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CCA

Common Component Architecture

CCA Forum Tutorial Working Group

http://www.cca
-
forum.org/tutorials/

tutorial
-
wg@cca
-
forum.org

1

Welcome to the

Common Component Architecture

Tutorial

SIAM PP04

28 February 2004

CCA

Common Component Architecture

2

Agenda & Table of Contents

Time

Title

Slide
No.

Presenter

8:30
-
8:35am

Welcome

1

Gary Kumfert, LLNL

8:35
-
9:15am

Introduction to Components

8

Gary Kumfert, LLNL & Lois
Curfman McInnes, ANL

9:15
-
10:00am

CCA Concepts

53

Lois Curfman McInnes, ANL

10:00
-
10:30am

Break

10:30
-
11:30am

Language Interoperability with Babel

85

Gary Kumfert, LLNL

11:30am
-
12:30pm

A Look at More Complex CCA
Applications

121

Jaideep Ray, SNL

12:30
-
1:30pm

Lunch

1:30
-
2:00pm

A Simple CCA Example

164

Rob Armstrong, SNL

2:00
-
2:45pm

Writing CCA Components

183

Rob Armstrong, SNL

2:45
-
3:30pm

Using Ccaffeine

221

Rob Armstrong, SNL

3:30
-
4:00pm

Break

4:00
-
4:30pm

CCA Status and Plans

246

Jaideep Ray, SNL

4:30pm
-
?

One
-
on
-
one discussions and hands
-
on using own Linux laptop

All

CCA

Common Component Architecture

3

Who Are We?

(And Where Did We Come From?
)


ACTS Toolkit Interoperability Effort (Late 1990’s)


Part of DOE 2000, Many Tool Integration Projects


“One
-
to
-
One”, Leading to N
2

Solutions…



Common Component Architecture Forum (1998)


Goal: To Develop a General Interoperability Solution


Grass Roots Effort to Explore High
-
Performance
Components for Scientific Software


SciDAC Center for Component Technology for
Terascale Simulation Software (CCTTSS, 2001)


Part of New DOE Scientific Simulation Program


Technology Development in Several Thrust Areas…

CCA

Common Component Architecture

4

The Common Component Architecture

(CCA) Forum


Define Specifications for
High
-
Performance

Scientific
Components & Frameworks


Promote and Facilitate Development of Domain
-
Specific
“Standard” Interfaces


Goal:
Interoperability

between components developed
by different expert teams across different institutions


Quarterly Meetings, Open membership…

http://www.cca
-
forum.org/

Mailing List:
cca
-
forum@cca
-
forum.org

CCA

Common Component Architecture

5

Center for Component Technology for
Terascale Simulation Software (CCTTSS)


DOE SciDAC ISIC ($16M over
5 years)


SciDAC = Scientific Discovery
through Advanced Computing


ISIC = Integrated Software
Infrastructure Center


Funded by Office of
Mathematical, Information and
Computational Sciences
(MICS)


Develop CCA technology from
current prototype stage to full
production environment


Increase understanding of how
to use component architectures
effectively in HPC environments


Subset of CCA Forum


Participants: ANL, LLNL, LANL,
ORNL, PNNL, SNL, Indiana
University, University of Utah


Lead PI: Rob Armstrong, SNL
rob@sandia.gov


http://www.cca
-
forum.org/ccttss/

CCA

Common Component Architecture

6

CCTTSS Research Thrust Areas

and Main Working Groups


Scientific Components


Scientific Data Objects

Lois Curfman McInnes, ANL (curfman@mcs.anl.gov)


“MxN” Parallel Data Redistribution

Jim Kohl, ORNL (kohlja@ornl.gov)


Frameworks


Language Interoperability / Babel / SIDL


Component Deployment / Repository

Gary Kumfert, LLNL (kumfert@llnl.gov)


User Outreach

David Bernholdt, ORNL (bernholdtde@ornl.gov)

CCA

Common Component Architecture

7

Acknowledgements


CCA Forum Tutorial WG


Rob Armstrong, David Bernholdt, Wael Elwasif, Lori Freitag, Dan Katz,
Jim Kohl, Gary Kumfert, Lois Curfman McInnes, Boyana Norris, Craig
Rasmussen, Jaideep Ray, Sameer Shende, Torsten Wilde, Shujia Zhou


ANL, JPL, LANL, LLNL, NASA/Goddard, ORNL, SNL, U Oregon


And many more contributing to CCA itself…


ANL


Lori Freitag Diachin, Kate Keahey, Jay Larson, Ray Loy, Lois
Curfman McInnes, Boyana Norris, …


Indiana University
-

Randall Bramley, Dennis Gannon, …


JPL


Dan Katz, …


LANL
-

Craig Rasmussen, Matt Sotille, …


LLNL


Lori Freitag Diachin, Tom Epperly, Scott Kohn, Gary Kumfert, …


NASA/Goddard


Shujia Zhou


ORNL
-

David Bernholdt,
Wael Elwasif,

Jim Kohl, Torsten Wilde, …


PNNL
-

Jarek Nieplocha, Theresa Windus, …


SNL
-

Rob Armstrong, Ben Allan, Lori Freitag Diachin, Curt Janssen,
Jaideep Ray, …


University of Oregon


Allen Malony, Sameer Shende, …


University of Utah
-

Steve Parker, …


And others as well …

CCA

Common Component Architecture

CCA Forum Tutorial Working Group

http://www.cca
-
forum.org/tutorials/

tutorial
-
wg@cca
-
forum.org

8

A Pictorial Introduction

to Components

in Scientific Computing

CCA

Common Component Architecture

9

Once upon a time...

Input

Output

Program

CCA

Common Component Architecture

10

As Scientific Computing grew...

CCA

Common Component Architecture

11

Tried to ease the bottle neck

CCA

Common Component Architecture

12

SPMD was born.

2

1

3

4

2

1

3

4

2

1

3

4

CCA

Common Component Architecture

13

SPMD worked.

2

1

3

4

2

1

3

4

2

1

3

4

But it

isn’t

easy!!!

But it

isn’t

easy!!!

CCA

Common Component Architecture

14

Meanwhile, corporate computing was growing
in a different way

Input

Output

Program

browser

spreadsheet

editor


graphics

database

multimedia

email client

Unicode

Input

CCA

Common Component Architecture

15

This created a whole new set of problems
complexity

browser

spreadsheet

editor


graphics

database

multimedia

email client

Unicode


Interoperability across
multiple languages


Interoperability across
multiple platforms


Incremental evolution of
large legacy systems
(esp. w/ multiple 3rd
party software)

CCA

Common Component Architecture

16

Component Technology

addresses these problems

CCA

Common Component Architecture

17

So what’s a component ???

