Transcript Document 3159078

CORBA and Java
 by Alex
Chaffee
 [email protected]
 http://www.jguru.com/
 Java
online resources
 http://www.purpletech.com/
 Java
training and consulting
Copyright © 1998 Purple Technology, Inc
Abstract

CORBA loves Java! CORBA provides a platform-independent,
language-independent way to write applications that can invoke
objects that live across the room or across the planet. Java is an
object-oriented language that's ideal for writing the clients and
servers living on the Object Bus. In this session, we examine the
ways they interoperate programmatically, as we walk you stepby-step from a CORBA IDL, to a server and client both written in
Java, running on top of a 100%-Java ORB. We also discuss the
relationship between CORBA and RMI, and discuss some of the
real-world issues involved in deploying a CORBA-based
application. Recommended: some knowledge of CORBA, ability
to read Java source code.
Copyright © 1998 Purple Technology, Inc
Introduction
 Purple
Technology
 http://www.purpletech.com
 Java
 Alex
Training and Consulting
Chaffee
 Creator
of Gamelan
 Cool Java Dude
Copyright © 1998 Purple Technology, Inc
Part I: CORBA Overview
Copyright © 1998 Purple Technology, Inc.
What is CORBA?
 Common
Object Request Broker
Architecture
 Communication infrastructure for
distributed objects
 Allows a heterogeneous, distributed
collection of objects to collaborate
transparently
Copyright © 1998 Purple Technology, Inc
What is CORBA good for?
 Developing
distributed applications
 Locating remote objects on a network
 Sending messages to those objects
 Common interface for transactions,
security, etc.
 CORBA
Services (more later)
Copyright © 1998 Purple Technology, Inc
Why Distributed
Applications?
 Data
is distributed
 Administrative
and ownership reasons
 Heterogeneous systems
 Shared by multiple applications
 Scalability
Copyright © 1998 Purple Technology, Inc
Why Distributed
Applications?
 Computation
is distributed
 Scalability:
multiprocessing
 Take computation to data
 Heterogeneous architectures
 Users
are distributed
 Multiple
users interacting and
communicating via distributed applications
Copyright © 1998 Purple Technology, Inc
Distributed Object Systems
 All
entities are modeled as objects
 Systems support location transparency
 Interfaces, not implementations, define
objects
 Good distributed object systems are
open, federated systems
Copyright © 1998 Purple Technology, Inc
What is the OMG?
 Designers
of CORBA
 Consortium of 700+ companies
 Not
including Microsoft
 Members:
 platform
vendors
 database
 software
tool developers
 corporate
 software
vendors
developers
application vendors
Copyright © 1998 Purple Technology, Inc
It’s Just A Spec
 Has
never been fully implemented
 Probably never will be
 Industry moves quickly and spec has to
keep up
 Interoperability
vs. portability
 Pass-by-value
Copyright © 1998 Purple Technology, Inc
Basic CORBA Architecture
Server
Client
response
request
ORB
ORB
“Object Bus”
Copyright © 1998 Purple Technology, Inc
CORBA Objects

