1 <html> |
|
2 <head> |
|
3 <title>RMI connector</title> |
|
4 <!-- |
|
5 Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved. |
|
6 DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
|
7 |
|
8 This code is free software; you can redistribute it and/or modify it |
|
9 under the terms of the GNU General Public License version 2 only, as |
|
10 published by the Free Software Foundation. Oracle designates this |
|
11 particular file as subject to the "Classpath" exception as provided |
|
12 by Oracle in the LICENSE file that accompanied this code. |
|
13 |
|
14 This code is distributed in the hope that it will be useful, but WITHOUT |
|
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
|
16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
|
17 version 2 for more details (a copy is included in the LICENSE file that |
|
18 accompanied this code). |
|
19 |
|
20 You should have received a copy of the GNU General Public License version |
|
21 2 along with this work; if not, write to the Free Software Foundation, |
|
22 Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
|
23 |
|
24 Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
|
25 or visit www.oracle.com if you need additional information or have any |
|
26 questions. |
|
27 --> |
|
28 </head> |
|
29 <body bgcolor="white"> |
|
30 <p>The RMI connector is a connector for the JMX Remote API that |
|
31 uses RMI to transmit client requests to a remote MBean server. |
|
32 This package defines the classes that the user of an RMI |
|
33 connector needs to reference directly, for both the client and |
|
34 server sides. It also defines certain classes that the user |
|
35 will not usually reference directly, but that must be defined so |
|
36 that different implementations of the RMI connector can |
|
37 interoperate.</p> |
|
38 |
|
39 <p>The RMI connector supports the JRMP transport for RMI.</p> |
|
40 |
|
41 <p>Like most connectors in the JMX Remote API, an RMI connector |
|
42 usually has an address, which |
|
43 is a {@link javax.management.remote.JMXServiceURL |
|
44 JMXServiceURL}. The protocol part of this address is |
|
45 <code>rmi</code> for a connector that uses the default RMI |
|
46 transport (JRMP).</p> |
|
47 |
|
48 <p>There are two forms for RMI connector addresses:</p> |
|
49 |
|
50 <ul> |
|
51 <li> |
|
52 In the <em>JNDI form</em>, the URL indicates <em>where to find |
|
53 an RMI stub for the connector</em>. This RMI stub is a Java |
|
54 object of type {@link javax.management.remote.rmi.RMIServer |
|
55 RMIServer} that gives remote access to the connector server. |
|
56 With this address form, the RMI stub is obtained from an |
|
57 external directory entry included in the URL. An external |
|
58 directory is any directory recognized by {@link javax.naming |
|
59 JNDI}, typically the RMI registry, LDAP, or COS Naming. |
|
60 |
|
61 <li> |
|
62 In the <em>encoded form</em>, the URL directly includes the |
|
63 information needed to connect to the connector server. When |
|
64 using RMI/JRMP, the encoded form is the serialized RMI stub |
|
65 for the server object, encoded using BASE64 without embedded |
|
66 newlines. |
|
67 </ul> |
|
68 |
|
69 <p>Addresses are covered in more detail below.</p> |
|
70 |
|
71 |
|
72 <h3>Creating an RMI connector server</h3> |
|
73 |
|
74 <p>The usual way to create an RMI connector server is to supply an |
|
75 RMI connector address to the method {@link |
|
76 javax.management.remote.JMXConnectorServerFactory#newJMXConnectorServer |
|
77 JMXConnectorServerFactory.newJMXConnectorServer}. The MBean |
|
78 server to which the connector server is attached can be |
|