Implementation :

No Direct Access

Interface Access :

Generated by Tools

Matching Connector :

Assigned by Framework

Hidden from User

CCA

Common Component Architecture

18

1. Interoperability across


multiple languages

C

C++

F77

Java

Language &

Platform

independent

interfaces

Automatically

generated

bindings to

working code

CCA

Common Component Architecture

19

2. Interoperability Across Multiple


Platforms

Imagine a company
migrates to a new
system, OS, etc.

What if the
source to
this one part
is lost???

CCA

Common Component Architecture

20

Transparent Distributed Computing

internet

internet

These wires

are very,

very smart!

CCA

Common Component Architecture

21

3. Incremental Evolution With


Multiple 3rd party software

v 1.0

v 2.0

v 3.0

CCA

Common Component Architecture

22

Now suppose you find this bug...

v 1.0

v 2.0

v 3.0

CCA

Common Component Architecture

23

Good news: an upgrade available


v 1.0

v 2.0

v 3.0

Bad news: there’s a dependency


2.1

2.0

CCA

Common Component Architecture

24

v 3.0


2.1

2.0



Great News:

Solvable with Components

CCA

Common Component Architecture

25

v 1.0

Great News:

Solvable with Components


2.1

v 3.0

2.0

CCA

Common Component Architecture

26

Why Components for Scientific Computing
Complexity


Interoperability across
multiple languages


Interoperability across
multiple platforms


Incremental evolution of
large legacy systems
(esp. w/ multiple 3rd
party software)

Sapphire

SAMRAI

Ardra


Scientific Viz

DataFoundry

Overture

linear solvers

hypre

nonlinear solvers

ALPS

JEEP

CCA

Common Component Architecture

27

The Model for Scientific Component
Programming

Science

Industry

?

CCA

CCA

Common Component Architecture

CCA Forum Tutorial Working Group

http://www.cca
-
forum.org/tutorials/

tutorial
-
wg@cca
-
forum.org

28

Components for Scientific Computing:
An Introduction

CCA

Common Component Architecture

29

Goals of This Module


Introduce basic
concepts and vocabulary

of
component
-
based software engineering


Highlight the special
demands of high
-
performance
scientific computing

on component environments


Provide a
unifying context

for the remaining talks


And to consider what components might do for your
applications

CCA

Common Component Architecture

30

Motivation: Modern Scientific Software
Engineering Challenges


Productivity


Time to first solution (prototyping)


Time to solution (“production”)


Software infrastructure requirements (“other stuff needed”)


Complexity


Increasingly sophisticated models


Model coupling


multi
-
scale, multi
-
physics, etc.


“Interdisciplinarity”


Performance


Increasingly complex algorithms


Increasingly complex computers


Increasingly demanding applications

CCA

Common Component Architecture

31

Motivation: For Library Developers


People want to use your software, but need wrappers
in languages you don’t support


Many component models provide language interoperability


Discussions about standardizing interfaces are often
sidetracked into implementation issues


Components separate interfaces from implementation


You want users to stick to your published interface
and prevent them from stumbling (prying) into the
implementation details


Most component models actively enforce the separation

CCA

Common Component Architecture

32

Motivation: For Application Developers
and Users


You have difficulty managing
multiple third
-
party
libraries

in your code


You (want to) use
more than two languages

in your
application


Your code is
long
-
lived

and different pieces
evolve

at
different rates


You want to be able to
swap

competing
implementations of the same idea and
test
without
modifying any of your code


You want to
compose

your application with some
other(s) that weren’t originally designed to be
combined

CCA

Common Component Architecture

33

Some Observations About Software…


“The complexity of software is an essential
property, not an accidental one.”
[Brooks]


We can’t get rid of complexity


“Our failure to master the complexity of
software results in projects that are late, over
budget, and deficient in their stated
requirements.”
[Booch]


We must find ways to manage it

CCA

Common Component Architecture

34

More Observations…


“A complex system that works is invariably
found to have evolved from a simple system
that worked… A complex system designed
from scratch never works and cannot be
patched up to make it work.”
[Gall]


Build up from simpler pieces


“The best software is code you don’t have to
write”
[Jobs]


Reuse code wherever possible

CCA

Common Component Architecture

35

Not All Complexity is “Essential”


An example of how typical development practices can
exacerbate the complexity of software development…


At least 41 different Fast Fourier Transform (FFT)
libraries:


see, http://www.fftw.org/benchfft/doc/ffts.html


Many (if not all) have different interfaces


different procedure names and different input and output
parameters


Example: SUBROUTINE FOUR1(DATA, NN, ISIGN)


“Replaces DATA by its discrete Fourier transform (if ISIGN is
input as 1) or replaces DATA by NN times its inverse discrete
Fourier transform (if ISIGN is input as
-
1). DATA is a complex
array of length NN or, equivalently, a real array of length 2*NN.
NN MUST be an integer power of 2 (this is not checked for!).”

CCA

Common Component Architecture

36

Component
-
Based Software
Engineering


CBSE methodology is emerging, especially from business
and internet areas


Software productivity


Provides a “
plug and play
” application development environment


Many components available “off the shelf”


Abstract interfaces facilitate
reuse and interoperability

of software


Software complexity


Components
encapsulate

much
complexity

into “black boxes”


Plug and play approach simplifies applications


Model coupling

is natural in component
-
based approach


Software performance
(indirect)


Plug and play approach and rich “off the shelf” component library
simplify changes to
accommodate different platforms

CCA

Common Component Architecture

37

A Simple Example:

Numerical Integration Components

FunctionPort

MidpointIntegrator

IntegratorPort

FunctionPort

MonteCarloIntegrator

IntegratorPort

RandomGeneratorPort

IntegratorPort

Driver

GoPort



NonlinearFunction

FunctionPort



LinearFunction

FunctionPort



RandomGenerator

RandomGeneratorPort



PiFunction

FunctionPort

Interoperable components
(provide same interfaces)

CCA

Common Component Architecture

38

FunctionPort

MidpointIntegrator

IntegratorPort

FunctionPort

MonteCarloIntegrator

IntegratorPort

RandomGeneratorPort

IntegratorPort

Driver

GoPort



NonlinearFunction

FunctionPort



LinearFunction

FunctionPort



RandomGenerator

RandomGeneratorPort



PiFunction

FunctionPort

An Application

Built from the Provided Components

Hides compexity: Driver
doesn’t care that
MonteCarloIntegrator
needs a random
number generator

CCA

Common Component Architecture

39

Another Application…

FunctionPort

MidpointIntegrator

IntegratorPort

FunctionPort

MonteCarloIntegrator

IntegratorPort

RandomGeneratorPort

IntegratorPort

Driver

GoPort



NonlinearFunction

FunctionPort



LinearFunction

FunctionPort



RandomGenerator

RandomGeneratorPort



PiFunction

FunctionPort

CCA

Common Component Architecture

40

Application 3…

FunctionPort

MidpointIntegrator

IntegratorPort

FunctionPort

MonteCarloIntegrator

IntegratorPort

RandomGeneratorPort

IntegratorPort

Driver

GoPort



NonlinearFunction

FunctionPort



LinearFunction

FunctionPort



RandomGenerator

RandomGeneratorPort



PiFunction

FunctionPort

CCA

Common Component Architecture

41

And Many More…

FunctionPort

MidpointIntegrator

IntegratorPort

FunctionPort

MonteCarloIntegrator

IntegratorPort

RandomGeneratorPort

IntegratorPort

Driver

GoPort



NonlinearFunction

FunctionPort



LinearFunction

FunctionPort



RandomGenerator

RandomGeneratorPort



PiFunction

FunctionPort

Dashed lines
indicate alternate
connections

Create different applications
in "plug
-
and
-
play" fashion

CCA

Common Component Architecture

42

What
are

Components?