Examples
 Service
 Client
 Component
 Business

object
CORBA objects approach universal
accessibility
 Any
Language
 Any Host on network
 Any Platform
Copyright © 1998 Purple Technology, Inc
CORBA Elements
 1.
ORB
 2. CORBA Services
 3. CORBA Facilities
 4. Application Objects
Copyright © 1998 Purple Technology, Inc
ORB
 Object
Request Broker
 “Object
 Handles
Bus”
all communication among
objects
 Each host (machine) has its own ORB
 ORBs know how to talk to each other
 ORB also provides basic services to
client
Copyright © 1998 Purple Technology, Inc
ORB Responsibilities
 Find
the object implementation for the
request
 Prepare the object implementation to
receive the request
 Communicate the data making up the
request
 Retrieve results of request
Copyright © 1998 Purple Technology, Inc
Network of ORBs
 There’s
an ORB on the server too
 ORB receives request
Copyright © 1998 Purple Technology, Inc
IIOP
 Internet
Inter-Orb Protocol
 Network or “wire” protocol
 Works across TCP/IP (the Internet
protocol)
Copyright © 1998 Purple Technology, Inc
ORB Features
 Method
invocations
 Static
and Dynamic
 Remote objects or CORBA services
 High-level
language bindings
 Use
your favorite language; ORB
translates
 Self-describing
 Provides
services
metadata for all objects and
Copyright © 1998 Purple Technology, Inc
ORB Features
 Local
or remote
 Same
API wherever target object lives
 Preserves
context
 Distributed
security and transactions
 Coexistence
 Just
with legacy code
provide a wrapper object
Copyright © 1998 Purple Technology, Inc
What is an ORB really?
 Not
a separate process
 Library code that executes in-process
 Listens to TCP ports for connections
 One
port per local object
 Opens
N
TCP sockets to other objects
ports per remote machine
Copyright © 1998 Purple Technology, Inc
IDL
 Interface
Definition Language
 Defines protocol to access objects
 Like a contract
 Well-specified
 Language-independent
Copyright © 1998 Purple Technology, Inc
IDL Example
module Calc {
interface Adder {
long add(in long x, in long y);
}
}
 Defines
an object called Adder with a
method called add
Copyright © 1998 Purple Technology, Inc
Stubs and Skeletons
 Stub
 lives
on client
 pretends to be remote object
 Skeleton
 lives
on server
 receives requests from stub
 talks to true remote object
 delivers response to stub
Copyright © 1997 Alex Chaffee
Stubs and Skeletons (Fig.)
Client Host Machine
Server Host Machine
Client
Object
Remote
Object
Stub
Skeleton
ORB
IIOP
ORB
Copyright © 1997 Alex Chaffee
Client vs. Server
 in
CORBA, a client is a client relative to
a particular object
 i.e. an object with a reference to a
“server” object
 A client may also act as a server
 If
it has an IDL and stubs and skeletons
 Technically,
a CORBA server contains
one or more CORBA objects
Copyright © 1998 Purple Technology, Inc
Different Meanings of
“Server”
 Host
machine
 Program running on host machine
 CORBA object running inside program
 has
IDL, stub, skeleton
 Sometimes called a Servant
Copyright © 1998 Purple Technology, Inc
Stubs and Skeletons ->
Platform Independence
 Client
code has no knowledge of the
implementation of the object or which ORB
is used to access the implementation.
Copyright © 1998 Purple Technology, Inc
CORBA Services
 APIs
for low-level, common tasks
 Life Cycle Service
 creating,
copying, moving, removing
objects
 Naming
Service
 Register
objects with a name
 Look up objects by name
Copyright © 1998 Purple Technology, Inc
CORBA Services
 Concurrency
 Obtain
Control Service
and release exclusive locks
 Transaction
Service
 Two-phase
commit coordination
 Supports nested transactions
 Persistence
Service
 Storing
objects in a variety of databases
 RDBMS, OODBMS, file systems
Copyright © 1998 Purple Technology, Inc
CORBA Services
 Security
Service
 Authentication, ACLs,
 Event
encryption, etc.
Service
 Uncoupled
notifications
Copyright © 1998 Purple Technology, Inc
CORBA Services
 Relationship

