CSE812 Monday ( Feb. 14, 2003 ) and Wednesday (Feb. 16, 2003) Introduction to CORBA SeyedMasoud Sadjadi Software Engineering and Networking Systems Laboratory

CSE812 Monday (Feb. 14, 2003) and Wednesday (Feb. 16, 2003)

Introduction to Introduction to CORBACORBA

SeyedMasoud Sadjadi

Software Engineering and Networking Systems Laboratory

Department of Computer Science and Engineering

Michigan State University

www.cse.msu.edu/sens

CSE 812 04/14-16/2003 2Introduction to CORBA by SeyedMasoud Sadjadi

AcknowledgementsAcknowledgements

Object Management Group (OMG) IONA Technology Eternal Systems Steve Vinoski, IONA Technology Niall Stapley, CERN Mojtaba Hosseini


AgendaAgenda

Motivation

Introduction

Interoperability

Example

CORBA Evolution

Advance Features

Interoperability

Introduction

Motivation

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

Big Picture


Motivation (1)Motivation (1)

Object-oriented computational model– An application is represented by

interactions among a web of objects

Service provided through interface

Service is accessed through a referenceThread Main Loop

Interoperability

Introduction

Motivation

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture


Motivation (2)Motivation (2)

Distributed object computational model– Objects are distributed across network.– Tedious and error-prone programming.

So

cket

So

cket

Network

Application Layer

Operating SystemLayer

File

File

Sh

ared

S

har

ed

Mem

ory

Mem

ory

Pip

elin

eP

ipel

ine

So

cket

So

cket

File

File

Sh

ared

S

har

ed

Mem

ory

Mem

ory

Pip

elin

eP

ipel

ine

Interoperability

Introduction

Motivation

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture


Motivation (3)Motivation (3)MiddlewareMiddleware

SolutionSolution

So

cket

So

cket

StubSkeleton

Network

MiddlewareLayer

Operating SystemLayer

File

File

Sh

ared

S

har

ed

Mem

ory

Mem

ory

Pip

elin

eP

ipel

ine

So

cket

So

cket

File

File

Sh

ared

S

har

ed

Mem

ory

Mem

ory

Pip

elin

eP

ipel

ine

Application Layer

ORB ORB

Interoperability

Introduction

Motivation

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture


AgendaAgenda

Introduction

Motivation

Interoperability

Example

CORBA Evolution

Advance Features

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

Big Picture


What is CORBA?What is CORBA?

Common Object Request Broker Architecture

An industry standard developed by OMG to help in distributed programming

A specification for creating and using distributed objects

A tool for enabling multi-language, multi-platform communication

A CORBA based-system is a collection of objects that isolates the requestors of services (clients) from the providers of services (servers) by an encapsulating interface

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

CORBA

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

DII & DSI & IR

OA

Big Picture


Who should use CORBA?Who should use CORBA?

“The architecture and specifications described in the Common Object Request Broker Architecture and Specifications book are aimed at software designers and developers who want to produce applications that comply with OMG standards for the Object Request Broker (ORB)” [OMG].

“The benefit of compliance is, in general, to be able to produce interoperable applications that are based on distributed, interoperating objects” [OMG].

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

CORBA

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

DII & DSI & IR

OA

Big Picture


CORBA Features (1)CORBA Features (1)

Heterogeneity– Hardware devices– Operating System– Network protocols– Programming languages

Object Orientation– Encapsulation– Polymorphism– Inheritance– Instantiation

Dynamic binding and typing

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

DII & DSI & IR

OA

CORBA

Big Picture


CORBA Features (2)CORBA Features (2)

Transparencies– Location transparency

the physical address of a server is masked

– Access transparency the access method is masked

– Data transparency the different data representations are masked

– Replication transparency the server replicas are masked

– Migration transparency the migration of a server is masked

– Activation transparency the activation of a server is masked

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

DII & DSI & IR

OA

CORBA

Big Picture


CORBA ObjectsCORBA Objects

They are different from typical programming objects in three ways:

CORBA objects can run on any platform

CORBA objects can be located anywhere on the network

CORBA objects can be written in any language that has IDL mapping

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Objects

Features

Architecture

ORB

IDL

Stub & Skeleton

DII & DSI & IR

OA

CORBA

Big Picture


CORBA ArchitectureCORBA Architecture

CORBA is composed of ORB core, ORB interface, stub, skeleton, DII, DSI, and OA.