No universally accepted definition…yet


A unit of software development/deployment/reuse


i.e. has
interesting functionality


Ideally, functionality someone else might be able to (re)use


Can be
developed independently

of other components


Interacts with the outside world
only

through well
-
defined interfaces


Implementation is opaque

to the outside world


Components
may

maintain state information


But external access to state info must be through an interface (
not a
common block
)


File
-
based interactions can be recast using an “I/O component”


Can be composed with other components


“Plug and play” model to build applications


Composition based on interfaces

CCA

Common Component Architecture

43

What is a Component Architecture?


A set of
standards

that allows:


Multiple groups to write units of software (
components
)…


And have confidence that their components will
work with
other components

written in the same architecture


These standards
define



The rights and responsibilities of a
component


How components express their
interfaces


The environment in which are composed to form an
application and executed (
framework
)


The rights and responsibilities of the framework

CCA

Common Component Architecture

44

Interfaces, Interoperability, and Reuse


Interfaces define how components interact…


Therefore interfaces are key to interoperability and
reuse of components


In many cases, “any old interface” will do, but…


General plug and play interoperability requires
multiple implementations

providing the same
interface


Reuse of components occurs when they provide
interfaces (functionality) needed in
multiple
applications

CCA

Common Component Architecture

45

Designing for Reuse, Implications


Designing for interoperability and reuse requires
“standard” interfaces


Typically domain
-
specific


“Standard” need not imply a formal process, may mean
“widely used”


Generally means
collaborating

with others


Higher

initial development cost (
amortized over
multiple uses
)


Reuse implies
longer
-
lived code


thoroughly tested


highly optimized


improved support for multiple platforms

CCA

Common Component Architecture

46

Relationships:

Components, Objects, and Libraries


Components are typically discussed as
objects

or
collections of objects


Interfaces

generally designed in
OO

terms, but…


Component
internals need not be OO


OO languages are not required


Component environments can
enforce

the use of
published interfaces
(prevent access to internals)


Libraries can not


It is possible to load
several instances

(versions) of a
component in a single application


Impossible with libraries


Components
must

include some code to
interface
with the framework/component environment


Libraries and objects do not

CCA

Common Component Architecture

47

Domain
-
Specific Frameworks vs
Generic Component Architectures

Domain
-
Specific


Often known as
“frameworks”


Provide a significant
software infrastructure to
support applications in a
given domain


Often attempts to generalize
an existing large application


Often hard to adapt to use
outside the original domain


Tend to assume a
particular
structure/workflow

for
application


Relatively
common

Generic


Provide the infrastructure to
hook components

together


Domain
-
specific
infrastructure can be built as
components


Usable in
many domains


Few assumptions about
application


More opportunities for reuse


Better supports
model
coupling

across traditional
domain boundaries


Relatively
rare

at present


Commodity component
models often not so useful
in HPC scientific context

CCA

Common Component Architecture

48

Special Needs of Scientific HPC


Support for legacy software


How much
change
required for component environment?


Performance is important


What
overheads

are imposed by the component
environment?


Both parallel and distributed computing are important


What approaches does the component model support?


What
constraints

are imposed?


What are the
performance costs
?


Support for
languages, data types, and platforms


Fortran?


Complex numbers? Arrays? (as first
-
class objects)


Is it available on my parallel computer?

CCA

Common Component Architecture

49

Commodity Component Models


CORBA, COM, Enterprise JavaBeans


Arise from business/internet software world


Componentization
requirements

can be
high


Can impose significant
performance overheads


No recognition of
tightly
-
coupled parallelism


May be
platform specific



May have
language constraints


May not support common scientific
data types

CCA

Common Component Architecture

50

The “Sociology” of Components


Components need to be
shared

to be truly useful


Sharing can be at several levels


Source, binaries, remote service


Various models possible for
intellectual property/licensing


Components with different IP constraints can be
mixed in a
single application


Peer component models facilitate
collaboration

of
groups on software development


Group decides overall
architecture

and
interfaces


Individuals/sub
-
groups create individual
components

CCA

Common Component Architecture

51

Who Writes Components?


“Everyone” involved in creating an application
can/should create components


Domain scientists

as well as
computer scientists

and
applied
mathematicians


Most will also use components written by other groups


Allows developers to
focus

on their interest/specialty


Get other capabilities via
reuse

of other’s components


Sharing components within scientific domain allows
everyone to be
more productive


Reuse instead of reinvention


As a
unit of publication
, a well
-
written and

tested
component is like a high
-
quality library


Should receive same degree of recognition


Often a more appropriate unit of publication/recognition than
an entire application code

CCA

Common Component Architecture

52

Summary


Components are a software engineering tool to help
address software
productivity

and
complexity


Important concepts:
components, interfaces,
frameworks, composability, reuse


Scientific component environments come in “domain
specific” and “generic” flavors


Scientific HPC imposes
special demands

on
component environments


Which commodity tools may have trouble with

CCA

Common Component Architecture

CCA Forum Tutorial Working Group

http://www.cca
-
forum.org/tutorials/

tutorial
-
wg@cca
-
forum.org

53

Common Component Architecture
Concepts

CCA

Common Component Architecture

54

Goals


Introduce the
motivation

and essential
features

of the Common Component
Architecture


Provide
common vocabulary

for remainder of
tutorial


What distinguishes CCA from
other
component environments
?

