1、Slides for Chapter 5: Distributed objects and remote invocationFrom Coulouris, Dollimore and KindbergDistributed Systems: Concepts and DesignEdition 4, Addison-Wesley 2005Instructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Fi

2、gure 5.1Middleware layersApplicationsMiddlewarelayers Request reply protocolExternal data representationOperating SystemRMI, RPC and eventsInstructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.2CORBA IDL example/ In fi

3、le Person.idlstruct Person string name; string place;long year; ;interface PersonList readonly attribute string listname;void addPerson(in Person p) ;void getPerson(in string name, out Person p);long number();Instructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and D

4、esign Edn. 4 Pearson Education 2005 Figure 5.3Remote and local method invocationsinvocationinvocationremoteinvocationremotelocallocallocalinvocationinvocationABCDEFInstructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.

5、4A remote object and its remote interfaceinterfaceremotem1m2m3m4m5m6Dataimplementationremoteobjectof methodsInstructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.5 Instantiation of remote objects Instructors Guide for

6、Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.6Invocation semanticsFault tolerance measuresInvocation semanticsRetransmit request messageDuplicate filteringRe-execute procedure or retransmit replyNoYesYesNot applicableNoYesNot appli

7、cableRe-execute procedureRetransmit replyAt-most-onceAt-least-onceMaybeInstructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.7The role of proxy and skeleton in remote method invocationobject Aobject BskeletonRequestpro

8、xy for BReplyCommunicationRemote Remote referenceCommunication module modulereference module modulefor Bs class& dispatcherremoteclient serverservantInstructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.8 Role of clien

9、t and server stub procedures in RPC in the context of a procedural languageclient RequestReplyCommunicationCommunication module moduledispatcherservice client stub server stubprocedureprocedureclient process server process procedureprogram Instructors Guide for Coulouris, Dollimore and Kindberg Dist

10、ributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.9Files interface in Sun XDRconst MAX = 1000;typedef int FileIdentifier;typedef int FilePointer;typedef int Length;struct Data int length;char bufferMAX;struct writeargs FileIdentifier f;FilePointer position;Data data;struct

11、readargs FileIdentifier f;FilePointer position;Length length;program FILEREADWRITE version VERSION void WRITE(writeargs)=1;1Data READ(readargs)=2;2 =2; = 9999;Instructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.10Dea

12、ling room systemDealers computerInformationproviderDealerExternalsourceExternalsourceInformationproviderDealerDealerDealerNotificationNotificationNotificationNotificationNotificationNotificationNotificationNotificationDealers computerDealers computerDealers computerNotificationNotificationInstructor

13、s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.11Architecture for distributed event notificationsubscriberobserverobject of interestEvent serviceobject of interestobject of interestobserversubscribersubscriber3.1.2.notifi

14、cationnotificationnotificationnotificationInstructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.12Java Remote interfaces Shape and ShapeListimport java.rmi.*;import java.util.Vector;public interface Shape extends Remot

15、e int getVersion() throws RemoteException;GraphicalObject getAllState() throws RemoteException;1public interface ShapeList extends Remote Shape newShape(GraphicalObject g) throws RemoteException;2Vector allShapes() throws RemoteException;int getVersion() throws RemoteException;Instructors Guide for

16、Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.13The Naming class of Java RMIregistryvoid rebind (String name, Remote obj) This method is used by a server to register the identifier of a remote object by name, as shown in Figure 15.1

17、3, line 3. void bind (String name, Remote obj) This method can alternatively be used by a server to register a remote object by name, but if the name is already bound to a remote object reference an exception is thrown.void unbind (String name, Remote obj) This method removes a binding.Remote lookup

18、(String name) This method is used by clients to look up a remote object by name, as shown in Figure 15.15 line 1. A remote object reference is returned.String list() This method returns an array of Strings containing the names bound in the registry.Instructors Guide for Coulouris, Dollimore and Kind

19、berg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 2005 Figure 5.14Java class ShapeListServer with main methodimport java.rmi.*;public class ShapeListServerpublic static void main(String args)System.setSecurityManager(new RMISecurityManager(); tryShapeList aShapeList = new ShapeL

20、istServant();1 Naming.rebind(Shape List, aShapeList );2System.out.println(ShapeList server ready); catch(Exception e) System.out.println(ShapeList server main + e.getMessage();Instructors Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 Pearson Education 20

21、05 Figure 5.15Java class ShapeListServant implements interface ShapeListimport java.rmi.*;import java.rmi.server.UnicastRemoteObject;import java.util.Vector;public class ShapeListServant extends UnicastRemoteObject implements ShapeList private Vector theList; / contains the list of Shapes1 private i

22、nt version;public ShapeListServant()throws RemoteException.public Shape newShape(GraphicalObject g) throws RemoteException 2version+; Shape s = new ShapeServant( g, version);3 theList.addElement(s); return s;public Vector allShapes()throws RemoteException. public int getVersion() throws RemoteException . Instructors Guide for Coulouris, Dollimore and Kindberg Distributed System