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  33 <body>
  34 Provides classes and interfaces for making the server side of your applications 
  35 portable across multivendor ORBs.
  36 
  37 <P>In Java, Portable Object Adaptor (POA)-based Dynamic Skeleton Interface (DSI)
  38 servants inherit from the  standard <code>DynamicImplementation</code> class, which
  39 inherits from the <code>Servant</code> class. The native <code>Servant</code> type is
  40 defined by the <code>PortableServer</code> module for the POA. In Java, the
  41   <code>Servant</code> type is mapped to the Java
  42   <code>org.omg.PortableServer.Servant</code> 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.
  48   
  49 <H2>Package Specification</H2>
  50  
  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 
  56 <H2>POA-related Interfaces</H2>
  57 
  58 <P>The <code>PortableServer</code> module defines the following POA-related interfaces:
  59 <UL>
  60         <LI><code>POA</code>
  61         <LI><code>POAManager</code>
  62         <LI><code>ServantManager</code>
  63         <LI><code>ServantActivator</code>
  64         <LI><code>ServantLocator</code>
  65         <LI><code>AdapterActivator</code>
  66         <LI><code>ThreadPolicy</code>
  67         <LI><code>LifespanPolicy</code>
  68         <LI><code>IdUniquenessPolicy</code>
  69         <LI><code>IdAssignmentPolicy</code>
  70         <LI><code>ImplicitActivationPolicy</code>
  71         <LI><code>ServantRetentionPolicy</code>
  72         <LI><code>RequestProcessingPolicy</code>
  73         <LI><code>Current</code>
  74 </UL>
  75 
  76 <P>In addition, the POA defines the <code>Servant</code> native type.
  77 
  78 <H3>Operations classes</H3>
  79 
  80 <P>Each of the interfaces listed above has an associated <code>Operations</code> interface.
  81 The <code>Operations</code> interface is generated by the <code>idlj</code> compiler and
  82 contains the method signatures for methods defined in its associated interface.
  83 The <code>Operations</code> interface can be accessed by both the client and the server,
  84 while its associated interface can only be called by the client.
  85 
  86 <H3>Value Classes</H3>
  87 
  88 Classes ending in the suffix <code>PolicyValue</code> provide the values used
  89 for the <code>create_POA</code> call, which sets the policy for the POA. See
  90 the <a href="#sampleserver">sample code</a> below for a demonstration.
  91 <code>PolicyValue</code> files include the following:
  92 <UL>
  93 <LI><code>IdAssignmentPolicyValue</code>
  94 <LI><code>IdUniquenessPolicyValue</code>
  95 <LI><code>ImplicitActivationPolicyValue</code>
  96 <LI><code>LifespanPolicyValue</code>
  97 <LI><code>RequestProcessingPolicyValue</code>
  98 <LI><code>ServantRetentionPolicyValue</code>
  99 <LI><code>ThreadPolicyValue</code>
 100 </UL>
 101 
 102 <H3>Helper Classes</H3>
 103 
 104 <P>Helper classes, which are generated for all user-defined types in an OMG IDL
 105 interface, supply static methods needed to manipulate those types.
 106 There is only one method in a helper class that an application programmer uses:
 107 the  <code>narrow</code> method.  Only Java interfaces mapped from IDL interfaces
 108 will have a helper class that includes a <code>narrow</code> method, so in
 109 the <code>PortableServer</code> package, only the following classes have a <code>narrow</code> method:
 110 <UL>
 111 <LI><code>ForwardRequestHelper</code>
 112 <LI><code>ServantActivatorHelper</code>
 113 <LI><code>ServantLocatorHelper</code>
 114 </UL>
 115 
 116 <H3>POA Classes</H3>
 117 
 118 <P>POA classes are used to implement the <code>ServantActivator</code> or <code>ServantLocator</code>.
 119 
 120 <H3>Exceptions</H3>
 121 
 122 <P>The <code>ForwardRequest</code> exception indicates to the ORB
 123 that it is responsible for delivering the current request and
 124 subsequent <code>ForwardRequest</code> requests to the object denoted in the
 125 <code>forward_reference</code> member of the exception.
 126 
 127 <H3>Interfaces Implemented by the Application Programmer</H3>
 128 
 129 <P>Most of what <code>PortableServer</code> does is transparent to the user.