CCA

Common Component Architecture

55

What is the CCA? (User View)


A component model specifically designed for
high
-
performance

scientific computing


Minimalist

approach makes it easier to componentize
existing software


A
tool

to enhance the productivity of scientific
programmers


Make the hard things easier, make some intractable things
tractable


Support & promote reuse & interoperability


Not a magic bullet

CCA

Common Component Architecture

56

What is the CCA? (Technical View)


CCA is a
specification

of a component environment


A design pattern


Defines rights and responsibilities of a CCA
component


Defines how CCA components express their
interfaces


Defines rights and responsibilities of a CCA
framework



CCA compliant
” means conforming to the
specification


Doesn’t require using any of our code


CCA specification is decided by the
CCA Forum


Membership in the CCA Forum is
open to all

CCA

Common Component Architecture

57

CCA Concepts: Components


Components provide/use one or more
ports


A component with no ports isn’t very interesting


Components include some
code which
interacts with a CCA framework



NonlinearFunction

FunctionPort

FunctionPort

MidpointIntegrator

IntegratorPort

CCA

Common Component Architecture

58

CCA Concepts: Ports


Components interact through well
-
defined
interfaces
,
or
ports


In OO languages, a port is a
class

or
interface


In Fortran, a port is a bunch of subroutines or a
module


Components may
provide

ports


implement

the
class or subroutines of the port ( )


Components may
use

ports


call

methods or
subroutines in the port ( )


Links between ports denote a procedural
(caller/callee) relationship,
not dataflow!


e.g., FunctionPort could contain:
evaluate(
in

Arg,
out

Result)



NonlinearFunction

FunctionPort

FunctionPort

MidpointIntegrator

IntegratorPort

“Provides” Port

“Uses” Port

CCA

Common Component Architecture

59

CCA Concepts: Frameworks


The framework provides the means to “hold”
components and
compose

them into applications


Frameworks allow
connection of ports

without
exposing component implementation details


Frameworks provide a small set of
standard services

to components


Currently:

specific frameworks support specific
computing models (parallel, distributed, etc.)


Future:

full flexibility through integration or
interoperation

CCA

Common Component Architecture

60

Components and Ports

in the Integrator Example

FunctionPort

MidpointIntegrator

IntegratorPort

FunctionPort

MonteCarloIntegrator

IntegratorPort

RandomGeneratorPort

IntegratorPort

Driver

GoPort



NonlinearFunction

FunctionPort



LinearFunction

FunctionPort



RandomGenerator

RandomGeneratorPort



PiFunction

FunctionPort

Dashed lines
indicate alternate
connections

Create different applications
in "plug
-
and
-
play" fashion

CCA

Common Component Architecture

61

Writing Components


Components…


Inherit from
gov.cca.Component


Implement

setServices

method to register ports this
component will
provide

and
use


Implement the ports they provide


Use ports on other components


getPort/releasePort

from framework
Services

object


Interfaces (ports) extend
gov.cca.Port

Much

more detail later in the tutorial!

CCA

Common Component Architecture

62

Adapting Existing Code into
Components

Suitably structured code (programs, libraries) should be
relatively easy to adapt to the CCA. Here’s how:

1.
Decide
level of componentization


Can evolve with time (start with coarse components, later
refine into smaller ones)

2.
Define
interfaces

and write wrappers between them
and existing code

3.
Add
framework interaction code

for each component


setServices

4.
Modify component internals to
use other
components

as appropriate


getPort
,
releasePort

and method invocations

CCA

Common Component Architecture

63

Writing Frameworks


There is no reason for most people to write
frameworks


just use the existing ones!


Frameworks must provide certain ports…


ConnectionEventService


Informs the component of connections


AbstractFramework


Allows the component to
behave as a framework


BuilderService


Instantiate components & connect ports


ComponentRepository


A default place where components are found


Frameworks must be able to load components


Typically shared object libraries, can be statically linked


Frameworks must provide a way to compose
applications from components

CCA

Common Component Architecture

64

Component

Lifecycle


Composition Phase (assembling application)


Component is
instantiated

in framework


Component interfaces are
connected

appropriately


Execution Phase (running application)


Code in components uses functions provided by another
component


Decomposition Phase (termination of application)


Connections

between component interfaces may be
broken


Component may be
destroyed

In an application, individual components may be in
different phases at different times

Steps may be under human or software control

We’ll look at actual
code in next
tutorial module

CCA

Common Component Architecture

65

User Viewpoint:

Loading and Instantiating Components

create

Driver

Driver

create

LinearFunction

LinearFunction

create

MonteCarloIntegrator

MonteCarloIntegrator


Details are
framework
-
specific
!


Ccaffeine

currently provides both
command line and GUI approaches


Components are code +
metadata


Using metadata, a
Palette

of available components is
constructed


Components are
instantiated by user action
(i.e. by dragging from
Palette

into
Arena
)


Framework calls
component’s
constructor
,
then
setServices

CCA

Common Component Architecture

66

connect

Driver

IntegratorPort

MonteCarloIntegrator

IntegratorPort

connect

MonteCarloIntegrator

FunctionPort

LinearFunction

FunctionPort



User Connects Ports


Can only connect uses &
provides


Not uses/uses or
provides/provides


Ports connected by type, not
name


Port names must be unique
within component


Types must match across
components


Framework puts info about
provider
of port

into
using
component’s

Services object

CCA

Common Component Architecture

67

Composition Phase

Composition Phase

Framework Mediates
Most

Component Interactions

Integrator

Integrator code

getPort(Fun)

y=Fun(x)

releasePort(Fun)

Framework interaction code

constructor

setServices

destructor

CCA.Services

provides Result

uses Fun

LinearFunction

Function code

Fun(x) = 3 * x + 17

CCA.Services

provides Fun

Framework interaction code

constructor

setServices

destructor

1

2

1’

2’

3

5

4

6

Execution Phase

*

Method invocation need not
be mediated by the framework!

*

CCA

Common Component Architecture

68

Component’s View of Instantiation


Framework calls component’s
constructor


Component initializes internal
data, etc.


Knows
nothing

outside itself


Framework calls component’s
setServices


Passes setServices an object
representing everything “outside”


setServices declares ports
component
uses
and
provides


Component
still

knows nothing
outside itself


But Services object provides the
means of communication w/
framework


Framework now knows how to
“decorate” component and how it
might connect with others

FunctionPort

MonteCarloIntegrator

IntegratorPort

RandomGeneratorPort

MonteCarloIntegrator

Integrator code

Framework interaction code

constructor

setServices

destructor

CCA.Services

provides IntegratorPort

uses FunctionPort,
RandomGeneratorPort

CCA

Common Component Architecture

69

Component’s View
of Connection


Framework puts info
about provider into
user
component’s

Services
object


MonteCarloIntegrator
’s
Services object is aware
of connection


NonlinearFunction

is
not!


