1. CORBA Technologies and Beyond
Nanbor Wang Tech-X Corporation Boulder, CO
ORNL-IU Workshop on Computational Framework in Fusion, Oak Ridge, TN, June 8, 2005

2. Outlines Overview of CORBA Applications Domain-Specific Services
CORBA Object Model
Interface Definition Language
Portable Object Adapter
Common Object Services
Domain-specific QoS concerns
CORBA application domains
CORBA-NG – CORBA Component Model (CCM)
New paradigm for application development
Component Implementations Definition Language
Application assembling, packaging, deployment and configuration
CCM application domains
Beyond CORBA
Scientific computation
Distributed and Parallel High-Performance Computing
Synergy with Common Component Architecture
Hardware
Domain-Specific
Services
Common
Middleware Services
Distribution
Middleware
Host Infrastructure
Operating Systems
& Protocols
Applications

3. Driving Force of CORBA
RTP
DNS
HTTP
UDP
TCP IP
TELNET
Ethernet
ATM
FDDI
Fibre Channel
FTP
INTERNETWORKING ARCH
TFTP
Win2K
Linux
LynxOS
Solaris
VxWorks
Middleware
Services
Applications
MIDDLEWARE ARCH
Traditional programming paradigm for distributed applications
Socket, RPC
Developers implement all aspects of applications
Distributed middleware abstracts away many aspects of using remote and local objects
Provide a foundation for higher-level services
CORBA is an OMG specification, there are many implementations

4. CORBA Object Model Location transparency, language interoperability
Parameter marshaling/demarshaling
Connection management
Object activation
Making client simple

5. Interface Definition Language
Separate interface and implementation
External view of objects (as interfaces)
Interface Echo {
string echo_string (in string message); };
Well-documented standard types
Interface, module, sequence, array, struct, enum, valuetype, etc.
IDL compiler generates object proxies and server skeletons
Mappings for “common” languages
C, C++, Java, Ada, Perl/Python, etc.
Memory management rules

6. Portable Object Adapter
Demultiplex incoming invocations
Act as a policy management domain
Standardize server configuration interfaces
Enable portable object implementations (servants)
Object activation strategies
Object reference lifecycle
Sharing an object implementation among multiple instances

7. Common Object Services
Services common for building applications of various domains
Naming Service – white page directory service
Trading Service – yellow page directory service
Messaging Service – asynchronous method invocation standard
Event/Notification Service – Flexible publisher/subscriber-based broadcasting mechanisms
Security Service – secure communication and access authorization, firewall traversal specification
Transaction Service – atomic execution of a series of operations
A/V Streaming Service – Managing A/V data streams
GPS
IFF
FLIR
HUD
Nav
WTS
Air Frame
Publishers
Subscribers
push(event)
Event Channel

8. Domain-Specific QoS Real-time CORBA Fault-tolerant CORBA
Static and dynamic scheduling
Custom transport protocol
Fault-tolerant CORBA
Fault detection, fail-over and recovery through redundancy
Load-Balancing CORBA
Load sharing using multiple object instances
Minimum CORBA
Small footprint applications
Portable interceptor standard
Injecting non-functional behaviors
Local interface

9. CORBA Application Domains
Joint Forces
Global Info Grid
Enterprise/civil applications
Financial apps
Real-time stock trading
Workflow planning
Embedded controllers
Air-traffic control
Military applications
Network-centric warfare/operation
Logistic planning
3C (Communication, command and control)
On-board computers

10. CORBA Application Domains (cont.)
Scientific community
Accelerator control and data acquisition
NASA space projects
Medical Imaging
Modalities
e.g., MRI, CT, CR, Ultrasound, etc.