ClientClient Object ImplementationObject Implementation

DynamicDynamicInvocationInvocation

StaticStaticIDLIDLStubStub

ORBORBInterfaceInterface

Static IDL Static IDL SkeletonSkeleton

Dynamic Dynamic SkeletonSkeleton ObjectObject

AdapterAdapter

ORB CoreORB Core

Interface Identical for all ORB implementations Interface Identical for all ORB implementations

There may be multiple object adaptersThere may be multiple object adapters

There are stubs and a skeleton for each object typeThere are stubs and a skeleton for each object type

ORB-dependent interfaceORB-dependent interface

Up-call interfaceUp-call interface

Normal call interfaceNormal call interface

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Architecture

Features

Objects

CORBA

ORB

IDL

Stub & Skeleton

DII & DSI & IR

OA

Big Picture


Object Request Broker (1)Object Request Broker (1)

Responsibilities Object location transparency

– Find the object implementation for the request

Object activation– Prepare the object implementation to

receive the request Communication

– Communicate the data making up the request

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

ORB

Features

Objects

Architecture

CORBA

IDL

Stub & Skeleton

DII & DSI & IR

OA

Big Picture


Object Request Broker (2)Object Request Broker (2)

Both the client and the object implementation are isolated from the ORB by an IDL interface.

All requests are managed by the ORB, which means that invocation of a CORBA object is passed to an ORB

CORBA objects implemented in different ORBs from different vendors should be able to communicate with each other because all CORBA compliant ORBs are able to interoperate via IIOP (Internet Inter-ORB Protocol)

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

ORB

Features

Objects

Architecture

CORBA

IDL

Stub & Skeleton

DII & DSI & IR

OA

Big Picture


Interface Definition Language Interface Definition Language (1)(1)

Separates the Interface from the Implementation

Multiple-inheritance, strongly typed, public interface specification language

Independent of any particular language and compiler

Mappings will be provided for many languages and compilers

Not a programming language Enables Interoperability Supports the dynamic request

mechanism

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

IDL

Features

Objects

Architecture

ORB

Stub & Skeleton

DII & DSI & IR

OA

CORBA

Big Picture



The role of IDLThe role of IDL

I D L

I D L

I D L

I D L

I D L

I D L

ORB

C

C++

COBOL

Ada

Java

More

Client Side Server Side

COBOL

C

Ada

C++

Smalltalk

More

I D L

I D L

I D L

I D L

I D L

I D L

ORB

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

IDL

Features

Objects

Architecture

ORB

Stub & Skeleton

DII & DSI & IR

OA

CORBA

Big Picture



IDL File

Client StubFile

ServerSkeleton File

ClientImplementation

ObjectImplementation

IDL Compiler

Lang A Compiler Lang B Compiler

ClientProgram

ServerProgram

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

IDL

Features

Objects

Architecture

ORB

Stub & Skeleton

DII & DSI & IR

OA

CORBA

Big Picture



IDL Compiler It will accept as input an IDL file written

using any text editor (fileName.idl) It generates the stub and the skeleton

code in the target programming language (e.g., Java stub and C++ skeleton)

The stub is given to the client as a tool to describe the server functionality and the skeleton file is implemented at the server

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

IDL

Features

Objects

Architecture

ORB

Stub & Skeleton

DII & DSI & IR

OA

CORBA

Big Picture


Stubs and SkeletonsStubs and Skeletons

In terms of CORBA development, the stubs and skeleton files are standard in terms of their target language.

Each file exposes the same operations specified in the IDL file.