MCI
’s integrator code
cannot yet call functions
on FunctionPort

NonlinearFunction

Function code

CCA.Services

provides FunctionPort

Framework interaction code

MonteCarloIntegrator

Integrator code

Framework interaction code

CCA.Services

…, uses FunctionPort


(connected to NonlinearFunction
FunctionPort), …

CCA

Common Component Architecture

70

Component’s View of Using a Port

MonteCarloIntegrator

Integrator code

Framework interaction code

CCA.Services

…, uses FunctionPort


(connected to NonlinearFunction
FunctionPort), …


User calls
getPort

to obtain
(handle for) port from Services


Finally user code can “see”
provider


Cast
port to expected type


OO programming concept


Insures type safety


Helps enforce declared
interface


Call
methods on port


e.g.

sum = sum +
function
-
>evaluate(x)


Release

port

CCA

Common Component Architecture

71

CCA Supports Local, Parallel and
Distributed Computing



Direct connection
” preserves high
performance of local (“in
-
process”)
components


Framework makes
connection


But is not involved in
invocation


Distributed computing

has same
uses/provides pattern, but
framework intervenes

between user
and provider


Framework provides a
proxy

provides port local to the
uses

port


Framework conveys invocation
from proxy to actual provides port

Integrator

Linear Fun

Provides/Uses

Port

Direct Connection

Integrator

Linear Fun

Provides

Port

Network

Connection

Proxy
Provides/

UsesPort

CCA

Common Component Architecture

72

CCA Concepts: “Direct Connection”
Maintains Local Performance


Calls
between

components equivalent to a C++
virtual function call
: lookup function location, invoke it


Cost equivalent of
~2.8 F77 or C function calls


~48 ns vs 17 ns on 500 MHz Pentium III Linux box


Language interoperability

can impose additional
overheads


Some arguments require conversion


Costs vary, but small for typical scientific computing needs


Calls
within

components have
no CCA
-
imposed
overhead


Implications


Be aware of costs


Design so inter
-
component calls
do enough work

that
overhead is negligible

CCA

Common Component Architecture

73

How Does Direct Connection Work?


Components loaded into
separate
namespaces

in the
same
address

space (process) from shared libraries


getPort

call returns a pointer to the port’s function
table


All this happens “automatically”


user just sees high
performance


Description reflects
Ccaffeine

implementation, but similar or
identical mechanisms are in other direct connect fwks


Many CORBA implementations offer a similar
approach to improve performance, but
using it
violates the CORBA standards!

CCA

Common Component Architecture

74

CCA Concepts: Framework Stays “Out
of the Way” of Component Parallelism


Single component multiple data
(SCMD) model is component
analog of widely used SPMD
model

P0

P1

P2

P3

Components:
Blue
,
Green
,
Red

Framework:
Gray

MCMD/MPMD also supported


Different components in same
process “talk to each” other via
ports and the framework


Same component in different
processes talk to each other
through their favorite
communications layer (i.e.
MPI, PVM, GA)


Each process loaded with the
same set of components wired
the same way

Other component models
ignore parallelism entirely

CCA

Common Component Architecture

75

Scalability of Scientific Data Components
in CFRFS Combustion Applications


Investigators: S. Lefantzi, J. Ray,
and H. Najm (SNL)


Uses GrACEComponent,
CvodesComponent, etc.


Shock
-
hydro code with no
refinement


200 x 200 & 350 x 350 meshes


Cplant cluster


400 MHz EV5 Alphas


1 Gb/s Myrinet


Negligible component overhead


Worst perf : 73% scaling efficiency
for 200x200 mesh on 48 procs

Reference: S. Lefantzi, J. Ray, and H. Najm, Using the Common Component Architecture to Design High Performance
Scientific Simulation Codes,
Proc of Int. Parallel and Distributed Processing Symposium
, Nice, France, 2003.

CCA

Common Component Architecture

76


Simulation composed of multiple SCMD sub
-
tasks


Usage Scenarios:


Model coupling (e.g. Atmosphere/Ocean)


General multi
-
physics applications


Software licensing issues


Approaches


Run single parallel framework


Driver component that partitions processes and builds rest of
application as appropriate (through BuilderService)


Run multiple parallel frameworks


Link through specialized communications components (e.g. MxN)


Link as components (through AbstractFramework service; highly
experimental at present)

“Multiple
-
Component Multiple
-
Data”
Applications in CCA

Ocean

Atmosphere

Land

Driver

Coupler (MxN)

CCA

Common Component Architecture

77

Components only on
process group B

Group B

MCMD Within A Single Framework

Components on all
processes

Application driver & MCMD
support component

P0

P1

P2

P3

Framework

Components only on
process group A

Group A

Working examples available
using Ccaffeine framework,
with driver coded in Python

CCA

Common Component Architecture

78

CCA Concepts:

MxN Parallel Data Redistribution


Share Data Among Coupled Parallel Models



Disparate Parallel Topologies (M processes vs. N)



e.g. Ocean & Atmosphere, Solver & Optimizer…



e.g. Visualization (Mx1, increasingly, MxN)

Research area
--

tools under development

CCA

Common Component Architecture

79

CCA Concepts:

Language Interoperability


Existing language
interoperability
approaches are
“point
-
to
-
point”

solutions


Babel
provides a unified
approach in which all
languages are
considered
peers


Babel used primarily at
interfaces

C

C++

f77

f90

Python

Java

Babel

C

C++

f77

f90

Python

Java

Babel tutorial
coming up!

Few other component models support all languages
and data types important for scientific computing

CCA

Common Component Architecture

80

Performance Issues (Redux)


No CCA overhead on
calls within components


CCA
-
related overheads on
calls to other ports


Invocation cost (small for direct connection)


Language interoperability costs (“translate” some data types)


Design application architecture to minimize overheads


Methods in ports should do enough work to amortize overheads


Language costs can be minimized for most scientific computing


No CCA overhead on
parallel interactions


Costs for
distributed computing

depend on network
protocols, etc.


CCA

Common Component Architecture

81

Advanced CCA Concepts


Components are
peers


Application architecture determines relationships, not CCA
specification


Frameworks provide a
BuilderService

which allows
programmatic composition

of components


Frameworks may
present themselves as components

to other frameworks


A “traditional” application can treat a CCA framework
as a
library

CCA

Common Component Architecture

82

What the CCA isn’t…


CCA doesn’t specify who owns “main”


CCA components are peers


Up to application to define component relationships


“Driver component” is a common design pattern


CCA doesn’t specify a parallel programming environment


Choose your favorite


Mix multiple tools in a single application


CCA doesn’t specify I/O


But it gives you the infrastructure to create I/O components


Use of stdio may be problematic in mixed language env.


CCA doesn’t specify interfaces


But it gives you the infrastructure to define and enforce them


CCA Forum supports & promotes “standard” interface efforts


CCA doesn’t require (but does support) separation of
algorithms/physics from data

CCA

Common Component Architecture

83

What the CCA
is…


CCA is a
specification

for a component environment


Fundamentally, a design pattern


Multiple “reference” implementations exist


Being used by applications


CCA increases productivity


Supports and promotes software interopability and reuse


Provides “plug
-
and
-
play” paradigm for scientific software


CCA offers the flexibility to architect your application as
you think best


Doesn’t dictate component relationships, programming models, etc.