79 specified as a parameter to that method. Alternatively, the |
|
80 connector server can be registered as an MBean in that MBean |
|
81 server.</p> |
|
82 |
|
83 <p>An RMI connector server can also be created by constructing an |
|
84 instance of {@link |
|
85 javax.management.remote.rmi.RMIConnectorServer |
|
86 RMIConnectorServer}, explicitly or through the MBean server's |
|
87 <code>createMBean</code> method.</p> |
|
88 |
|
89 <h4>Choosing the RMI transport</h4> |
|
90 |
|
91 <p>You can choose the RMI transport by specifying |
|
92 <code>rmi</code> in the <code><em>protocol</em></code> part of the |
|
93 <code>serviceURL</code> when creating the connector server. You |
|
94 can also create specialized connector servers by instantiating |
|
95 an appropriate subclass of {@link |
|
96 javax.management.remote.rmi.RMIServerImpl RMIServerImpl} and |
|
97 supplying it to the <code>RMIConnectorServer</code> |
|
98 constructor.</p> |
|
99 |
|
100 |
|
101 <h4><a name="servergen">Connector addresses generated by the |
|
102 server</a></h4> |
|
103 |
|
104 <p>If the <code>serviceURL</code> you specify has an empty URL |
|
105 path (after the optional host and port), or if you do not |
|
106 specify a <code>serviceURL</code>, then the connector server |
|
107 will fabricate a new <code>JMXServiceURL</code> that clients can |
|
108 use to connect:</p> |
|
109 |
|
110 <ul> |
|
111 |
|
112 <li><p>If the <code>serviceURL</code> looks like:</p> |
|
113 |
|
114 <pre> |
|
115 <code>service:jmx:rmi://<em>host</em>:<em>port</em></code> |
|
116 </pre> |
|
117 |
|
118 <p>then the connector server will generate an {@link |
|
119 javax.management.remote.rmi.RMIJRMPServerImpl |
|
120 RMIJRMPServerImpl} and the returned <code>JMXServiceURL</code> |
|
121 looks like:</p> |
|
122 |
|
123 <pre> |
|
124 <code>service:jmx:rmi://<em>host</em>:<em>port</em>/stub/<em>XXXX</em></code> |
|
125 </pre> |
|
126 |
|
127 <p>where <code><em>XXXX</em></code> is the serialized form of the |
|
128 stub for the generated object, encoded in BASE64 without |
|
129 newlines.</p> |
|
130 |
|
131 <li><p>If there is no <code>serviceURL</code>, there must be a |
|
132 user-provided <code>RMIServerImpl</code>. The connector server |
|
133 will generate a <code>JMXServiceURL</code> using the <code>rmi</code> |
|
134 form.</p> |
|
135 |
|
136 </ul> |
|
137 |
|
138 <p>The <code><em>host</em></code> in a user-provided |
|
139 <code>serviceURL</code> is optional. If present, it is copied |
|
140 into the generated <code>JMXServiceURL</code> but otherwise |
|
141 ignored. If absent, the generated <code>JXMServiceURL</code> |
|
142 will have the local host name.</p> |
|
143 |
|
144 <p>The <code><em>port</em></code> in a user-provided |
|
145 <code>serviceURL</code> is also optional. If present, it is |
|
146 also copied into the generated <code>JMXServiceURL</code>; |
|
147 otherwise, the generated <code>JMXServiceURL</code> has no port. |
|
148 For an <code>serviceURL</code> using the <code>rmi</code> |
|
149 protocol, the <code><em>port</em></code>, if present, indicates |
|
150 what port the generated remote object should be exported on. It |
|
151 has no other effect.</p> |
|
152 |
|
153 <p>If the user provides an <code>RMIServerImpl</code> rather than a |
|
154 <code>JMXServiceURL</code>, then the generated |
|
155 <code>JMXServiceURL</code> will have the local host name in its |
|
156 <code><em>host</em></code> part and no |
|
157 <code><em>port</em></code>.</p> |
|
158 |
|
159 |
|
160 <h4><a name="directory">Connector addresses based on directory |
|
161 entries</a></h4> |
|
162 |
|
163 <p>As an alternative to the generated addresses just described, |
|