Invoking an operation on the stub file will cause the method to be executed in the skeleton file

The stub file allows the client to manipulate the remote object with the same ease with each a local file is manipulated

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Stub & Skeleton

Features

Objects

Architecture

ORB

IDL

DII & DSI & IR

OA

CORBA

Big Picture


Dynamic Invocation InterfaceDynamic Invocation Interface

Operations can be invoked through static or dynamic operations

Static invocation interfaces are determined at compile time being presented to the client using the stubs

The DII allows clients to use server objects without knowing about them at compile time

It allows the client to obtain an instance of a CORBA object and make invocations to it by dynamically constructing requests using the Interface Repository to retrieve an operation signature

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

OA

CORBA

DII & DSI & IR

Big Picture


Dynamic Skeleton InterfaceDynamic Skeleton Interface

Similar to DII, the server-side dynamic skeleton interface allows servers to be written without having skeletons, for the objects being implemented.

It allows dynamic handling of object invocations

It can use either the pure static knowledge of parameters or the Interface Repository to determine the parameters

Has other applications such as interactive software

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

OA

CORBA

DII & DSI & IR

Big Picture


Interface RepositoryInterface Repository

Provides another way to specify the interfaces to the objects.

Holds a table of interfaces A client, using the IR, should be able to

locate an object , find information about its interface, then make a request to be sent through the ORB

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

DII & DSI & IR

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

OA

CORBA

Big Picture


Object AdaptorsObject Adaptors

The primary way that an object implementation accesses services provided by ORB

Method invocation Security Object reference generation Object activation and deactivation

Interoperability

Motivation

Introduction

Example

Evolution

OvervieOverview:w:

Advanced

OA

Features

Objects

Architecture

ORB

IDL

Stub & Skeleton

DII & DSI & IR

CORBA

Big Picture


AgendaAgenda

Interoperability

Motivation

Introduction

Example

CORBA Evolution

Advance Features

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

Big Picture


Interoperability (1)Interoperability (1)

ORB from different vendors are interoperable

Obj. Impl.Obj. Impl.

IDL

ClientClient

IDL

ORB


IDL

ClientClient

IDL

ORB

ORB


IDL

ORB

ClientClient

IDL

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

Interoperability

IOR & IOGR

CORBA Clients

Java and CORBA

CORBA vs. RMI

CORBA vs. DCOM


Interoperability (2)Interoperability (2)

CORBA 2.0 Interoperability Comprises An overall architecture for CORBA-CORBA

communications An API for adding bridges A general multi-transport message format

(General Inter-ORB Protocol or GIOP) An API for gateways using ESIOPs

(Environment-Specific Inter-ORB Protocols)

UNIVERSAL, OUT-OF-THE-BOX INTEROPERABILITY

GIOP over TCP/IP is mandatory for compliance either internally or via a half-bridge

Specialized protocols are optional and well supported by the specifications.

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

Interoperability

IOR & IOGR

CORBA Clients

Java and CORBA

CORBA vs. RMI

CORBA vs. DCOM


IOR ExampleIOR Example

IOR:000000000000001049444c3a5472697669616c3a312e300000000001000000000000007c000102000000000d3135322e38312e342e3131300000048000000025abacab3131303033383632313336005f526f6f74504f410000cafebabe3bd5b8780000000000000000000001000000010000002c0000000000010001000000040001002000010109000101000501000100010109000000020001010005010001

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

IOR & IOGR

Interoperability

CORBA Clients

Java and CORBA

CORBA vs. RMI

CORBA vs. DCOM


Interoperable Object Group RefInteroperable Object Group Ref

…Type_idNumber

of Profiles IIOP Profile IIOP ProfileMultiple

Components Profile

tag_group_ version

ft_domain_id

object_group_id

object_group_version

TAG_INTERNET_IOP

ProfileBody

IIOP Version Host Port

Object Key Components

Number ofComponents

TAG_GROUPComponent

TAG_PRIMARYComponent

OtherComponents

corbaloc::1.2@hostA:683,:1.2@hostB:683/myObjIntroduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

