Copyright © 2003 ProsoftTraining. All rights reserved. Distributed Object Computing Using Java and CORBA

Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 1: Introduction to CORBA

Objectives Describe the role of CORBA in developing enterprise applications Describe the role of the Object Management Group Describe the CORBA architecture

CORBA Overview Common Object Request Broker Architecture Object-oriented development Distributed-object computing

The Object Management Group Controls the CORBA standard Provides a specification for CORBA

CORBA Architecture Object Management Architecture –Object Request Broker –Object services –Common facilities –Application objects –Internet InterORB Protocol –Interface Definition Language –Object adapters –CORBA Services

Object Request Broker

Internet InterORB Protocol

Interface Definition Language

Summary Describe the role of CORBA in developing enterprise applications Describe the role of the Object Management Group Describe the CORBA architecture

Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 2: Interface Definition Language

Objectives Use the IDL to define the interface to CORBA objects Describe the mapping of IDL nonclass data types into Java Describe the purpose of IDL parameter- passing modes Model inheritance using IDL Define CORBA exceptions using IDL

Introduction to IDL IDL files IDL compilers Mapping IDL to Java

Basics of IDL IDL constructs –Modules –Interfaces –Attributes –Operations

IDL Primitives IDLJava boolean char, wcharchar octetbyte string, wstringjava.lang.String short, unsigned shortshort long, unsigned longint long long, unsigned long longlong float double

Inheritance and IDL Java  no multiple inheritance support Java class  can inherit from only one other class IDL  can be used to define an interface that inherits from multiple super-interfaces

Nonclass Data Types Constants Enumerations Unions Structures Type definitions Sequences Arrays

Parameter-Passing Modes and Exceptions Parameter-passing modes –in –out –inout Exceptions –Use-defined exceptions inherit indirectly from java.lang.Exception –IDL operations must declare their ability to raise an exception

Summary Use the IDL to define the interface to CORBA objects Describe the mapping of IDL nonclass data types into Java Describe the purpose of IDL parameter- passing modes Model inheritance using IDL Define CORBA exceptions using IDL

Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 3: Building CORBA Clients

Objectives Use the IDL compiler to generate client stubs Initialize the ORB Use the naming service to obtain an object reference Invoke remote methods Use out and inout parameters to invoke remote methods

Client IDL Stubs Used to create client applications IDL-to-Java compiler named idlj –Used to compile IDL files to generate client stubs and server skeletons

Initializing the ORB The ORB class –Is used to initialize the ORB –Is not instantiated using its public constructor –Provides a static method named init that initializes the ORB and returns an instance of the ORB class

Using the Naming Service Connecting to the naming service Using the naming service to obtain an object reference –Obtaining the initial naming context –Retrieving an object reference

Example of Namespace

Invoking Remote Methods Remote methods are invoked in the same way that local methods are invoked

Using Out and Inout Parameters Out parameters –Used exclusively to return data from the server to the client Inout parameters –Passed both from the client to the server and, following any changes, from the server back to the client

Summary Use the IDL compiler to generate client stubs Initialize the ORB Use the naming service to obtain an object reference Invoke remote methods Use out and inout parameters to invoke remote methods

Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 4: Building CORBA Servers

Objectives Use the IDL compiler to generate server skeletons Implement CORBA objects Initialize the ORB and wait for clients Use the naming service to publish an object reference Use out and inout parameters

Server IDL Skeletons A server skeleton provides a framework for the implementation of a CORBA object

Implementing CORBA Objects Server-side implementation

Using the Naming Service Instantiating a CORBA object Creating additional naming contexts

Example of Naming Service

Waiting for Invocation The wait method –Called to pause the main thread of execution –Part of Java’s built-in threading facilities

Using Out and Inout Parameters Out parameters –Used exclusively to return data from the server to the client Inout parameters –Passed both from the client to the server and, following any changes, from the server back to the client

Summary Use the IDL compiler to generate server skeletons Implement CORBA objects Initialize the ORB and wait for clients Use the naming service to publish an object reference Use out and inout parameters

Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 5: Factory and Callback Objects

Objectives Describe the purpose of factory objects Use factory objects to obtain object references Describe the purpose of callback objects Develop applications that use callback objects

Factory Objects Types include: –Generic –Specific –In-process –Out-process FactoryFinder Using factory objects Designing factory objects

Callback Objects Using callback objects Designing callback objects

Summary Describe the purpose of factory objects Use factory objects to obtain object references Describe the purpose of callback objects Develop applications that use callback objects

Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 6: CORBA Exceptions

Objectives Describe the purpose of CORBA exceptions Define an exception using IDL Develop CORBA objects that throw exceptions

Introduction to CORBA Exceptions Throwing CORBA exceptions Catching CORBA exceptions

Summary Describe the purpose of CORBA exceptions Define an exception using IDL Develop CORBA objects that throw exceptions

Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 7: Dynamic Invocation Interface

Objectives Describe the purpose of the interface repository Describe the Dynamic Invocation Interface Construct an argument list for use in dynamic invocation Invoke a request using the DII Extract a return value following dynamic invocation

Dynamic Invocation Interface Introduction DII allows a client to access any CORBA object even though it may not have a client stub to provide a compile-time definition of an object’s interface

Invoking a Remote Method Using DII Construct a list of arguments Prepare a place to hold a return value Invoke the remote method Extract the return value

Summary Describe the purpose of the interface repository Describe the Dynamic Invocation Interface Construct an argument list for use in dynamic invocation Invoke a request using the DII Extract a return value following dynamic invocation

Distributed Object Computing Using Java and CORBA Introduction to CORBA Interface Definition Language Building CORBA Clients Building CORBA Servers Factory and Callback Objects CORBA Exceptions Dynamic Invocation Interface