Externalization

Query
Licensing
Properties



Time
Trader

Collection

… and so on…

 See
what I mean about it never being
Copyright © 1998 Purple Technology, Inc
implemented?
CORBA Facilities
 Frameworks
for specialized applications
 Distributed Document Component
Facility
 OpenDoc
 In
progress:
 Agents
 Business
Objects
 Internationalization
Copyright © 1998 Purple Technology, Inc
N-Tier Design with CORBA
Storage “Tier”
ORB
DB
ORB
ORB
ORB
DB
Data Object
ORB
ORB
ORB
ORB
Client Tier
TP Monitor
ORB
Business Object
Tier
(after diagram in Orfali et al.)
Service “Tier”
Copyright © 1998 Purple Technology, Inc
Three Tiers
 User
Interface Tier
 Business Logic Tier
 Data Storage Tier
 Can use CORBA objects in each tier
Copyright © 1998 Purple Technology, Inc
Part II: Java IDL - Using
CORBA from Java
Copyright © 1998 Purple Technology, Inc.
Java CORBA Products
 The
Java 2 ORB
 VisiBroker for Java
 OrbixWeb
 Netscape Communicator
 Various free or shareware ORBs
Copyright © 1998 Purple Technology, Inc
Java IDL
 Should
be named “Java CORBA”
 More
than just IDL
 Full (?) implementation of CORBA in 100%
Java
 Three
Parts
 ORB
 Naming
Service
 idltojava compiler
 Ships
with JDK 1.2
Copyright © 1998 Purple Technology, Inc
Transparent API
 JavaIDL
turns IDL into direct method
calls
 Easy to program
 Clients have no knowledge of
implementation
 Highly portable
Copyright © 1998 Purple Technology, Inc
The Java ORB
 100%
Java
 Generic
 Allows Java IDL applications to run
either as stand-alone Java applications,
or as applets within Java-enabled
browsers
 Uses IIOP
Copyright © 1998 Purple Technology, Inc
Other Java ORBs
 Visigenic
(Inprise) VisiBroker
 Netscape
Communicator
 Oracle Web Server 3.0
 Free download
 Iona
OrbixWeb
Copyright © 1998 Purple Technology, Inc
IDL to Java Mapping
 Defined
by OMG
 Translates IDL concepts into Java
language constructs
 Everything is accessible by writing
normal-looking Java code
Copyright © 1998 Purple Technology, Inc
IDL to Java Type Mapping
IDL Type
boolean
char / wchar
octet
short / unsigned short
long / unsigned long
long long / unsigned long long
float
double
string / wstring
Java Type
boolean
char
byte
short
int
long
float
double
String
Copyright © 1998 Purple Technology, Inc
IDL vs. Java vs. C++
concepts
IDL
module
Java
package
C++
namespace
interface
interface abstract
class
operation
method
member
function
attribute
pair of
methods
pair of
functions
Copyright © 1998 Purple Technology, Inc
IDL Modules
 Map
to Java packages
 Unfortunately, it has the root level name
of the module
 Clutters up your package hierarchy
 e.g. module Calc ->
 package
Calc
 interface Calc.Adder
 not package
ORG.omg.CORBA.modules.Calc
Copyright © 1998 Purple Technology, Inc
IDL Interfaces
 Map
to Java interfaces
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IDL Operations
 Map
to Java methods
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IDL Attributes
 Map
to pair of functions
 IDL
 string
name;
 Java
 public
void name(String val);
 public String name();
 Yes,
it looks stupid. Sorry.
Copyright © 1998 Purple Technology, Inc
idltojava
 Development
tool
 Automatically generates java stubs,
skeletons, helpers, holders, ...
 Generates stubs for specific remote
interfaces
Copyright © 1998 Purple Technology, Inc
Stubs
 Java
objects call stub methods
 Stubs communicate with CORBA
objects
 and
vice versa
 Transparent
integration
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Skeletons
 ORB
passes request to skeleton (like a
stub)
 Skeleton calls local implementation
Copyright © 1998 Purple Technology, Inc
Remote Interfaces and
Stubs
IDL Interface
implements
implements
extends
Client
Stub
Skeleton
Remote Object
(Server)
Copyright © 1997 Alex Chaffee
Show Me The Source Code
 OK,
here it comes...
Copyright © 1998 Purple Technology, Inc
idltojava input
 Calc.idl
module Calc {
interface Adder {
long add(in long x, in long y);
}
}
Copyright © 1998 Purple Technology, Inc
idltojava output
 idltojava
Calc.idl

Adder.java (a Java interface that
maps the IDL interface)