164 the <code>serviceURL</code> address supplied when creating a |
|
165 connector server can specify a <em>directory address</em> in |
|
166 which to store the provided or generated <code>RMIServer</code> |
|
167 stub. This directory address is then used by both client and |
|
168 server.</p> |
|
169 |
|
170 <p>In this case, the <code>serviceURL</code> has the following form:</p> |
|
171 |
|
172 <pre> |
|
173 <code>service:jmx:rmi://<em>host</em>:<em>port</em>/jndi/<em>jndi-name</em></code> |
|
174 </pre> |
|
175 |
|
176 <p>Here, <code><em>jndi-name</em></code> is a string that can be |
|
177 supplied to {@link javax.naming.InitialContext#bind |
|
178 javax.naming.InitialContext.bind}.</p> |
|
179 |
|
180 <p>As usual, the <code><em>host</em></code> and |
|
181 <code>:<em>port</em></code> can be omitted.</p> |
|
182 |
|
183 <p>The connector server will generate an |
|
184 <code>RMIServerImpl</code> based on the protocol |
|
185 (<code>rmi</code>) and the <code><em>port</em></code> if any. When |
|
186 the connector server is started, it will derive a stub from this |
|
187 object using its {@link |
|
188 javax.management.remote.rmi.RMIServerImpl#toStub toStub} method |
|
189 and store the object using the given |
|
190 <code><em>jndi-name</em></code>. The properties defined by the |
|
191 JNDI API are consulted as usual.</p> |
|
192 |
|
193 <p>For example, if the <code>JMXServiceURL</code> is: |
|
194 |
|
195 <pre> |
|
196 <code>service:jmx:rmi://ignoredhost/jndi/rmi://myhost/myname</code> |
|
197 </pre> |
|
198 |
|
199 then the connector server will generate an |
|
200 <code>RMIJRMPServerImpl</code> and store its stub using the JNDI |
|
201 name |
|
202 |
|
203 <pre> |
|
204 <code>rmi://myhost/myname</code> |
|
205 </pre> |
|
206 |
|
207 which means entry <code>myname</code> in the RMI registry |
|
208 running on the default port of host <code>myhost</code>. Note |
|
209 that the RMI registry only allows registration from the local |
|
210 host. So, in this case, <code>myhost</code> must be the name |
|
211 (or a name) of the host that the connector server is running |
|
212 on. |
|
213 |
|
214 <p>In this <code>JMXServiceURL</code>, the first <code>rmi:</code> |
|
215 specifies the RMI |
|
216 connector, while the second <code>rmi:</code> specifies the RMI |
|
217 registry. |
|
218 |
|
219 <p>As another example, if the <code>JMXServiceURL</code> is: |
|
220 |
|
221 <pre> |
|
222 <code>service:jmx:rmi://ignoredhost/jndi/ldap://dirhost:9999/cn=this,ou=that</code> |
|
223 </pre> |
|
224 |
|
225 then the connector server will generate an |
|
226 <code>RMIJRMPServerImpl</code> and store its stub using the JNDI |
|
227 name |
|
228 |
|
229 <pre> |
|
230 <code>ldap://dirhost:9999/cn=this,ou=that</code> |
|
231 </pre> |
|
232 |
|
233 which means entry <code>cn=this,ou=that</code> in the LDAP |
|
234 directory running on port 9999 of host <code>dirhost</code>. |
|
235 |
|
236 <p>If the <code>JMXServiceURL</code> is: |
|
237 |
|
238 <pre> |
|
239 <code>service:jmx:rmi://ignoredhost/jndi/cn=this,ou=that</code> |
|
240 </pre> |
|
241 |
|
242 then the connector server will generate an |
|
243 <code>RMIJRMPServerImpl</code> and store its stub using the JNDI |
|
244 name |
|
245 |
|
246 <pre> |
|
247 <code>cn=this,ou=that</code> |
|
248 </pre> |
|
249 |
|
250 For this case to work, the JNDI API must have been configured |
|
251 appropriately to supply the information about what directory to |
|
252 use. |
|
253 |
|
254 <p>In these examples, the host name <code>ignoredhost</code> is |
|
255 not used by the connector server or its clients. It can be |
|
256 omitted, for example:</p> |
|
257 |
|
258 <pre> |
|
259 <code>service:jmx:rmi:///jndi/cn=this,ou=that</code> |