Minimal performance overhead


Minimal cost for incorporation of existing software


CCA provides an environment in which domain
-
specific
application frameworks can be built


While retaining opportunities for software reuse at multiple levels

CCA

Common Component Architecture

84

Concept Review


Ports


Interfaces

between components


Uses/provides

model


Framework


Allows
assembly

of components into applications


Direct Connection


Maintain
performance

of local inter
-
component calls


Parallelism


Framework
stays out of the way

of parallel components


MxN Parallel Data Redistribution


Model coupling
, visualization, etc.


Language Interoperability


Babel
, Scientific Interface Definition Language (
SIDL
)

CCA

Common Component Architecture

CCA Forum Tutorial Working Group

http://www.cca
-
forum.org/tutorials/

tutorial
-
wg@cca
-
forum.org

85

Language Interoperable

CCA Components via



CCA

Common Component Architecture

86

Goal of This Module


Legacy codes


䉡扥汩l敤e䍃䄠䍯浰潮敮瑳



Introduction To:


Babel


SIDL


See Babel in use


“Hello World” example


Legacy Code (Babel
-
wrapped MPI)


CCA Tutorial Example (Numerical Integration)


Relationship between Babel & CCA

CCA

Common Component Architecture

87

What I mean by

“Language Interoperability”

Simulation Framework

(C)

Solver Library

(C++)

Numerical Routines

(f77)

Scripting Driver

(Python)

Visualization System

(Java)

Callback Handlers

(Python)

Callback Handlers

(Python)

CCA

Common Component Architecture

88

One reason why mixing

languages is hard

Native


cfortran.h


SWIG


JNI


Siloon


Chasm


Platform

Dependent

C

C++

f77

f90

Python

Java

CCA

Common Component Architecture

89

Babel makes all supported

languages peers

C

C++

f77

f90

Python

Java

Once a library has been

“Babelized” it is equally

accessable from all

supported languages

This is not a

Lowest Common

Denominator

Solution!

CCA

Common Component Architecture

90

Babel Module’s Outline


Introduction


Babel Basics


How to use Babel in a “Hello World” Example


SIDL Grammar


Example: Babel & Legacy Code


Babel & CCA


Relationship between them


How to write a Babelized CCA Component

CCA

Common Component Architecture

91

Babel’s Two Parts:

Code Generator + Runtime Library

SIDL
interface

description


Babel

Compiler


C++

F77

F90

Python

C

XML

Matlab?

Java


Babel

Runtime


Application

CCA

Common Component Architecture

92

greetings.sidl: A Sample SIDL File

package

greetings
version
1.0 {


interface

Hello {


void setName(
in

string name );


string sayIt ( );


}


class

English
implements
-
all

Hello { }

}

CCA

Common Component Architecture

93

Library Developer Does This...

1.
`babel
--
server=C++ greetings.sidl`

2.
Add implementation details

3.
Compile & Link into Library/DLL

SIDL
interface

description


Babel

Compiler


C++ Skels

C++ Impls

IORs

C++ Stubs

libgreetings.so

CCA

Common Component Architecture

94

Adding the Implementation

string

greetings::English_impl::sayIt()

throw ()

{


// DO
-
NOT
-
DELETE splicer.begin(greetings.English.sayIt)


string msg(“Hello “);


return msg + d_name + “!”;


// DO
-
NOT
-
DELETE splicer.end(greetings.English.sayIt)

}

namespace greetings {

class English_impl {


private:


// DO
-
NOT
-
DELETE splicer.begin(greetings.English._impl)


string d_name;


// DO
-
NOT
-
DELETE splicer.end(greetings.English._impl)

CCA

Common Component Architecture

95

Library User Does This...

1.
`babel
--
client=F90 greetings.sidl`

2.
Compile & Link generated Code & Runtime

3.
Place DLL in suitable location

SIDL
interface

description


Babel

Compiler


IOR Headers

F90 Stubs

libgreetings.so


Babel

Runtime


Application

CCA

Common Component Architecture

96

F90/Babel “Hello World” Application

program

helloclient


use

greetings_English


implicit

none


type
(greetings_English_t) ::
obj


character

(len=80) ::
msg


character

(len=20) ::
name



name=
’World’


call

new
( obj )


call

setName
( obj, name )


call

sayIt
( obj, msg )


call

deleteRef
( obj )


print

*, msg


end

program

helloclient

These subroutines

come from directly

from the SIDL

Some other subroutines

are “built in” to every

SIDL class/interface

CCA

Common Component Architecture

97

SIDL Grammar (1/3):

Packages and Versions


Packages can be nested



Versioned Packages


defined as packages with explicit version number
OR packages enclosed by a versioned package


Reentrant by default, but can be declared final


May contain interfaces, classes, or enums


Unversioned Packages


Can only enclose more packages, not types


Must be re
-
entrant. Cannot be declared final

package foo version 0.1 { package bar { ... } }

CCA

Common Component Architecture

98

SIDL Grammar (2/3):

Classes & Interfaces


SIDL has 3 user
-
defined objects


Interfaces



APIs only, no implementation


Abstract Classes



1 or more methods unimplemented


Concrete Classes



All methods are implemented


Inheritance (like Java/Objective C)


Interfaces may
extend

Interfaces


Classes
extend

no more than one Class


Classes can
implement

multiple Interfaces


Only concrete classes can be instantiated

CCA

Common Component Architecture

99

SIDL Grammar (3/3):

Methods and Arguments


Methods are
public virtual

by default


static

methods are not associated with an object
instance


final

methods can not be overridden


Arguments have 3 parts


Mode: can be
in
,
out
, or
inout

(like CORBA, but
semantically different than F90)


Type: one of (bool, char, int, long, float, double,
fcomplex, dcomplex, array<
Type
,
Dimension
>, enum,
interface, class )


Name

CCA

Common Component Architecture

100

Babelizing Legacy Code

1.
Write your SIDL interface

2.
Generate server side in your native langauge

3.
Edit Implementation (Impls) to dispatch to your code

(Do NOT modify the legacy library itself!)

4.
Compile & Link into Library/DLL


mycode.sidl



Babel

Compiler


Skels

Impls

IORs

Stubs

libmycode.so

legacy_library.so

CCA

Common Component Architecture

101

Known Projects Using Babel

(see
www.llnl.gov/CASC/components/gallery.html

for more)



I implemented a Babel
-
based interface
for the hypre library of linear equation
solvers. The Babel interface was
straightforward to write and gave us
interfaces to several languages for less
effort than it would take to interface to a
single language.

--
Jeff Painter, LLNL.

research.cs.vt.edu/lacsa

CCA

Common Component Architecture

102

Babel & Legacy Code (e.g. MPI)


package mpi version 2.0 {


class Comm {


int send[Int]( in array<int,1,row
-
major> data,


in int dest, in int tag );


...