_AdderStub.java (a client stub)

_AdderImplBase.java (a server
skeleton)

AdderHelper.java (a helper class)

AdderHolder.java (a holder class)
 Must
compile these files and put them in
your CLASSPATH
Copyright © 1998 Purple Technology, Inc
Adder.java
 Created
for you by idltojava
package Calc;
public interface Adder
extends
org.omg.CORBA.Object {
int add(int x, int y);
}
Copyright © 1998 Purple Technology, Inc
Implementing a server
 Extend
base class
 Implement
 Provide
 Create
all methods declared in IDL
a main method
an ORB instance
 Create a server instance
 Inform the ORB about the instance
 Acquire a Naming Context
 Register the instance in that Naming
Context under some name Copyright © 1998 Purple Technology, Inc
AdderServer.java
class AdderServer extends _AdderImplBase
{
public int add( int x, int y ) {
System.out.println(x + " + " + y + "
= " + (x+y));
return x + y;
}
Copyright © 1998 Purple Technology, Inc
AdderServer.java (cont.)
public static void main(String args[]) {
// create and initialize the ORB
ORB orb = ORB.init(args, null);
// create server and register it with
the ORB
AdderServer adderRef = new
AdderServer();
orb.connect(adderRef);
Copyright © 1998 Purple Technology, Inc
AdderServer.java (cont.)
// get the root naming context
org.omg.CORBA.Object objRef =
orb.resolve_initial_references("NameSer
vice");
NamingContext ncRef =
NamingContextHelper.narrow(objRef);
// bind the Object Reference in Naming
NameComponent nc = new
NameComponent("Adder", "");
NameComponent path[] = {nc};
ncRef.rebind(path, adderRef);
Copyright © 1998 Purple Technology, Inc
Implementing a client
 Create
an ORB
 Get a reference to the Naming Context
 Look up the correct name in that
Naming Context
 Receive an object reference to that
object
 Actually,
 Invoke
to its Stub
methods on the reference
Copyright © 1998 Purple Technology, Inc
AdderClient.java
Copyright © 1998 Purple Technology, Inc
Object Reference
 Two
Meanings
 1. An
abstract concept referring to a
specific object living on a specific host,
attached to a specific ORB
 2. A local Java reference to an object that
relays messages to that object
 Obtained
from
 new
keyword
 a Factory Object
 the Naming Service
Copyright © 1998 Purple Technology, Inc
Naming Service
 tnameserv
t
is for “transient”
 Maps
name to object reference
 An implementation of the CORBA
Object Service (COS) name service
 to run the Naming Service
 UNIX:
tnameserv &
 Win32:
start /m tnameserv
Copyright © 1998 Purple Technology, Inc
Fire it up
 start
/m tnameserv
 start java AdderServer
 java AdderClient
2 + 2 = ?
Copyright © 1998 Purple Technology, Inc
CORBA Flow
Client Virtual Machine
Server Virtual Machine
Client
Remote
Object
Skeleton
Stub
Server
“Fred”
Name Server Virtual Machine
Copyright © 1997 Alex Chaffee
CORBA Flow
1. Server Creates Remote Object
Client Virtual Machine
2. Server Registers Remote Object
Client
Server Virtual Machine
Remote
Object
1
Skeleton
Stub
Server
2
“Fred”
Name Server Virtual Machine
Copyright © 1997 Alex Chaffee
CORBA Flow
Client Virtual Machine
3. Client requests object fromRemote
