E.9 Portable Object Adaptor

Transkript

1 More complicated activation schemes interface Persistent references E CA Object Life Cycle State diagram for life cycle Object Exists Servant Etherialized/ Object Deactivated Object Non-existent Reference Creation "Destruction" Object Non-existent Object Activation Object Deactivation Servant Incarnated/ Object Activated OA has to create servant and activate object when call arrives E.137

2 2 Operation operation controlled by Manager Manager states Manager::activate Active Manager::deactivate Manager::discard_requests ::create_ Holding Manager::hold_requests Manager::deactivate Inactive ::destroy Manager::hold_requests Manager::activate Discarding Manager::deactivate Manager::discard_requests One Manager for multiple s possible PIDL interface Manager E Creation IDL interface: module PortableServer { interface Manager; exception AdapterAlreadyExists { exception InvalidPolicy { unsigned short index; interface { create_(in string adapter_name, in Manager manager, in CA::PolicyList policies ) raises(adapteralreadyexists, InvalidPolicy);... Policies influence operation Root already exists in org.omg.ca.object o = orb.resolve_initial_references( "Root" ); org.omg.portableserver. root_poa = org.omg.portableserver.helper.narrow( o ); E.139

3 3 Creation Hierarchy of s Server Process Root manages Manager "My" creates "Foo" manages Manager manages creates "Baz" E Policies IDL: module CA { typedef unsigned long PolicyType; interface Policy { readonly attribute PolicyType policy_type; Policy copy(); void destroy(); typedef sequence<policy> PolicyList; Locality-constrained objects E.141

4 5 CA Object Life Span Policy IDL: module PortableServer { enum LifespanPolicyValue { TRANSIENT, PERSISTENT interface LifespanPolicy : CA::Policy { readonly attribute LifespanPolicyValue value; Single can either support persistent or transient objects, not both Persistent objects and must keep track of these objects Additional information for re-activation is stored Default Value: TRANSIENT E Object Identifiers Objects are identified via object references Object Reference Type Profile 1, e.g. IIOP Profile 2 Profile... Profile Contact Information, e.g. IP-Address/TCP-Port Object Key Object Key Path, e.g. "/Foo/Baz" Object Identifier... Object Identifier M y O b j e c t Object IDs either chosen by: the (SYSTEM_ID) the application (USER_ID), e.g. when objects are mapped to a database E.143

5 6 Object Identifiers IDL: module PortableServer { enum IdAssignmentPolicyValue { SYSTEM_ID, USER_ID interface IdAssignmentPolicy : CA::Policy { readonly attribute IdAssignmentPolicyValue value; Default Value: SYSTEM_ID E Mapping Objects to Servants Relation between Object IDs and Servants IDL: module PortableServer { enum IdUniquenessPolicyValue { UNIQUE_ID, MULTIPLE_ID interface IdUniquenessPolicy : CA::Policy { readonly attribute IdUniquenessPolicyValue value; UNIQUE_ID: One-to-one relation between objects and servants MULTIPLE_ID: There may be several CA objects (and therefore several Object IDs) that are implemented by the same Servant Default Value: UNIQUE_ID E.145

6 8 Implicit Activation Activation via some special Skeleton method (in Java _this()) IDL: module PortableServer { enum ImplicitActivationPolicyValue { IMPLICIT_ACTIVATION, NO_IMPLICIT_ACTIVATION interface ImplicitActivationPolicy : CA::Policy { readonly attribute ImplicitActivationPolicyValue value; Default Value: NO_IMPLICIT_ACTIVATION Exception: Root has IMPLICIT_ACTIVATION E Matching Requests to Servants can store active Servants in an Active Object Map Servants Object Identifier Object ID Object Reference Object ID Object ID Object ID Object ID Object ID Object ID Object ID Object ID Object ID Servant Pointer Servant Pointer Servant Pointer Servant Pointer Servant Pointer Servant Pointer Servant Pointer Servant Pointer Servant Pointer Active Object Map Only objects that are registered in Active Object Map exist (USE_ACTIVE_OBJECT_MAP_ONLY) throws CA::OBJECT_NOT_EXIST otherwise E.147

