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src/share/classes/org/omg/PortableServer/package.html
Thu, 17 Jun 2010 16:27:56 -0700
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- mikejwre
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- Thu, 17 Jun 2010 16:27:56 -0700
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Added tag jdk7-b98 for changeset 3b99409057e4
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34 Provides classes and interfaces for making the server side of your applications
35 portable across multivendor ORBs.
37 <P>In Java, Portable Object Adaptor (POA)-based Dynamic Skeleton Interface (DSI)
38 servants inherit from the standard <TT>DynamicImplementation</TT> class, which
39 inherits from the <TT>Servant</TT> class. The native <TT>Servant</TT> type is
40 defined by the <TT>PortableServer</TT> module for the POA. In Java, the
41 <TT>Servant</TT> type is mapped to the Java
42 <TT>org.omg.PortableServer.Servant</TT> class.
43 It serves as the base class for all POA servant
44 implementations and provides a number of methods that may
45 be invoked by the application programmer, as well as methods
46 which are invoked by the POA itself and may be overridden by
47 the user to control aspects of servant behavior.
49 <H2>Package Specification</H2>
51 <P>For a precise list of supported sections of official OMG specifications with which
52 the Java[tm] Platform, Standard Edition 6 complies, see <A
53 HREF="../CORBA/doc-files/compliance.html">Official Specifications for CORBA
54 support in Java[tm] SE 6</A>.
55 <p>
57 <H2>POA-related Interfaces</H2>
59 <P>The <TT>PortableServer</TT> module defines the following POA-related interfaces:
60 <P>
61 <UL>
62 <LI><TT>POA</TT>
63 <LI><TT>POAManager</TT>
64 <LI><TT>ServantManager</TT>
65 <LI><TT>ServantActivator</TT>
66 <LI><TT>ServantLocator</TT>
67 <LI><TT>AdapterActivator</TT>
68 <LI><TT>ThreadPolicy</TT>
69 <LI><TT>LifespanPolicy</TT>
70 <LI><TT>IdUniquenessPolicy</TT>
71 <LI><TT>IdAssignmentPolicy</TT>
72 <LI><TT>ImplicitActivationPolicy</TT>
73 <LI><TT>ServantRetentionPolicy</TT>
74 <LI><TT>RequestProcessingPolicy</TT>
75 <LI><TT>Current</TT>
76 </UL>
78 <P>In addition, the POA defines the <TT>Servant</TT> native type.
80 <H3>Operations classes</H3>
82 <P>Each of the interfaces listed above has an associated <code>Operations</code> interface. The <code>Operations</code> interface is generated by the <code>idlj</code> compiler and contains the method signatures for methods defined in its associated interface. The <code>Operations</code> interface can be accessed by both the client and the server, while its associated interface can only be called by the client.
84 <H3>Value Classes</H3>
86 Classes ending in the suffix <code>PolicyValue</code> provide the values used for the <code>create_POA</code> call, which sets the policy for the POA. See the <a href="#sampleserver">sample code</a> below for a demonstration. <code>PolicyValue</code> files include the following:
87 <P>
88 <UL>
89 <LI><code>IdAssignmentPolicyValue</code>
90 <LI><code>IdUniquenessPolicyValue</code>
91 <LI><code>ImplicitActivationPolicyValue</code>
92 <LI><code>LifespanPolicyValue</code>
93 <LI><code>RequestProcessingPolicyValue</code>
94 <LI><code>ServantRetentionPolicyValue</code>
95 <LI><code>ThreadPolicyValue</code>
96 </UL>
98 <H3>Helper Classes</H3>
100 <P>Helper classes, which are generated for all user-defined types in an OMG IDL
101 interface, supply static methods needed to manipulate those types. There is only one method in a helper class that an application programmer uses: the <code>narrow</code> method. Only Java interfaces mapped from IDL interfaces will have a helper class that includes a <code>narrow</code> method, so in the <code>PortableServer</code> package, only the following classes have a <code>narrow</code> method:
102 <P>
103 <UL>
104 <LI><code>ForwardRequestHelper</code>
105 <LI><code>ServantActivatorHelper</code>
106 <LI><code>ServantLocatorHelper</code>
107 </UL>
109 <H3>POA Classes</H3>
111 <P>POA classes are used to implement the <code>ServantActivator</code> or <code>ServantLocator</code>.