Name Server
4. Name Server returns remote
reference
Object
(and stub gets created)
Client
Skeleton
Stub
3
Server Virtual Machine
Server
4
“Fred”
Name Server Virtual Machine
Copyright © 1997 Alex Chaffee
RMI Flow
Client Virtual Machine
Server Virtual Machine
Client
Remote
Object
5
7
6
Stub
Skeleton
Server
5. Client invokes stub method
6. Stub talks to skeleton
7. Skeleton invokes remote object
“Fred”
method
Name Server Virtual Machine
Copyright © 1997 Alex Chaffee
Pseudo-objects
 The
ORB is a pseudo-object
 It works just like a remote object, only
it’s local
Copyright © 1998 Purple Technology, Inc
The Basic Object Adapter
(BOA)
 Another
pseudo-object
 Helps register objects with the ORB
 Functions
 Maintain
Implementation Repository
 Generate and interpret object references
 Activate and deactivate implementation
objects
 Invoke methods via skeletons
Copyright © 1998 Purple Technology, Inc
Why do you need both an
ORB and a BOA?
 I’m
not really sure
 Allows vendors to optimize or enhance
functionality
 register
many objects en masse
 cache object state elsewhere
 E.g.
Object database
Copyright © 1998 Purple Technology, Inc
Using the BOA
 Slightly
different procedure for
initializing objects
 Hides name service from you
 Ask
the BOA to register the object
 Ask the Helper object to bind the object
 Once
the object is created, interface is
identical
 Just
call methods using normal Java
syntax
Copyright © 1998 Purple Technology, Inc
BOA Object Activation
 Shared
server
 Multiple
objects, one server
 Normal procedure
 Multithreaded (handled by CORBA
implementation)
 Unshared
 New
server
process for each object
Copyright © 1998 Purple Technology, Inc
BOA Object Activation
(cont.)
 Server-per-method
 Batch
processing
 Persistent
 Shared
server
server, but object not created by
ORB
Copyright © 1998 Purple Technology, Inc
BOA Object Activation
Scenario
 Server
 obj
creates object instance
= new MyObject();
 Server
registers object with BOA
 boa.create(interface_name,
implementation_name, reference_data)
 VisiBroker does this for you in superclass
constructor
Copyright © 1998 Purple Technology, Inc
BOA Object Activation
Scenario (cont.)
 Server
tells BOA the object is ready
 boa.obj_is_ready(obj)
 Server
tells BOA that all objects are
ready
 boa.impl_is_ready()
 Objects
shut down
 boa.deactivate_obj(this)
 Server
shuts down
 boa.deactivate_impl()
Copyright © 1998 Purple Technology, Inc
Threads in JavaIDL
 Remote
invocations happen on a
separate thread
 Must make sure your remote objects
are thread-safe
Copyright © 1998 Purple Technology, Inc
Callbacks
 Pass
in a reference to some CORBA
object
 The server object can invoke methods
on that reference
 ORB automatically generates a stub on
the server side
 The server has become the client, and
vice versa
Copyright © 1998 Purple Technology, Inc
Obtaining Object
References
 From
the ORB
 orb.resolve_initial_references(“NameServic
e”)
 From
a Naming Context
 From a Stringified reference
 From another object
 From a parameter to your remote
method
Copyright © 1998 Purple Technology, Inc