 130 The result is that programmers will use only a few of the interfaces mentioned above.
 131 The remaining interfaces will be provided by the ORB implementation.
 132 The interfaces of interest to application programmers are the following:
 133 <ul>
 134   <LI><code>AdapterActivator</code>
 135   <P>Adapter activators are associated with POAs.
 136   An adapter activator supplies a POA with the ability to create child POAs on demand,
 137   as a side-effect of receiving a request that names the child POA (or one of its children),
 138   or when <code>find_POA</code> is called with an activate parameter value of <code>TRUE</code>.
 139   An application server that creates all its needed POAs at the beginning of execution
 140   does not need to use or provide an adapter activator; it is necessary
 141   only for the case in which POAs need to be created during request processing.
 142   <LI><code>ServantLocator</code>
 143   <P>When the POA has the <code>NON_RETAIN</code> policy,
 144   it uses servant managers that are <code>ServantLocator</code>s.
 145   <LI><code>ServantActivator</code>
 146   <P>When the POA has the <code>RETAIN</code> policy,
 147   it uses servant managers that are <code>ServantActivator</code>s.
 148 </ul>
 149 
 150 
 151 <H2>Package <code>org.omg.PortableServer.ServantLocatorPackage</code></H2>
 152 
 153 <P>This package supplies a <code>CookieHolder</code> class for passing
 154 the <code>Cookie</code> type as an <code>out</code> parameter. The <code>CookieHolder</code> class
 155 follows exactly the same pattern as the other holder classes for basic types.
 156 
 157 <H2>Related Documentation</H2>
 158 
 159 <P>For an overview of Java IDL, please see:
 160 {@extLink idl_guides Java&nbsp;IDL home page}.
 161 
 162 <H2>Example Code</H2>
 163 <a id="sampleserver"></a>
 164 <H3>Example Server Code</H3>
 165 <PRE>
 166 import javax.naming.InitialContext;
 167 import javax.naming.Context;
 168 import javax.rmi.PortableRemoteObject ;
 169 import com.sun.corba.se.impl.poa.POAORB;
 170 import org.omg.PortableServer.*;
 171 import java.util.*;
 172 import org.omg.CORBA.*;
 173 import javax.rmi.CORBA.Stub;
 174 import javax.rmi.CORBA.Util;
 175 
 176 
 177 
 178 public class HelloServer {
 179     public HelloServer(String[] args) {
 180         try {
 181             Properties p = System.getProperties();
 182          //   p.put("org.omg.CORBA.ORBClass", "com.sun.corba.ee.internal.POA.POAORB");
 183             ORB orb = ORB.init( args, p );
 184 
 185             POA rootPOA = (POA)orb.resolve_initial_references("RootPOA");
 186 <strong>
 187             Policy[] tpolicy = new Policy[3];
 188             tpolicy[0] = rootPOA.create_lifespan_policy(
 189                 LifespanPolicyValue.TRANSIENT );
 190             tpolicy[1] = rootPOA.create_request_processing_policy(
 191                 RequestProcessingPolicyValue.USE_ACTIVE_OBJECT_MAP_ONLY );
 192             tpolicy[2] = rootPOA.create_servant_retention_policy(
 193                 ServantRetentionPolicyValue.RETAIN);
 194             POA tpoa = rootPOA.create_POA("MyTransientPOA", null, tpolicy);
 195 </strong>
 196 
 197             String  ObjectId = "MyObjectId";
 198             byte[] oid = ObjectId.getBytes();
 199 
 200             org.omg.CORBA.Object obj = tpoa.create_reference_with_id(oid,
 201                 new _HelloImpl_Tie()._all_interfaces(tpoa, oid)[0]);
 202             HelloInterface helloRef = (HelloInterface)PortableRemoteObject.narrow(
 203                 obj, HelloInterface.class );
 204 
 205             Context initialNamingContext = new InitialContext();
 206             initialNamingContext.rebind("HelloService", helloRef);
 207             System.out.println("Hello Server: Ready...");
 208             orb.run();
 209          } catch (Exception e) {
 210             System.out.println("Trouble: " + e);
 211             e.printStackTrace();
 212          } 
 213      }
 214 
 215 
 216      public static void main(String args[]) {
 217          new HelloServer( args );
 218      }
 219 }
 220 
 221 
 222 </PRE>
 223 
 224 
 225 
 226 @since 1.4
 227 <br>
 228 @serial exclude
 229 </body>
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