IOR & IOGR

Interoperability

CORBA Clients

Java and CORBA

CORBA vs. RMI

CORBA vs. DCOM


Clients for CORBAClients for CORBA

CORBA Client – CORBA Server Java Client – CORBA, Java RMI, and HTTP

Server DCOM Client – CORBA and DCOM Server

standaloneCORBAclient

Windows app

COM/CORBA link

ORBORB

CORBAserver

HTTP

JAVA/RMIserver

HTTPserver

JAVA/CORBAclient

JAVA VM (browser)

JAVA ORBlet

DCOMserver

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

CORBA Clients

Interoperability

IOR & IOGR

Java and CORBA

CORBA vs. RMI

CORBA vs. DCOM


Java and CORBAJava and CORBA

Not just the usual IDL-to-Java Mapping A Java-to-IDL Mapping. Automates creation of CORBA Objects

from Java Classes Java RMI can use IIOP Protocol There’s an ORB in the JDK

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

Java and CORBA

Interoperability

CORBA Clients

IOR & IOGR

CORBA vs. RMI

CORBA vs. DCOM


CORBA vs. Java RMICORBA vs. Java RMI

CORBA was designed for language independence whereas RMI was designed for a single language where objects run in a homogeneous environment

CORBA interfaces are defined in IDL, while RMI interfaces are defined in Java

CORBA objects are not garbage collected because they are language independent and they have to be consistent with languages that do not support garbage collection, on the other hand RMI objects are garbage collected automatically

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

CORBA vs. RMI

Interoperability

CORBA Clients

Java and CORBA

IOR & IOGR

CORBA vs. DCOM


DCOM vs. CORBADCOM vs. CORBA

Introduction

Motivation

Interoperability

Example

Evolution

OvervieOverview:w:

Advanced

Big Picture

CORBA vs. DCOM

Interoperability

CORBA Clients

Java and CORBA

CORBA vs. RMI

IOR & IOGR


AgendaAgenda

Example

Motivation

Introduction

Interoperability

CORBA Evolution

Advance Features

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Big Picture


Steps to Implement “Hello Steps to Implement “Hello World”World”

We use a CROBA implementation such as ORBacus, ORBIX, VisiBroker, JacORB, and TAO

1. Define an interface using IDL

2. Use the IDL compiler

3. Implement the Hello object

4. Implement the server

5. Implement the client

6. Compile

7. Run

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Steps

Write Interface

Implement Hello

Implement Server

Implement Client

Compile and Run


Define Interface in IDLDefine Interface in IDL

public class Greeter{ public static void main(String args[]) { System.out.println("Hello World!"); }}

// IDLinterface Hello{ void say_hello();};

Stand-alone hello world application

1. Define an interface using IDL

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Write Interface

Steps

Implement Hello

Implement Server

Implement Client

Compile and Run


Implement the Hello ObjectImplement the Hello Object

jidl --package hello Hello.idl

2. Use the IDL compiler

// Javapackage hello;

public class Hello_impl extends HelloPOA { public void say_hello() { System.out.println("Hello World!"); }}

3. Implement the Hello object

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Implement Hello

Write Interface

Steps

Implement Server

Implement Client

Compile and Run


Implement the Server (1)Implement the Server (1)

4. Implement the Server


public class Server { public static void main(String args[]) { java.util.Properties props = System.getProperties(); props.put("org.omg.CORBA.ORBClass", "com.ooc.CORBA.ORB"); props.put("org.omg.CORBA.ORBSingletonClass", "com.ooc.CORBA.ORBSingleton");

int status = 0; org.omg.CORBA.ORB orb = null;

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Implement Server

Write Interface

Implement Hello

Steps

Implement Client

Compile and Run



4. Implement the Server (cont.)

try { orb = org.omg.CORBA.ORB.init(args, props); status = run(orb); } catch(Exception ex) { ex.printStackTrace(); status = 1; } if(orb != null) { try { orb.destroy(); } catch(Exception ex) { ex.printStackTrace(); status = 1; } } System.exit(status);}