11. Real-time Avionic Applications
Challenges
Real-time periodic processing
Complex dependencies
Very low latency

12. Global PCS Applications
Challenges
Long latency satellite links
High-reliability
Prioritization

13. Software Design Abstractions for Large-scale Distributed Applications
Problem
Distributed app & middleware functionality is subject to change since it’s often reused in unforeseen contexts, e.g.,
Accessed from different clients
Run on different platforms
Configured into different run-time contexts
MIDDLEWARE
Solution
Don‘t structure distributed applications & middleware as a monolithic spagetti
Instead, decompose them into modular classes, frameworks, & components

14. New Paradigm for Application Development
CORBA 2.x defines interfaces & policies, but not implementations
Separation of apps development concerns
Component Server
Component Implementation Framework
Deployment and Configuration
Composing rather than programming applications
Container
COMPONENT
EXECUTORS
Component
Home
POA
Transaction
Security
Notification
Persistent
Callback
Interfaces I n t e r a l f c s E v S i k F R p o u
Reference C m x
COMPONENT SERVER 1
COMPONENT SERVER 2
ORB

15. CORBA Component Ports A CORBA component can contain ports:
Facets (provides)
Offers operation interfaces
Receptacles (uses)
Required operation interfaces
Event sources (publishes & emits)
Produced events
Event sinks (consumes)
Consumed events
Attributes (attribute)
Configurable properties
Each component instance is created & managed by a unique component home
“Receives From”
“Sends To”

16. Component Implementation Definition Language (CIDL)
Automate certain server implementations
Introspection
Collaboration with container
Object lifecycle management
Connection management
Configuration mechanisms
Component

17. Assembling and Packaging
Assembling tools
Describe how to interconnect components into applications
Component packaging tools
Compose implementation & configuration information into deployable assemblies

18. Deployment and Configuration
Component deployment tools
Automate the deployment of component assemblies to component servers
Reconcile application needs with deployment target

19. CCM Application Domains
Component Server
Rate Generator
Avionics example used throughout tutorial as typical DRE application
Positioning Sensor
Display Device
$CIAO_ROOT/examples/OEP/Display/
Civil applications
Logistic management
ATC
Military applications
DARPA ARMS projects
On-board computer
Scientific applications ?

20. Beyond CORBA
CCM enables application modeling using higher-level abstractions (GUI modeling)
Scientific computational needs
Support for FORTRAN
Performance for tightly-coupled, collocated modules
Support for MPI and parallel execution of modules
Common Component Architecture addresses many of these insufficiencies
Combined distributed and parallel paradigms

21. Motivations for Mixing Distributed Tech. and Parallelism
Provide higher abstractions for HPC infrastructure
Motivating example scenarios:
Provide a different paradigm for partitioning problems – multi-physics simulations
Combine computing resources of multiple clusters/computing centers
Provide better utilization of high-CPU number hardware
Enable parallel data streaming between computing task and post-processing task

22. Remoting CCA Components
Support distributed computation by composing remote-capable components into an applications efficiently
Hide the distributed aspect from the localized CCA framework
Provide low-cost mechanisms for connecting uncompatible CCA infrastructures, e.g., Ccafeine, Dune, Ccain, and SciRUN

23. Deploying and Assembling DPHPC Applications
Local-CCA component centric view:
Local applications
Employ a distributed “builder service” for registering/requesting distributed ports
Distributed component centric view:
Two-tier deployment – remote components and their implementations
Grid view:
Making distributed components as grid services

24. Relevant Projects Fusion Data Grid Project:
Efficient access of local and remote fusion data in different formats (HDF5 and MDS+) via a unified interface
Binding for C/C++ and various viz/data analysis tools (IDL)
Fusion Simulation Markup Language
Metadata for annotating fusion simulation data
Semantic-based data access interface for structured and unstructured data
Binding for various viz/data analysis tools (AVS and IDL)
Data interpolation

25. Concluding Remarks
CORBA is a mature technology for distributed application development
CCM offers a higher-abstraction for large-scale distributed application development
CORBA and friends do not sufficiently address HPC parallel application needs (many CCA implementations do)
Looking forward:
Providing distributed and parallel high-performance computing environment allows integrating existing codes using higher abstractions
Combining CORBA and CCA takes advantage of well-established technologies
Hardware
Domain-Specific
Services
Common
Middleware Services
Distribution
Middleware
Host Infrastructure
Operating Systems
& Protocols
Applications

26. Questions