Corba and QuO

1
Corba and QuO

• Announcements/Review
• Projects Writeup Handout out today
• Planned Guest Lectures
• 3/9 Netsolve (Henri Casanova)
• 3/11 Data Intensive Applications (Reagan Moore)
• Last Time
• Course Project Coordination

2
Todays Outline

• Corba 2
• IDL, IIOP
• Additional Services
• Java/Corba Integration
• Object Web -- merging of the web and ORBs
• Adding Quality of Service

3
Beyond RPC gt Corba

• RPC enables
• Remote interaction with procedure call model
• Management of heterogeneity / interoperation
• Distributed Objects associate Data with the
  procedure calls
• Invocation on an object (with state)
• Procedure implementation defined by the object
  (polymorphism / object orientation)
• How do we make this work?
• At the start of the OMG (1991?), many diverse
  distributed object models.

4
Common Object Request Broker Architecture

• Define a standard set of interfaces
  (client-server)
• Define a standard IDL (data description)
• Define language bindings (C, C, Ada, Cobol,
  etc.)
• Enable the construction of orbs which would allow
  these things to interoperate
• gt these concepts are the core of the other
  systems weve discussed (ejb, dcom)

5
Corba 1.1 (1992)

• Basic ORB
• Basic Object Adapter (BOA)
• C bindings
• Naming
• Events
• Life cycle
• Persistence

6
Generalize platform standardize, standardize,
standardize...

• Corba 2.0 (1995)
• IIOP
• C Bindings
• Transactions
• Concurrency
• Compound documents
• Security
• Time
• .

7
Corba is a work in progress

• Corba 2.2 is standard now, 2.3 in the works,
  Corba Component spec in the works (several
  proposals)
• Messaging (MoM)
• POA (server portability)
• Java Beans, EJB, Objects-by-value
• Corba/DCOM
• Mobile Agents
• Automatice Persistence
• IIOP Firewall support
• Workflow
• Domain level frameworks

8
High Performance Distributed Computing

• Support for Quality of Service?
• Support for Real Time?
• Support for high performance?

9
Java/Corba Marriage

• Shotgun wedding pushed by the gang of four
• IBM, Netscape, Oracle, Sun
• Integrate Java Beans and Corba
• Enable integration of web and Corba, Object Web
• Product is Enterprise Java Beans (and the IIOP
  and Corba IDL integration present there)
• Who swallowed whom? Alignment vs. DCOM

10
Motivation the Object Web

• Applet Model (present or past?)
• download, connect back to server
• launch server computations via CGI-BIN
• Problems
• slow launch, expensive
• how to get to other services?

11
Object Web
http
iiop
corba

• Integrate http and iiop
• http -gt corba client
• active objects in web page, corba invocations for
  server interactions
• generalize security model
• entrée to multiple server interactions?

12
Discussion

• What kinds of capabilities does this enable?
• What kinds of problems does it raise?
• Can you generalize this model to get beyond
  client server to multiparty?
• How does this relate to high performance
  distributed computing applications?

13
Corba and Evolution

• Corba as a federation infrastructure for
  distributed objects
• Corba as a distributed platform (w/ many
  services)
• Corba merging with Java as a distributed platform

14
BBN QuO Project

• Motivation
• Most distributed applications (e.g. Corba)
  developed without regard for wide area issues
• Most distributed application programmers dont
  deal with with these conditions
• IDL hides many of the issues about this (dont
  see the distribution directly)
• Dealing with this in current Corba makes it hard
  to reuse solutions to these problems.
• Solution
• Add Quality of Service Annotations for Corba
  Objects

15
QUality of service for Objects

• Describe quality of service for Corba objects,
  make these first class entities, kept with the
  functional software and interfaces
• Reduce the variance of these qualities by masking
  (?)
• Documents the key decisions (assumptions) of an
  objects design
• Make them reusable
• gt add a QDL Quality Description Language for
  the interfaces to objects
• gt used for instantiation, monitoring, and
  management
• gt documents the design assumptions, can reuse
  code around similar QDL

16
Three Part System

• Add QDL description at interface
• latency, bandwidth, jitter
• availability, etc.
• Add monitoring interface
• check that quality is met
• Add adaptation interface
• failure to meet spec triggers callback mechanism
• system or application level management to
  reconfigure
• gt how to adapt is an open area of research.

17
Readings

• Today
• Object Management Group, Corba 2.2 Specification
  (available from www.omg.org)
• Orfali and Harkey, Client/Server Programming with
  Java and Corba, J. Wiley and Sons.
• Corbus http//www.bbn.com/products/dpom/dualuse.h
  tm
• QuO http//www-csag.ucsd.edu/teaching/cse225-w99/
  papers/quotapos.ps and quotapos.pdf