}

}

mpi.sidl

CCA

Common Component Architecture

103

Babel & Legacy Code (e.g. MPI)


struct mpi_Comm__data {


/* DO
-
NOT
-
DELETE splicer.begin(mpi.Comm._data) */


MPI_Comm com;


/* DO
-
NOT
-
DELETE splicer.end(mpi.Comm._data) */

};

mpi_comm_Impl.h

int32_t

impl_mpi_Comm_sendInt( mpi_Comm self, SIDL_int__array data,


int32_t dest, int32_t tag ) {


/* DO
-
NOT
-
DELETE splicer.begin(mpi.Comm.sendInt) */


struct mpi_Comm__data *dptr = mpi_Comm__get_data( self );


void * buff = (void*) SIDL_int__array_first(data);


int count = length(data);


return mpi_send( buff, count, MPI_INT, dest, tag, dptr
-
>comm);


/* DO
-
NOT
-
DELETE splicer.end(mpi.Comm.sendInt) */

}

mpi_comm_Impl.c

CCA

Common Component Architecture

104

Investing in Babelization can
improve

the interface to the code.

“When Babelizing LEOS [an equation of
state library at LLNL], I completely ignored
the legacy interface and wrote the SIDL the
way I thought the interface should be. After
running Babel to generate the code, I found
all the hooks I needed to connect LEOS
without changing any of it. Now I’ve got a
clean, new, object
-
oriented python interface
to legacy code. Babel is doing much more
than just wrapping here.”

--

Charlie Crabb, LLNL

(conversation)

CCA

Common Component Architecture

105

Babel Module’s Outline


Introduction


Babel Basics


How to use Babel in a “Hello World” Example


SIDL Grammar


Example: Babel & Legacy Code


Babel & CCA


Relationship between them


How to write a Babelized CCA Component

CCA

Common Component Architecture

106

SCIRun2

History of Babel & CCA

XCAT (Indiana)

SciRUN (Utah)

Ccaffeine (SNL)

Babel (LLNL)

Applications

Decaf


Babelized

Frameworks

t

Ccaffeine


CCA

Common Component Architecture

107

The CCA Spec is a SIDL File

package
gov {

package

cca
version

0.6.2 {


interface

Port { }


interface

Component {


void setServices( in Services svcs );


}


interface

Services {


Port getPort( in string portName );


registerUsesPort(
/*etc*/

);


addProvidesPort(
/*etc*/

);


/*etc*/

CCA

Common Component Architecture

108

The CCA from Babel’s POV

CCA

Common Component Architecture

109

Decaf:

Details & Disclaimers


Babel is a hardened tool


Decaf is an example, not a product


Distributed in “examples” subdirectory of Babel


Decaf has no GUI


Decaf is CCA compliant


Babelized CCA Components can be loaded into
Decaf, CCAFFEINE, and SCIRun2


“Understanding the CCA Specification
Using Decaf”
http://www.llnl.gov/CASC/components/do
cs/decaf.pdf


CCA

Common Component Architecture

110

How I Implemented Decaf

1.
wrote decaf.sidl file

2.
`babel
--
server=C++ cca.sidl decaf.sidl`

3.
Add implementation details

4.
Compile & Link into Library/DLL

cca.sidl

&

decaf.sidl


Babel

Compiler


C++ Skels

C++ Impls

IORs

C++ Stubs

libdecaf.so

CCA

Common Component Architecture

111

How to Write and Use

Babelized CCA Components

1.
Define “Ports” in SIDL

2.
Define “Components” that implement those
Ports, again in SIDL

3.
Use Babel to generate the glue
-
code

4.
Write the guts of your component(s)



CCA

Common Component Architecture

112

How to Write A

Babelized CCA Component (1/3)

1.
Define “Ports” in SIDL


CCA Port =


a SIDL Interface


extends gov.cca.Port

package
functions
version

1.0 {



interface

Function
extends

gov.cca.Port {


double evaluate( in double x );


}

}

CCA

Common Component Architecture

113

How to Write A

Babelized CCA Component (2/3)

2.
Define “Components” that implement those Ports


CCA Component =


SIDL Class


implements gov.cca.Component (& any provided ports)

class

LinearFunction
implements
functions.Function,


gov.cca.Component {


double evaluate( in double x );


void setServices( in cca.Services svcs );

}

class

LinearFunction
implements
-
all



functions.Function, gov.cca.Component { }

CCA

Common Component Architecture

114

Tip: Use Babel’s XML output like
precompiled headers in C++

1.
precompile SIDL into XML


--
text=xml

2.
store XML in a directory

3.
Use Babel’s

R option to
specify search directories


cca.sidl



Babel

Compiler


XML

Type

Repository


functions.sidl



Babel

Compiler


Skels

Impls

IORs

Stubs

CCA

Common Component Architecture

115

How to Write A

Babelized CCA Component (3/3)

3.
Use Babel to generate the glue code


`babel
--
server=C

Rrepo function.sidl`

4.
Add implementation details

SIDL
interface

description


Babel

Compiler


C Skels

C Impls

IORs

C Stubs

libfunction.so

Repo

(XML)

CCA

Common Component Architecture

116

To Use the Decaf Framework

1.
`babel
--
client=Java

Rrepo function.sidl`

2.
Compile & Link generated Code & Runtime

3.
Place DLLs in suitable location


SIDL files



Babel

Compiler


IOR Headers

Java Stubs


Babel

Runtime


Application

Repo

(XML)

component1.so

libdecaf.so

CCA

Common Component Architecture

117

Limitations of Babel’s Approach

to Language Interoperabilty


Babel is a code generator


Do obscure tricks no one would do by hand


Don’t go beyond published language standards


Customized compilers / linkers / loaders beyond our
scope


E.g. icc and gcc currently don’t mix on Linux


E.g. No C++
-
style templates in SIDL. (Would require special
linkers/loaders to generate code for template instantiation,
like C++ does.)


Babel makes language interoperability feasible, but
not trivial


Build tools severely underpowered for portable multi
-
language codes

CCA

Common Component Architecture

118

What’s the Hardest Part

of this Process?


