax.management.remote.JMXConnectorFactory}, with a |
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316 <code>JMXServiceURL</code> that has <code>rmi</code> or |
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317 <code>iiop</code> as its protocol.</p> |
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318 |
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319 <p>If the <code>JMXServiceURL</code> was generated by the server, |
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320 as described above under <a href="#servergen">"connector |
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321 addresses generated by the server"</a>, then the client will |
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322 need to obtain it directly or indirectly from the server. |
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323 Typically, the server makes the <code>JMXServiceURL</code> |
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324 available by storing it in a file or a lookup service.</p> |
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325 |
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326 <p>If the <code>JMXServiceURL</code> uses the directory syntax, as |
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327 described above under <a href="#directory">"connector addresses |
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328 based on directory entries"</a>, then the client may obtain it |
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329 as just explained, or client and server may both know the |
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330 appropriate directory entry to use. For example, if the |
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331 connector server for the Whatsit agent uses the entry |
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332 <code>whatsit-agent-connector</code> in the RMI registry on host |
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333 <code>myhost</code>, then client and server can both know |
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334 that the appropriate <code>JMXServiceURL</code> is:</p> |
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335 |
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336 <pre> |
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337 <code>service:jmx:rmi:///jndi/rmi://myhost/whatsit-agent-connector</code> |
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338 </pre> |
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339 |
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340 <p>If you have an RMI stub of type {@link |
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341 javax.management.remote.rmi.RMIServer RMIServer}, you can |
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342 construct an RMI connection directly by using the appropriate |
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343 constructor of {@link javax.management.remote.rmi.RMIConnector |
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344 RMIConnector}.</p> |
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345 |
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346 |
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347 <h3>Specifying an ORB for the RMI/IIOP connector</h3> |
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348 |
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349 <p>When using the IIOP transport, the client and server can |
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350 specify what ORB to use |
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351 with the attribute <code>java.naming.corba.orb</code>. |
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352 Connection to the ORB happens at {@link |
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353 javax.management.remote.rmi.RMIConnectorServer#start() start} time |
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354 for the connector server, and at {@link |
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355 javax.management.remote.rmi.RMIConnector#connect(java.util.Map) |
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356 connect} time for the connector client. |
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357 If the <code>java.naming.corba.orb</code> attribute is contained |
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358 in the environment Map, then its value (an {@link |
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359 org.omg.CORBA.ORB ORB}), is used to connect the IIOP Stubs. |
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360 Otherwise, a new org.omg.CORBA.ORB is created by calling {@link |
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361 org.omg.CORBA.ORB |
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362 org.omg.CORBA.ORB.init((String[])null,(Properties)null)}. A |
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363 later RMI connector client or server in the same JVM can reuse |
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364 this ORB, or it can create another one in the same way.</p> |
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365 |
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366 <p>If the <code>java.naming.corba.orb</code> attribute is |
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367 specified and does not point to an {@link org.omg.CORBA.ORB ORB}, |
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368 then an <code>{@link java.lang.IllegalArgumentException}</code> |
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369 will be thrown.</p> |
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370 |
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371 <p>The mechanism described here does not apply when the IIOP |
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372 Remote objects (Stubs or Servers) are created and connected to |
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373 an ORB manually before being passed to the RMIConnector and |
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374 RMIConnectorServer.</p> |
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375 |
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376 |
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377 <h3>Dynamic code downloading</h3> |
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378 |
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379 <p>If an RMI connector client or server receives from its peer an |
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380 instance of a class that it does not know, and if dynamic code |
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381 downloading is active for the RMI connection, then the class can |
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382 be downloaded from a codebase specified by the peer. The |
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383 article <a |
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384 href="{@docRoot}/../technotes/guides/rmi/codebase.html"><em>Dynamic |
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385 code downloading using Java RMI</em></a> explains this in more |
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386 detail.</p> |
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387 |
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388 |
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389 @see <a href="{@docRoot}/../technotes/guides/rmi/index.html"> |
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390 Java<sup><font size="-1">TM</font></sup> Remote Method |
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391 Invocation (RMI)</a> |
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392 |
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393 @see <a href="{@docRoot}/../technotes/guides/jndi/index.html"> |
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394 Java Naming and Directory Interface<sup><font |
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395 size="-1">TM</font></sup> (JNDI)</a> |
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396 |
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397 @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045, |
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398 section 6.8, "Base64 Content-Transfer-Encoding"</a> |
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399 |
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400 |
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401 @since 1.5 |
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402 |
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403 </body> |
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404 </html> |