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Implement Server

Write Interface

Implement Hello

Steps

Implement Client

Compile and Run




static int run(org.omg.CORBA.ORB orb) throws org.omg.CORBA.UserException {

org.omg.PortableServer.POA rootPOA = org.omg.PortableServer.POAHelper.narrow( orb.resolve_initial_references("RootPOA"));

org.omg.PortableServer.POAManager manager = rootPOA.the_POAManager();

Hello_impl helloImpl = new Hello_impl(); Hello hello = helloImpl._this(orb);

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Implement Server

Write Interface

Implement Hello

Steps

Implement Client

Compile and Run




try { String ref = orb.object_to_string(hello); String refFile = "Hello.ref"; java.io.PrintWriter out = new java.io.PrintWriter( new java.io.FileOutputStream(refFile)); out.println(ref); out.close(); } catch(IOException ex){ ex.printStackTrace(); return 1; }

manager.activate(); orb.run();

return 0; }}

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Implement Server

Write Interface

Implement Hello

Steps

Implement Client

Compile and Run


Implement the Client (1)Implement the Client (1)

5. Implement the Client


public class Client {

public static void main(String args[]) { ... // Same code as the server }

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Implement Client

Write Interface

Implement Hello

Steps

Implement Server

Compile and Run


Implement the Client (2)Implement the Client (2)

5. Implement the Client (cont.)

static int run(org.omg.CORBA.ORB orb) { org.omg.CORBA.Object obj = null; try { String refFile = "Hello.ref"; java.io.BufferedReader in = new java.io.BufferedReader( new java.io.FileReader(refFile)); String ref = in.readLine(); obj = orb.string_to_object(ref); } catch(IOException ex) {ex.printStackTrace(); return 1; }

Hello hello = HelloHelper.narrow(obj); hello.say_hello(); return 0; }}

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Implement Client

Write Interface

Implement Hello

Steps

Implement Server

Compile and Run


Compile and RunCompile and Run

6. Compile

CLASSPATH=.:your_orbacus_directory/lib/OB.jar:$CLASSPATHexport CLASSPATH

javac hello/*.java

7. Run

java hello.Server

java hello.Client

Introduction

Motivation

Example

Interoperability

Evolution

OvervieOverview:w:

Advanced

Big Picture

Compile and Run

Write Interface

Implement Hello

Steps

Implement Server

Implement Client


AgendaAgenda

CORBA Evolution

Motivation

Introduction

Example

Interoperability

Advance Features

Introduction

Motivation

Evolution

Example

Interoperability

OvervieOverview:w:

Advanced

Big Picture

Big Picture


CORBA Evolution (1)CORBA Evolution (1)

CORBA 3.0

Facilities

Interoperability

CORBA Core

1991

1996

1998

1999

IDL, ObjectModel, ORB

InteroperabilityNetworking

Horizontal,VerticalFacilities

CCMReal-time

Fault Tolerance

Introduction

Motivation

Evolution

Example

Interoperability

OvervieOverview:w:

Advanced

Big Picture



CORBA 1.0 (October 1991)– CORBA Object model – Interface Definition Language (IDL)– Core DII and Interface Repository – single language mapping for the C

CORBA 1.1 (February 1992)– The first widely published version– Interfaces for the Basic Object Adapter – Clarified some ambiguities

CORBA 1.2 (December 1993)– Closed several ambiguities in memory

management and object reference comparison.

Introduction

Motivation

Evolution

Example

Interoperability

OvervieOverview:w:

Advanced

Big Picture



CORBA 2.0 (August 1996)– Dynamic skeleton interface – Extensions to the Interface Repository – Interoperability (GIOP, IIOP, DCE CIOP) – Layered security and transaction services – Datatype extensions for COBOL– Interworking with OLE2/COM – Interoperability protocol specification– Interface repository improvements– C++ and Smalltalk IDL language mappings

CORBA 2.1 (August 1997)– Secure IIOP and IIOP over SSL– COBOL and Ada language maps

Introduction

Motivation

Evolution

Example

Interoperability

OvervieOverview:w:

Advanced

Big Picture



CORBA 2.2 (February 1998)– POA – DCOM Interworking– IDL/JAVA language mapping specification.

