com.sun.corba.se.spi.oa

Interface ObjectAdapter

All Known Implementing Classes:

ObjectAdapterBase, POAImpl

public interface ObjectAdapter

ObjectAdapter represents the abstract model of an object adapter that was introduced by ORT. This means that all object adapters must:

• Have an ORB
• Have a name
• Have an adapter manager (represented by an ID)
• Have an adapter template
• Support getting and setting their ObjectReferenceFactory
• Provide access to their current state
• Support adding components to their profiles expressed in the adapter template

Other requirements:

• All object adapters must invoke ORB.AdapterCreated when they are created.
• All adapter managers must invoke ORB.AdapterManagerStateChanged when their state changes, mapping the internal state to an ORT state.
• AdapterStateChanged must be invoked (from somewhere) whenever an adapter state changes that is not due to an adapter manager state change.

Object adapters must also provide mechanisms for:

• Managing object reference lifecycle
• Controlling how servants are associated with object references
• Manage the state of the adapter, if the adapter desires to implement such mechanisms

Such mechanisms are all object adapter specific, and so we do not attempt to create general APIs for these functions here. The object adapter itself must provide these APIs directly to the user, and they do not affect the rest of the ORB. This interface basically makes it possible to plug any object adapter into the ORB and have the OA work propertly with portable interceptors, and also have requests dispatched properly to the object adapter.

The basic function of an ObjectAdapter is to map object IDs to servants and to support the dispatch operation of the subcontract, which dispatches requests to servants. This is the purpose of the getInvocationServant method. In addition, ObjectAdapters must be able to change state gracefully in the presence of executing methods. This requires the use of the enter/exit methods. Finally, ObjectAdapters often require access to information about requests. This is accomodated through the OAInvocationInfo class and the thread local stack maintained by push/pop/peekInvocationInfo on the ORB.

To be useful, this dispatch cycle must be extremely efficient. There are several scenarios that matter:

1. A remote invocation, where the dispatch is handled in the server subcontract.
2. A local invocation, where the dispatch is handled in the client subcontract.
3. A cached local invocation, where the servant is cached when the IOR is established for the client subcontract, and the dispatch is handled in the client subcontract to the cached subcontract.

Each of these 3 cases is handled a bit differently. On each request, assume as known ObjectId and ObjectAdapterId, which can be obtained from the object key. The ObjectAdaptorFactory is available in the subcontract registry, where it is registered under the subcontract ID. The Subcontract ID is also available in the object key.

1. The remote pattern:
   1. oa = oaf.find( oaid )
   2. oa.enter()
   3. info = oa.makeInvocationInfo( oid )
   4. info.setOperation( operation )
   5. push info
   6. oa.getInvocationServant( info )
   7. sreq.setExecuteReturnServantInResponseConstructor( true )
   8. dispatch to servant
   9. oa.returnServant()
   10. oa.exit()
   11. pop info
   REVISIT: Is this the required order for exit/pop? Cna they be nested instead? Note that getInvocationServant and returnServant may throw exceptions. In such cases, returnServant, exit, and pop must be called in the correct order.
   1. The local pattern:
      1. oa = oaf.find( oaid )
      2. oa.enter()
      3. info = oa.makeInvocationInfo( oid )
      4. info.setOperation( operation )
      5. push info
      6. oa.getInvocationServant( info )
      7. dispatch to servant
      8. oa.returnServant()
      9. oa.exit()
      10. pop info
      This is the same as the remote case, except that setExecuteReturnServantInResponseConstructor is not needed (or possible, since there is no server request).
      1. The fast local pattern: When delegate is constructed, first extract ObjectKey from IOR in delegate, then get ObjectId, ObjectAdapterId, and ObjectAdapterFactory (oaf). Then:
         1. oa = oaf.find( oaid )
         2. info = oa.makeInvocationInfo( oid ) (note: no operation!)
         3. push info (needed for the correct functioning of getInvocationServant)
         4. oa.getInvocationServant( info )
         5. pop info
         The info instance (which includes the Servant) is cached in the client subcontract.