Helper Objects
 How
CORBA does casting
 narrow method changes the type of an
object reference
// get the root naming context
org.omg.CORBA.Object objRef =
orb.resolve_initial_references("NameSer
vice");
NamingContext ncRef =
NamingContextHelper.narrow(objRef);
Copyright © 1998 Purple Technology, Inc
Naming Contexts
 Directory
structure for CORBA
 Naming Component = file
 Naming Context = directory
 Can add a Context as a Component
 like
subdirectories
 Can
add a Context on a different name
server
 like
symbolic links
Copyright © 1998 Purple Technology, Inc
Stringification
 Stringified
reference is ORBindependent
 Object to string
org.omg.CORBA.Object obj = ...
String str = orb.object_to_string(obj);
 String to object
 org.omg.CORBA.Object obj =
orb.string_to_object(str);
Copyright © 1998 Purple Technology, Inc
Visigenic: Caffeine
 Java
to IDL compiler
Copyright © 1998 Purple Technology, Inc
Symantec: Visual Café 3.0
Enterprise Suite
 Java
to IDL compiler
 Automatic client adapter bean
generation
 Makes
a JavaBean that’s a proxy to a
CORBA object
 Distributed
debugging
 Follow
call chain, examine variables, et al.
 Across many VMs, many hosts, many OSs
Copyright © 1998 Purple Technology, Inc
Part III: Example
Application
Copyright © 1998 Purple Technology, Inc
Publish-Subscribe System
 Channel:
an avenue for real-time data
exchange
 Consumers can subscribe to arbitrary
data channels
 Producers can publish data on channels
 Invokes
callback method on consumer
Copyright © 1998 Purple Technology, Inc
Object Model
 PSServer
 Channel
 creates
getChannel(String channelName)
channel if it doesn’t already exist
 Channel
 void
subscribe(Subscriber sub)
 void publish(Object data)
 Subscriber
 void
dataArrived(Object data)
Copyright © 1998 Purple Technology, Inc
Flow: Subscriber-side
 Client
acquires PSServer reference
 Client acquires channel from PSServer
 Client creates subscriber locally,
passing reference to channel
 Subscriber registers self with channel
 channel.subscribe(this)
 Client
waits for callback to its
dataArrived method
Copyright © 1998 Purple Technology, Inc
Flow: Publisher-side
 Client
acquires PSServer reference
 Client acquires channel from PSServer
 Client creates publisher locally, passing
reference to channel
 Publisher acquires data
 From
a database
 From a data feed
 Publisher
calls channel.publish(data)
Copyright © 1998 Purple Technology, Inc
Example Application: Stock
data
 Channel
name = stock symbol name
 Source code available
Copyright © 1998 Purple Technology, Inc
Design issues
 Name
space for channels
 TIBCO
et al. use hierarchical directory
structure
 Caching
prior messages
 Subscribe
should spawn a thread that
sends previous N messages
Copyright © 1998 Purple Technology, Inc
Design issues
 Maintain
local cache of data sent
 Don’t
want to go back across the network
every time you draw a graph
 Create local version of class
Copyright © 1998 Purple Technology, Inc
Part IV: Advanced Topics
Copyright © 1998 Purple Technology, Inc
Exceptions
CORBA exceptions are mapped to Java
exceptions
 System Exceptions