CORBA 2.3 (June 1999)– COM/CORBA Part A and B– Portability IDL/Java – Objects by value– Java to IDL Language Mapping – IDL to Java Language Mapping – C++ Language Mapping

Introduction

Motivation

Evolution

Example

Interoperability

OvervieOverview:w:

Advanced

Big Picture



CORBA 2.4 (October 2000)– Messaging specification – Interoperable Naming service – Notification service – Minimum and Real-time CORBA

CORBA 2.5 (September 2001)– Fault Tolerant – Messaging (editorial changes) – Portable Interceptors – Realtime CORBA, v1.2

CORBA 2.6 (December 2001)– Common Security

Introduction

Motivation

Evolution

Example

Interoperability

OvervieOverview:w:

Advanced

Big Picture



CORBA 3.0 (June 2002)– Java and Internet Integration

Objects Passable by Value (first in ver 2.3) Java-to-IDL Mapping (first in ver 2.3) Interoperable Name Service (first in ver 2.4) Firewall Specification

– Quality of Service Control Asynchronous Messaging (first in ver 2.4) Minimum (first in ver 2.4), Fault-Tolerant (first in

ver 2.5), and Real-Time CORBA (first in ver 2.4)

– The CORBA component architecture CORBAcomponents Scripting Languages

Introduction

Motivation

Evolution

Example

Interoperability

OvervieOverview:w:

Advanced

Big Picture


AgendaAgenda

Advanced Features

Motivation

Introduction

Interoperability

CORBA Evolution

Example

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Big Picture


POA Supports ScalabilityPOA Supports Scalability

Object implementation portability between ORBs

Object instances with persistent identities Transparent activation Single servant implementing multiple

instances Transient objects with minimal programming Fine or coarse control of behavior and

persistence by an implementation Multiple policies for key object behaviors Implementations inheriting from static

skeleton classes

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

QoS

CCM

Minimum CORBA

RT CORBA

FT CORBA

Others

POA


Objects by ValueObjects by Value

A struct with added value– They can have state and behaviour– Not CORBA objects– Can inherit from other valuetypes and

support interfaces Supports the CORBA component

model and Java to IDL reverse mapping

New keywords: valuetype, public, private, abstract

Uses a value factory to create local object

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

POA

QoS

CCM

Minimum CORBA

RT CORBA

FT CORBA

Others

Object by Value


Quality of Service (1)Quality of Service (1)

Provides policy-based QoS Framework No standard defaults – ORB vendor

sets them Policy areas

– Rebind Support– Request / Reply Priority– Request / Reply Timeout– Synchronization Scope– Routing

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

CCM

Minimum CORBA

RT CORBA

FT CORBA

Others

QoS



Specifying QoS Parameters – Specify for an Object Implementation

In an object reference, QoS requirements are expressed through a profile Component in the IOR

– Specify for a particular Request In a GIOP request, QoS requirements are expressed

as part of its Service Context

– CORBA resolves conflicts Asynchronous Method Invocation (AMI)

– Callback mode Similar to providing a callback handler object

– Polling mode Returns a valuetype object for client to check

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

CCM

Minimum CORBA

RT CORBA

FT CORBA

Others

QoS



Invocation Types– Synchronous: the reply is obtained and returned

to the client as part of the single (blocking, to the client) operation used by the client application to make the request.

– Deferred Synchronous: control returns to the application without a reply, but the client ORB still invokes synchronously on the target. The reply may be returned to the client later.

– Asynchronous: the client ORB does not synchronously invoke the target to obtain a reply. Some other agent separates the client ORB from the target.

– Time-Independent: a specialization of asynchronous invocation in which the computational context that obtains the reply may be different from the computational context from which the original invocation was made.

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

CCM

Minimum CORBA

RT CORBA

FT CORBA

Others

QoS



Ordering Invocations– ANY: the client doesn’t specify in what order its

requests are processed.