|
260 </pre> |
|
261 |
|
262 <p>However, it is good practice to use the name of the host |
|
263 where the connector server is running. This is often different |
|
264 from the name of the directory host.</p> |
|
265 |
|
266 |
|
267 <h4>Connector server attributes</h4> |
|
268 |
|
269 <p>When using the default JRMP transport, RMI socket factories can |
|
270 be specified using the attributes |
|
271 <code>jmx.remote.rmi.client.socket.factory</code> and |
|
272 <code>jmx.remote.rmi.server.socket.factory</code> in the |
|
273 <code>environment</code> given to the |
|
274 <code>RMIConnectorServer</code> constructor. The values of these |
|
275 attributes must be of type {@link |
|
276 java.rmi.server.RMIClientSocketFactory} and {@link |
|
277 java.rmi.server.RMIServerSocketFactory}, respectively. These |
|
278 factories are used when creating the RMI objects associated with |
|
279 the connector.</p> |
|
280 |
|
281 <h3>Creating an RMI connector client</h3> |
|
282 |
|
283 <p>An RMI connector client is usually constructed using {@link |
|
284 javax.management.remote.JMXConnectorFactory}, with a |
|
285 <code>JMXServiceURL</code> that has <code>rmi</code> as its protocol.</p> |
|
286 |
|
287 <p>If the <code>JMXServiceURL</code> was generated by the server, |
|
288 as described above under <a href="#servergen">"connector |
|
289 addresses generated by the server"</a>, then the client will |
|
290 need to obtain it directly or indirectly from the server. |
|
291 Typically, the server makes the <code>JMXServiceURL</code> |
|
292 available by storing it in a file or a lookup service.</p> |
|
293 |
|
294 <p>If the <code>JMXServiceURL</code> uses the directory syntax, as |
|
295 described above under <a href="#directory">"connector addresses |
|
296 based on directory entries"</a>, then the client may obtain it |
|
297 as just explained, or client and server may both know the |
|
298 appropriate directory entry to use. For example, if the |
|
299 connector server for the Whatsit agent uses the entry |
|
300 <code>whatsit-agent-connector</code> in the RMI registry on host |
|
301 <code>myhost</code>, then client and server can both know |
|
302 that the appropriate <code>JMXServiceURL</code> is:</p> |
|
303 |
|
304 <pre> |
|
305 <code>service:jmx:rmi:///jndi/rmi://myhost/whatsit-agent-connector</code> |
|
306 </pre> |
|
307 |
|
308 <p>If you have an RMI stub of type {@link |
|
309 javax.management.remote.rmi.RMIServer RMIServer}, you can |
|
310 construct an RMI connection directly by using the appropriate |
|
311 constructor of {@link javax.management.remote.rmi.RMIConnector |
|
312 RMIConnector}.</p> |
|
313 |
|
314 <h3>Dynamic code downloading</h3> |
|
315 |
|
316 <p>If an RMI connector client or server receives from its peer an |
|
317 instance of a class that it does not know, and if dynamic code |
|
318 downloading is active for the RMI connection, then the class can |
|
319 be downloaded from a codebase specified by the peer. The |
|
320 article <a |
|
321 href="{@docRoot}/../technotes/guides/rmi/codebase.html"><em>Dynamic |
|
322 code downloading using Java RMI</em></a> explains this in more |
|
323 detail.</p> |
|
324 |
|
325 |
|
326 @see <a href="{@docRoot}/../technotes/guides/rmi/index.html"> |
|
327 Java™ Remote Method |
|
328 Invocation (RMI)</a> |
|
329 |
|
330 @see <a href="{@docRoot}/../technotes/guides/jndi/index.html"> |
|
331 Java Naming and Directory Interface™ (JNDI)</a> |
|
332 |
|
333 @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045, |
|
334 section 6.8, "Base64 Content-Transfer-Encoding"</a> |
|
335 |
|
336 |
|
337 @since 1.5 |
|
338 |
|
339 </body> |
|
340 </html> |
|