 They’re
subclasses of RuntimeException, so the
compiler won’t complain if you forget to catch
them
 Minor codes

additional information

vendor-specific :-(
 Completion
Status
Copyright © 1998 Purple Technology, Inc
Exceptions (cont.)

User Exceptions
 Generated
by idltojava
 Subclasses of Exception (declared)
Copyright © 1998 Purple Technology, Inc
Dynamic Invocation Interface
(DII)
CORBA is fully self-aware
 Methods for acquiring

 List
of all services
 List of known objects
 Interfaces of known objects
 Etc.
 Well-documented
elsewhere
Copyright © 1998 Purple Technology, Inc
Interface Repositories
 JavaIDL
clients do not typically need or
use an Interface Repository
 All of the needed type information is
available in the stubs or is resolved by
an object's server
 JavaIDL supports access to Interface
Repository information made available
by other CORBA object
implementations.
Copyright © 1998 Purple Technology, Inc
Implementation Repository
 contains
information that allows the
ORB to locate and activate
implementations of objects
 also store additional information
associated with implementations of
ORB objects.
 Debugging
information
 Administrative control
 Resource allocation
 Security
Copyright © 1998 Purple Technology, Inc
Value Objects
 CORBA 3.0
 Blobs
 Avoids
network latency of pass-byreference objects
Copyright © 1998 Purple Technology, Inc
RMI over IIOP
 In
Development
 Uses IIOP as transport protocol
 Uses Value Objects to pass Java
serialized objects
Copyright © 1998 Purple Technology, Inc
CORBA via RMI
 Possible
using middleware server
 RMI from client to middleware
 IIOP from middleware to other servers
 Can use Servlet as middleware
Copyright © 1998 Purple Technology, Inc
CORBA and EJB
 Transport
 EJB
uses RMI interface, RMI uses IIOP
 CORBA 3.0
promises object
compatibility with EJB
 Not
quite sure what that means
 Some
 All
EJB Servers contain an ORB
EJB Objects are also CORBA objects
Copyright © 1998 Purple Technology, Inc
CORBA and EJB (Cont.)
 All
EJB Servers use CORBA
Transactions (via JTS)
 That
means that any client can make a
distributed transaction that includes both
CORBA and EJB Objects
 Not
an either-or decision
 You
can have both EJB and CORBA
working together in a single system
Copyright © 1998 Purple Technology, Inc
Java Transactions
 Java
Transaction Service (JTS)
 A standard
Java mapping of the OMG
Object Transaction Service (OTS)
 packages
org.omg.CosTransaction and
org.omg.CosTSPortability
 Java
Transaction API (JTA)
 High-level
transaction management
specification
 package
javax.transaction
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Object Transaction Service
(OTS)
 Distributed
 Part
transaction specification
of CORBA, but also standalone
 Transactions
can span
 multiple
queries
 multiple
objects
 multiple
servers
 multiple
databases
 multiple
vendors’ products
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OTS Features
 Distributed
 Flat
transactions
or nested transactions
 Two-phase
 Vendor
commit
interoperability (?)
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OTS Object Model
 Transactional
 Can
Object
participate in a transaction
 Recoverable
Object
 Actually
performs commit or rollback on its
own data
 Resource
 A system
or server that can commit or
rollback data stored inside it
 E.g.
a database server
Copyright © 1998 Purple Technology, Inc
OTS Object Model (Cont.)

Current
 Reference/wrapper


to currently active transaction
Control / Coordinator / Terminator
 Registers
objects
 Performs
distributed commit/rollback
Synchronization
 An
object that gets informed of the progress of the
ongoing transaction
 Implements
callback methods
Copyright © 1998 Purple Technology, Inc
Part V: CORBA/Java Case
Studies
Copyright © 1998 Purple Technology, Inc.
CORBA Case Study
 Kaiser
Permanente Northern California
 KAHUNA a/k/a WebChart
 http://www.javaworld.com/jw-111998/jw-11-kaiser.html?101698txt
Copyright © 1998 Purple Technology, Inc
Problem: Specific
 Medical
records, patient histories,
clinical schedules, lab results, and
medical images all stored in disparate
databases
 Many
patients per doctor, many doctors
per patient
 Need
immediate access to all
information
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Problem: General
 getting
data
 from
a multitude of sources
 in a multitude of media
 putting
 into
data
a single system
 distributing
data
 to
a wide variety of desktops
 throughout a very large company
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Solution: Java/CORBA
 “Not
only did Java/CORBA solve all
these problems, but Java/CORBA
development is cheap, fast, scalable
and works over the Internet.”
Copyright © 1998 Purple Technology, Inc
WebChart Architecture
Copyright © 1998 Purple Technology, Inc
This is your brain on Java.
Any questions?
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Conclusion
Copyright © 1998 Purple Technology, Inc.
Where to Get More
Information
 Orfali
& Harkey, Client/Server Programming with
Java and CORBA (Wiley)
 Orfali, Harkey & Edwards, Instant CORBA (Wiley)
Copyright © 1998 Purple Technology, Inc
More Info: Links
 This

http://www.purpletech.com/
 JDK

Presentation
1.2 CORBA documentation
http://java.sun.com/products/jdk/1.2/docs/guide/idl/
 Glerum,
WebChart serves up Kaiser patients,
JavaWorld

http://www.javaworld.com/jw-11-1998/jw-11kaiser.html?101698txt
Copyright © 1998 Purple Technology, Inc
More Info: Links
 Object
Management Group - http://www.omg.org
 Java Transactions
http://java.sun.com/products/jta/
 http://java.sun.com/products/jts/
 ftp://www.omg.org/pub/docs/formal/97-12-17.pdf

Copyright © 1998 Purple Technology, Inc