         Then, on each invocation:

         1. newinfo = copy of info (clone)
         2. info.setOperation( operation )
         3. push newinfo
         4. oa.enter()
         5. dispatch to servant
         6. oa.returnServant()
         // XXX This is probably wrong: remove it.
         7. oa.exit()
         8. pop info
      XXX fast local should not call returnServant: what is correct here?

Method Summary

Methods

Modifier and Type	Method and Description
void	enter() enter must be called before each request is invoked on a servant.
void	exit() exit must be called after each request has been completed.
ObjectReferenceTemplate	getAdapterTemplate()
ObjectReferenceFactory	getCurrentFactory()
Policy	getEffectivePolicy(int type)
String[]	getInterfaces(Object servant, byte[] objectId) Return the most derived interface for the given servant and objectId.
void	getInvocationServant(OAInvocationInfo info) Get the servant for the request given by the parameters.
IORTemplate	getIORTemplate() Returns the IOR template of this adapter.
Object	getLocalServant(byte[] objectId) Get the servant corresponding to the given objectId, if this is supported.
int	getManagerId() Return the ID of the AdapterManager for this object adapter.
ORB	getORB() Returns the ORB associated with this adapter.
short	getState() Return the current state of this object adapter (see org.omg.PortableInterceptors for states.
OAInvocationInfo	makeInvocationInfo(byte[] objectId) Create an instance of InvocationInfo that is appropriate for this Object adapter.
void	returnServant() Must be called every time getInvocationServant is called after the request has completed.
void	setCurrentFactory(ObjectReferenceFactory factory) Change the current factory.

Method Detail

getORB

ORB getORB()

Returns the ORB associated with this adapter.

getEffectivePolicy

Policy getEffectivePolicy(int type)

getIORTemplate

IORTemplate getIORTemplate()

Returns the IOR template of this adapter. The profiles in this template may be updated only during the AdapterCreated call. After that call completes, the IOR template must be made immutable. Note that the server ID, ORB ID, and adapter name are all available from the IOR template.

getManagerId

int getManagerId()

Return the ID of the AdapterManager for this object adapter.

getState

short getState()

Return the current state of this object adapter (see org.omg.PortableInterceptors for states.

getAdapterTemplate

ObjectReferenceTemplate getAdapterTemplate()

getCurrentFactory

ObjectReferenceFactory getCurrentFactory()

setCurrentFactory

void setCurrentFactory(ObjectReferenceFactory factory)

Change the current factory. This may only be called during the AdapterCreated call.

getLocalServant

Object getLocalServant(byte[] objectId)

Get the servant corresponding to the given objectId, if this is supported. This method is only used for models where the servant is an ObjectImpl, which allows the servant to be used directly as the stub. This allows an object reference to be replaced by its servant when it is unmarshalled locally. Such objects are not ORB mediated.

getInvocationServant

void getInvocationServant(OAInvocationInfo info)

Get the servant for the request given by the parameters. info must contain a valid objectId in this call. The servant is set in the InvocationInfo argument that is passed into this call.

Parameters:

info - is the InvocationInfo object for the object reference

Throws:

ForwardException - (a runtime exception) is thrown if the request is to be handled by a different object reference.

enter

void enter()
           throws OADestroyed

enter must be called before each request is invoked on a servant.

Throws:

OADestroyed - is thrown when an OA has been destroyed, which requires a retry in the case where an AdapterActivator is present.

exit

void exit()

exit must be called after each request has been completed. If enter is called, there must always be a corresponding exit.

returnServant

void returnServant()

Must be called every time getInvocationServant is called after the request has completed.

makeInvocationInfo

OAInvocationInfo makeInvocationInfo(byte[] objectId)

Create an instance of InvocationInfo that is appropriate for this Object adapter.

getInterfaces

String[] getInterfaces(Object servant,
                     byte[] objectId)

Return the most derived interface for the given servant and objectId.