7 9 Matching Requests to Servants For dynamic activation application supplies a Servant Manager to the Servant Manager is contacted if Object ID is not found in Active Object Map Servant Manager may either return a Servant for the object or throw a CA::OBJECT_NOT_EXIST Mode is USE_SERVANT_MANAGER The application supplies a Default Servant there is no Active Object Map All requests are sent to the Default Servant It uses the Dynamic Skeleton Interface (DSI) to process the request Mode is USE_DEFAULT_SERVANT E Matching Requests to Servants IDL: module PortableServer { enum RequestProcessingPolicyValue { USE_ACTIVE_OBJECT_MAP_ONLY, USE_DEFAULT_SERVANT, USE_SERVANT_MANAGER interface RequestProcessingPolicy : CA::Policy { readonly attribute RequestProcessingPolicyValue value; Default Value: USE_ACTIVE_OBJECT_MAP_ONLY E.149

8 10 Retention of Object ID to Servant Associations Should the remember Servants and store them in the Active Object Map? Yes (RETAIN): searches Active Object Map No (NON_RETAIN): relies on Default Servant or Servant Manager to provide the association IDL: module PortableServer { enum ServantRetentionPolicyValue { RETAIN, NON_RETAIN interface ServantRetentionPolicy : CA::Policy { readonly attribute ServantRetentionPolicyValue value; Default Value: RETAIN E Multithreading How are requests allocated to threads? IDL: module PortableServer { enum ThreadPolicyValue { _CTRL_MODEL, SINGLE_THREAD_MODEL interface ThreadPolicy : CA::Policy { readonly attribute ThreadPolicyValue value; Default Value: _CTRL_MODEL E.151

9 12 Useful Policy Combinations Some combinations don t make sense and creation of such a fails PERSISTENT often used with USER_ID Easier to re-create servant if ObjectID contains a key to find the servant data IMPLICIT_ACTIVATION requires SYSTEM_ID Where should the ObjectID come from? E Simple without Implicit Activation Server Code new MyServant activate_object(org.omg.portableserver.servant):byte[] Add to Active Object Map id_to_reference(byte[]):org.omg.ca.object Dispatch Remote Call _invoke Find in Active Object Map Invoke the Real Method deactivate_object(byte[]):void Destroy Servant Remove from Active Object Map E.153

10 14 with Servant Activator Policies: USE_SERVANT_MANAGER RETAIN Application activates objects on demand via Servant Manager Application can deactivate objects using its own strategy Server Code new MyServantActivator set_servant_manager(org.omg.portableserver.servantmanager):void create_reference_with_id(byte[],java.lang.string):org.omg.ca.object E with Servant Activator Dispatch Remote Call MyServant incarnate(byte[],):servant new Find in Active Object Map _invoke Invoke Real Method Dispatch Remote Call _invoke Find in Active Object Map Invoke Real Method deactivate_object(byte[]):void etherealize(byte[],,servant,boolean,boolean):void Destroy Servant Remove from Active Object Map E.155

11 14 with Servant Activator Servant Manager is a Servant Activator (derived interface) interface org.omg.portableserver.servantmanageroperations interface org.omg.portableserver.servantactivatoroperations +incarnate(:byte[],:org.omg.portableserver.):org.omg.porta +etherealize(:byte[],:org.omg.portableserver.,:org.omg.po org.omg.portableserver.servant org.omg.ca.portable.invokehandler org.omg.portableserver.servantactivator MyServantActivator +incarnate(id:byte[],poa:):servant +etherealize(id:byte[],poa:,servant:servant,par4:boolea E with Servant Locator Policies: USE_SERVANT_MANAGER NON_RETAIN has no Active Object Map Servant Locator is consulted before and after each request Servant Locator implements own Active Object Map and eviction strategy Server Code new MyServantLocator set_servant_manager(org.omg.portableserver.servantmanager):void create_reference_with_id(byte[],java.lang.string):org.omg.ca.object E.157

12 15 with Servant Locator preinvoke(byte[],,string,cookieholder):servant Dispatch Remote Call MyServant new _invoke postinvoke(byte[],,string,object,servant):void preinvoke(byte[],,string,cookieholder):servant Dispatch Remote Call Find Servant _invoke postinvoke(byte[],,string,object,servant):void Destroy Servant Decide to destroy Servant E with Servant Locator Servant Manager is a Servant Locator (derived interface) interface org.omg.portableserver.servantmanageroperations interface org.omg.portableserver.servantlocatoroperations +preinvoke(:byte[],:org.omg.portableserver.,:java.lang.stri +postinvoke(:byte[],:org.omg.portableserver.,:java.lang.st org.omg.portableserver.servant org.omg.ca.portable.invokehandler org.omg.portableserver.servantlocator MyServantLocator +preinvoke(id:byte[],poa:,op:string,cookie:cookieholder) +postinvoke(id:byte[],poa:,op:string,cookie:object,servan E.159