– TEMPORAL: requests that invocations be processed in the order in which they were issued. TEMPORAL is the default.

– PRIORITY: requests that invocations be processed based on the priority assigned in the QoS structure described later.

– DEADLINE: requests that invocations whose time_to_live is about to expire are moved to the front of the queue.

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

CCM

Minimum CORBA

RT CORBA

FT CORBA

Others

QoS


CORBA Component Model (1)CORBA Component Model (1)

Framework for designing, implementing and deploying CORBA components.

Purpose is to simplify and reduce effort by using a container that:– manages lifecycle– provides CORBA services– allows clean separation between

application logic and CORBA– Support for ready made components

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

Minimum CORBA

RT CORBA

FT CORBA

Others

CCM


CORBA Component Model (2)CORBA Component Model (2)

Two levels of component– Basic - fully compatible with EJB– Extended - components expose ports

Component categories– Session, Service, Entity, Process

More extra keywords like component, home, supports

Implementations?– K2 Component Server– MicoCCM– OpenCCM

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

Minimum CORBA

RT CORBA

FT CORBA

Others

CCM


Minimum CORBA (1)Minimum CORBA (1)

Designed systems with limited resources– Do not need everything that CORBA

provides– Has size and space limits

Some operations are omitted from Object, ORB

Other omissions– Dynamic Invocation Interface– Dynamic Skeleton interface– Dynamic any– Interface Repository

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

CCM

RT CORBA

FT CORBA

Others

Minimum CORBA


Minimum CORBA (2)Minimum CORBA (2)

The POA– Default policies only for:

create_thread_policy create_implicit_activation_policy create_servant_retention_policy create_request_processing_policy

– No dynamic activation of POAs– No ServantManagers

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

CCM

RT CORBA

FT CORBA

Others

Minimum CORBA


Real-Time CORBA (1)Real-Time CORBA (1)

Features– Adds QoS control capabilities to regular

CORBA.– Improve application predictability by

bounding priority inversion– Manage system resources end-to-end.

Processor resources Communication resources Memory resources

Shortcomings– Static fixed-priority real-time– Steep learning curve:

Cause by the complex C++ mapping.– Run-time and memory footprint overhead

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

CCM

Minimum CORBA

FT CORBA

Others

RT CORBA


Real-Time CORBA (2)Real-Time CORBA (2)

Real-time CORBA extensions

ORB RTORB

RTCORBA::Current

CORBA::Current

RTCORBA::Priority

SchedulingService

RTPOA

RTCORBA::Threadpool

(Others)ESIOPIIOP

(GIOP/TCP)RTCORBA::

PriorityMapping

POA

Servant

Client Server

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

CCM

Minimum CORBA

FT CORBA

Others

RT CORBA


Fault Tolerant CORBA (1)Fault Tolerant CORBA (1)

Aims to provide robust support for high reliability

Defines a fault-tolerance infrastructure Provides reliability by

– entity redundancy object replication (passive and active)

– request retry and redirection– fault detection and recovery

Multiple profiles in IOR– Example of a FT corbaloc URL

corbaloc::1.2@hostA:683,:1.2@hostB:683/myObj

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

CCM

Minimum CORBA

RT CORBA

Others

FT CORBA


Fault Tolerant CORBA (2)Fault Tolerant CORBA (2)

is_alive()

CORBA ORB CORBA ORBCORBA ORB

ReplicationManager

FaultNotifier

FaultDetector

Client

CServer

S1

Server

S2

LoggingMechanism

FactoryFault

Detector

RecoveryMechanism

LoggingMechanism

FactoryFault

Detector

RecoveryMechanism

LoggingMechanism

set_properties()

create_object()

notifications

fault reportscreate_object()

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

CCM

Minimum CORBA

RT CORBA

Others

FT CORBA


Other New SpecificationsOther New Specifications

Data Parallel Processing– Defines Architecture for parallel programming– Data is typically divided and redistributed

Unreliable Multicast (MIOP)– Deliver messages to many objects at once– Takes advantage of network ability– IDL operations would require oneway– Clients “join” a multicast group with a group IOR

Domain CORBAfacilities– “IDL is a great way to define standard interfaces for

standard objects that every company in an industry can share.”