113 <H3>Exceptions</H3>
115 <P>The <code>ForwardRequest</code> exception indicates to the ORB
116 that it is responsible for delivering the current request and subsequent <code>ForwardRequest</code> requests to the object denoted in the
117 <code>forward_reference</code> member of the exception.
119 <H3>Interfaces Implemented by the Application Programmer</H3>
121 <P>Most of what <code>PortableServer</code> does is transparent to the user. The result is that programmers will use only a few of the interfaces mentioned above. The remaining interfaces will be provided by the ORB implementation. The interfaces of interest to application programmers are the following:
122 <P>
123 <ul>
124 <LI><code>AdapterActivator</code>
125 <P>Adapter activators are associated with POAs. An adapter activator supplies a POA with the ability to create child POAs on demand, as a side-effect of receiving a request that names the child POA (or one of its children), or when <code>find_POA</code> is called with an activate parameter value of <code>TRUE</code>. An application server that creates all its needed POAs at the beginning of execution does not need to use or provide an adapter activator; it is necessary only for the case in which POAs need to be created during request processing.
126 <P>
127 <LI><code>ServantLocator</code>
128 <P>When the POA has the <code>NON_RETAIN</code> policy, it uses servant managers that are <code>ServantLocator</code>s.
129 <P>
130 <LI><code>ServantActivator</code>
131 <P>When the POA has the <code>RETAIN</code> policy, it uses servant managers that are <code>ServantActivator</code>s.
132 </ul>
135 <H2>Package <TT>org.omg.PortableServer.ServantLocatorPackage</TT></H2>
137 <P>This package supplies a <TT>CookieHolder</TT> class for passing
138 the <TT>Cookie</TT> type as an <code>out</code> parameter. The <code>CookieHolder</code> class
139 follows exactly the same pattern as the other holder classes for basic types.
141 <H2>Related Documentation</H2>
143 <P>For an overview of Java IDL, please see:
144 <P>
145 <LI><A HREF="../../../../technotes/guides/idl/index.html">Java IDL home page</A>.
147 <H2>Example Code</H2>
148 <a name="sampleserver"></a>
149 <H3>Example Server Code</H3>
150 <P>
151 <PRE>
152 import javax.naming.InitialContext;
153 import javax.naming.Context;
154 import javax.rmi.PortableRemoteObject ;
155 import com.sun.corba.se.impl.poa.POAORB;
156 import org.omg.PortableServer.*;
157 import java.util.*;
158 import org.omg.CORBA.*;
159 import javax.rmi.CORBA.Stub;
160 import javax.rmi.CORBA.Util;
164 public class HelloServer {
165 public HelloServer(String[] args) {
166 try {
167 Properties p = System.getProperties();
168 // p.put("org.omg.CORBA.ORBClass", "com.sun.corba.ee.internal.POA.POAORB");
169 ORB orb = ORB.init( args, p );
171 POA rootPOA = (POA)orb.resolve_initial_references("RootPOA");
172 <strong>
173 Policy[] tpolicy = new Policy[3];
174 tpolicy[0] = rootPOA.create_lifespan_policy(
175 LifespanPolicyValue.TRANSIENT );
176 tpolicy[1] = rootPOA.create_request_processing_policy(
177 RequestProcessingPolicyValue.USE_ACTIVE_OBJECT_MAP_ONLY );
178 tpolicy[2] = rootPOA.create_servant_retention_policy(
179 ServantRetentionPolicyValue.RETAIN);
180 POA tpoa = rootPOA.create_POA("MyTransientPOA", null, tpolicy);
181 </strong>
183 String ObjectId = "MyObjectId";
184 byte[] oid = ObjectId.getBytes();
186 org.omg.CORBA.Object obj = tpoa.create_reference_with_id(oid,
187 new _HelloImpl_Tie()._all_interfaces(tpoa, oid)[0]);
188 HelloInterface helloRef = (HelloInterface)PortableRemoteObject.narrow(
189 obj, HelloInterface.class );
191 Context initialNamingContext = new InitialContext();
192 initialNamingContext.rebind("HelloService", helloRef);
193 System.out.println("Hello Server: Ready...");
194 orb.run();
195 } catch (Exception e) {
196 System.out.println("Trouble: " + e);
197 e.printStackTrace();
198 }
199 }
202 public static void main(String args[]) {
203 new HelloServer( args );
204 }
205 }
208 </PRE>
212 <P>
215 @since 1.4
216 <br>
217 @serial exclude
218 </body>
219 </html>