13 16 with Default Servant Policies: USE_DEFAULT_SERVANT NON_RETAIN has no Active Object Map Application supplies Default Servant Default Servant gets each request of that and processes it using the Dynamic Skeleton Interface (DSI) E Interface attributes readonly attribute string the_name; readonly attribute the_parent; readonly attribute List the_children; readonly attribute Manager the_manager; attribute AdapterActivator the_activator; creation create_(in string adapter_name, in Manager a_manager, in CA::PolicyList policies) raises (AdapterAlreadyExists, InvalidPolicy); find_( in string adapter_name, in boolean activate_it) raises (AdapterNonExistent); void destroy( in boolean etherealize_objects, in boolean wait_for_completion); E.161

14 17 Interface Policy factory operations ThreadPolicy create_thread_policy( in ThreadPolicyValue value); LifespanPolicy create_lifespan_policy( in LifespanPolicyValue value); IdUniquenessPolicy create_id_uniqueness_policy( in IdUniquenessPolicyValue value); IdAssignmentPolicy create_id_assignment_policy( in IdAssignmentPolicyValue value); ImplicitActivationPolicy create_implicit_activation_policy( in ImplicitActivationPolicyValue value); ServantRetentionPolicy create_servant_retention_policy( in ServantRetentionPolicyValue value); RequestProcessingPolicy create_request_processing_policy( in RequestProcessingPolicyValue value); E Interface Servant Manager operations ServantManager get_servant_manager() raises (WrongPolicy); void set_servant_manager(in ServantManager imgr) raises (WrongPolicy); Default Servant operations Servant get_servant() raises (NoServant, WrongPolicy); void set_servant(in Servant p_servant) raises (WrongPolicy); Object activation and deactivation operations ObjectId activate_object(in Servant p_servant) raises (ServantAlreadyActive, WrongPolicy); void activate_object_with_id(in ObjectId id, in Servant p_servant) raises (ServantAlreadyActive, ObjectAlreadyActive, WrongPolicy); void deactivate_object(in ObjectId oid) raises (ObjectNotActive, WrongPolicy); E.163

15 17 Interface Identity mapping operations ObjectId servant_to_id(in Servant p_servant) raises (ServantNotActive, WrongPolicy); Object servant_to_reference(in Servant p_servant) raises (ServantNotActive, WrongPolicy); Servant reference_to_servant(in Object reference) raises(objectnotactive, WrongPolicy); ObjectId reference_to_id(in Object reference) raises (WrongAdapter, WrongPolicy); Servant id_to_servant(in ObjectId oid) raises (ObjectNotActive, WrongPolicy); Object id_to_reference(in ObjectId oid) raises (ObjectNotActive, WrongPolicy); Reference creation operations Object create_reference(in CA::Id intf) raises (WrongPolicy); Object create_reference_with_id(in ObjectId oid, in CA::Id intf) raises (WrongPolicy); E Persistent References Server Process starts and asks to create a reference Server Process at host2:1234 E.165

16 18 Persistent References Persistent registers server with Server Process at host2:1234 E Persistent References Server saves Persistent Object Reference returned by Object Reference for host2:4711 Server Process at host2:1234 E.167

17 18 Persistent References Server terminates Object Reference for host2:4711 E Persistent References Client starts and reads Object Reference Client Process at host1 Object Reference for host2:4711 E.169

18 18 Persistent References Client invokes operation Client Process at host1 Object Reference for host2:4711 E Persistent References Invocation request is sent to contact address, i.e. IR Client Process at host1 Object Reference for host2:4711 IIOP Request Message E.171

19 18 Persistent References IR starts Server Process Client Process at host1 Object Reference for host2:4711 Server Process at host2:9876 IIOP Request Message E Persistent References registers new contact address with IR Client Process at host1 Object Reference for host2:4711 Server Process at host2:9876 IIOP Request Message E.173

20 18 Persistent References IR returns location forward message with new contact address Client Process at host1 Object Reference for host2:4711 Server Process at host2:9876 IIOP LocationReply Message with host2:9876 E Persistent References Invocation request is re-sent to new contact address and executed Client Process at host1 Object Reference for host2:4711 Server Process at host2:9876 IIOP Request Message E.175

21 18 Persistent References Reply is returned to the client Client Process at host1 Object Reference for host2:4711 Server Process at host2:9876 IIOP Reply Message E Summary Hierarchy of s Many different policies All sorts of request processing and servant management strategies possible Persistent references via E.177