Introduction

Motivation

Advanced

Interoperability

Evolution

OvervieOverview:w:

Example

Big Picture

Object by Value

POA

QoS

CCM

Minimum CORBA

RT CORBA

FT CORBA

Others


AgendaAgenda

Big Picture

Motivation

Introduction

Interoperability

CORBA Evolution

Advance Features

Introduction

Motivation

Big Picture

Interoperability

Evolution

OvervieOverview:w:

Advanced

Example

Example


Model Driven ArchitectureModel Driven Architecture

Open vendor-neutral approach Separating business logic from technologyIntroduction

Motivation

Big Picture

Interoperability

Evolution

OvervieOverview:w:

Advanced

Example

MDA

OMA


MDA SpecificationsMDA Specifications

MDA Specification Support The MDA Architecture The Unified Modeling Language (UML) UML Profiles The Meta-Object Facility (MOF) XML Metadata Interchange (XMI) Common Warehouse Metamodel (CWM) CORBA Writing Standards in the MDA Pervasive Services Domain (Industry-specific) Facilities MDA Applications

Introduction

Motivation

Big Picture

Interoperability

Evolution

OvervieOverview:w:

Advanced

Example

MDA

OMA


OMA Overview (1)OMA Overview (1)

ApplicationObjects

HorizomtalCORBA Facilities

Object Request Broker

CORBA Services

VerticalCORBA

Facilities

LifecycleEventsNamingPersistenceTransactionsConcurrency

ExternalizationSecurityTimePropertiesQueryLicensing

Compound DocsObject LinkingHelp FacilitiesDesktop Mgmt

Not standardized by OMG; Scope isSingle application or vendor

Business ObjectsHealthcareFinanceTelecommunication

OMG's vision for the component softwareIntroduction

Motivation

Big Picture

Interoperability

Evolution

OvervieOverview:w:

Advanced

Example

OMA

MDA


Object Management Object Management Architecture (2)Architecture (2)

Object Services – (a.k.a, CORBA Services)– Domain-independent services.– Naming Service and Trading Service.

Common Services – (a.k.a, Common Facilities and Horizontal Facilities)– are less oriented towards end-user applications.– Distributed Document Component Facility (DDCF).

Domain Services – (a.k.a, Domain Interfaces and Vertical Facilities)– are more oriented towards specific app domains. – Product Data Management (PDM) Enablers for the

manufacturing domain. Application Services

– (a.k.a, Application Interfaces and Application Objects)– are services developed specifically for a given application.

Introduction

Motivation

Big Picture

Interoperability

Evolution

OvervieOverview:w:

Advanced

Example

OMA

MDA


Vertical CORBA ServicesVertical CORBA Services

Official OMG specifications in vertical market domains:– Business Objects– Finance/Insurance– Electronic Commerce– Healthcare– Telecommunications– Transportation– Manufacturing– Life Sciences Research– Coming: Utilities, Statistics

Bring benefits of CORBA and OMA to Domains.

Introduction

Motivation

Big Picture

Interoperability

Evolution

OvervieOverview:w:

Advanced

Example

OMA

MDA


CORBA/OMA EnvironmentCORBA/OMA Environment

Starts with the Basics:– IDL Interfaces & Mappings– ORB-based Architecture– Static & Dynamic Invocation Modes– GIOP/IIOP Interoperability– Optional Asynchronous Modes– Naming Service– Event Service

Add Services and Facilities:– Security Service– Transaction Service– Object Trader Service– COM/CORBA Mapping

Then add Domain Componet

Introduction

Motivation

Big Picture

Interoperability

Evolution

OvervieOverview:w:

Advanced

Example

OMA

MDA

Documents

CSE812 Monday ( Feb. 14, 2003 ) and Wednesday (Feb. 16, 2003) Introduction to CORBA SeyedMasoud Sadjadi Software Engineering and Networking Systems Laboratory