Properly building libraries for multi
-
language use


Dynamically loadable .so files are especially error prone


Not a lot of understanding or expertise in community


Causality chain between improperly constructed DLLs and
observed bugs is often inscrutable and misleading

SIDL
interface

description


Babel

Compiler


C Skels

C Impls

IORs

C Stubs

libfunction.so

CCA

Common Component Architecture

119

Summary

Legacy codes


䉡扥汩穥搠䍃䄠䍯浰潮C湴n



Reclassify your objects in your legacy code


Things customers create


CCA components


Logical groups of a component’s functionality


CCA Port


Low level objects in your implementation


not exposed


Generate SIDL File


CCA port


Babel Interface that extends the Babel interface
called “gov.cca.Port”


CCA component


Babel Class that implements the Babel
interface called “gov.cca.Component” (and possibly its
“provides ports”)


Run Babel (choose server
-
language for your code)


Articulate Impl files to dispatch to legacy code

CCA

Common Component Architecture

120

Contact Info


Project:
http://www.llnl.gov/CASC/components


Babel: language interoperability tool


Alexandria: component repository


Quorum: web
-
based parliamentary system


Gauntlet (coming soon): testing framework


Bug Tracking:


http://www
-
casc.llnl.gov/bugs


Project Team Email:


components@llnl.gov


Mailing Lists:



majordomo@lists.llnl.gov

subscribe babel
-
users
[email address]

subscribe babel
-
announce
[email address]

CCA

Common Component Architecture

CCA Forum Tutorial Working Group

http://www.cca
-
forum.org/tutorials/

tutorial
-
wg@cca
-
forum.org

121

A Look at More Complex
Component
-
Based Applications


CCA

Common Component Architecture

122

Modern Scientific Software Development


Terascale computing will enable high
-
fidelity calculations based on
multiple coupled physical processes and multiple physical scales


Adaptive algorithms and high
-
order discretization strategies


Composite or hybrid solution strategies


Sophisticated numerical tools

Discretization

Algebraic Solvers

Data Redistribution

Mesh

Data Reduction

Physics Modules

Optimization

Derivative Computation

Collaboration

Diagnostics

Steering

Visualization

Adaptive Solution

Time Evolution

CCA

Common Component Architecture

123

Overview


Using components in high performance simulation
codes


Examples of increasing complexity


Performance


Single processor


Scalability


Developing components for high performance
simulation codes


Strategies for thinking about your own application


Developing interoperable and interchangeable components

CCA

Common Component Architecture

124

Our Starting Point


2


(x,y) = 0


[0,1] x [0,1]


(0,y)=0

(1,y)=sin (2

y)


/

y(x,0) =

/

y(x,1) = 0

Discretization

Algebraic Solvers

Mesh

Physics Modules

Visualization

CCA

Common Component Architecture

125

Numerical Solution of Example 1


Physics: Poisson’s equation


Grid: Unstructured triangular mesh


Discretization: Finite element method


Algebraic Solvers: PETSc (Portable
Extensible Toolkit for Scientific Computation)


Visualization: VTK tool


Original Language: C

CCA

Common Component Architecture

126

Creating Components: Step 1


Separate the application code into well
-
defined
pieces that encapsulate functionalities


Decouple code along numerical functionality


Mesh, discretization, solver, visualization


Physics is kept separate


Determine what questions each component can ask of and
answer for other components (this determines the ports)


Mesh provides geometry and topology (needed by
discretization and visualization)


Mesh allows user defined data to be attached to its entities
(needed by physics and discretization)


Mesh
does not

provide access to its data structures


If this is not part of the original code design, this is by far the
hardest, most time
-
consuming aspect of componentization

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Creating the Components: Step 2


Writing C++ Components


Create an abstract base class for each port


Create C++ objects that inherit from the abstract base port
class and the CCA component class


Wrap the existing code as a C++ object


Implement the setServices method


This process was significantly less time consuming
(with an expert present) than the decoupling process


Lessons learned


Definitely look at an existing, working example for the targeted
framework


Experts are very handy people to have around ;
-
)

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The Componentized Example


The Driver Component


Responsible for the overall
application flow


Initializes the mesh, discretization,
solver and visualization
components


Sets the physics parameters and
boundary condition information

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The Componentized Example


The Driver Component


Responsible for the overall
application flow


Initializes the mesh, discretization,
solver and visualization
components


Sets the physics parameters and
boundary condition information


The Mesh Component


Provides geometry, topology, and
boundary information


Provides the ability to attach user
defined data as tags to mesh
entities


Is used by the driver,
discretization and visualization
components

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The Componentized Example


The Driver Component


Responsible for the overall
application flow


Initializes the mesh, discretization,
solver and visualization
components


Sets the physics parameters and
boundary condition information


The Mesh Component


Provides geometry and topology
information


Provides the ability to attach user
defined data to mesh entities


Is used by the driver,
discretization and visualization
components


The Discretization Component


Provides a finite element
discretization of basic operators
(gradient, Laplacian, scalar terms)


Driver determines which terms are
included and their coefficients


Provides mechanisms for general
Dirichlet and Neumann boundary
condition matrix manipulations


Computes element matrices and
assembles them into the global
stiffness matrix via set methods
on the solver


Gathers and scatters vectors to
the mesh (in this case

)

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The Componentized Example


The Driver Component


Responsible for the overall
application flow


Initializes the mesh, discretization,
solver and visualization
components


Sets the physics parameters and
boundary condition information


The Mesh Component


Provides geometry and topology
information


Provides the ability to attach user
defined data to mesh entities


Is used by the driver,
discretization and visualization
components


The Discretization Component


Provides a finite element
discretization of basic operators
(gradient, laplacian, scalar terms)


Provides mechanisms for general
Dirichlet and Neumann boundary
condition manipulations


Computes element matrices and
assembles them into the global
stiffness matrix via set methods
on the solver


Gathers and scatters vectors to
the mesh (in this case

)


The Solver Component


Provides access to vector and
matrix operations (e.g., create,
destroy, get, set)


Provides a “solve” functionality for
a linear operator

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The Componentized Example


The Driver Component


Responsible for the overall
application flow


Initializes the mesh, discretization,
solver and visualization
components


Sets the physics parameters and
boundary condition information


The Mesh Component


Provides geometry and topology
information


Provides the ability to attach user
defined data to mesh entities


Is used by the driver,
discretization and visualization
components


The Discretization Component


Provides a finite element
discretization of basic operators
(gradient, laplacian, scalar terms)


Provides mechanisms for general
Dirichlet and Neumann boundary
condition manipulations


Computes element matrices and
assembles them into the global
stiffness matrix via set methods
on the solver


Gathers and scatters vectors to
the mesh (in this case

)


The Solver Component


Provides access to vector and
matrix operations (e.g., create,
destroy, get, set)


Provides a “solve” functionality for
a linear operator


The Visualization Component


Uses the mesh component to print
a vtk file of


on the unstructured
triangular mesh


Assumes user data is attached to
mesh vertex entities

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The next step… time dependence


/

t =

2


(x,y,t)


[0,1] x [0,1]


(0,y,t)=0

(1,y,t)=.5sin(2

y)cos(t/2)


/

y(x,0) =

/

y(x,1) = 0


(x,y,0)=sin(.5

x) sin (2

y)

Time Evolution

Discretization

Algebraic Solvers

Mesh

Physics Modules

Visualization

Data Redistribution

Distributed Arrays

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Some things change…


Requires a time integration component


Based on the LSODE library (LLNL)


Component implementation developed by Ben Allan (SNL)


Uses a new visualization component


Based on AVS


Requires an MxN data redistribution component


Developed by Jim Kohl (ORNL)


The MxN redistribution component requires a Distributed Array
Descriptor component


Similar to HPF arrays


Developed by David Bernholdt (ORNL)


The driver component changes to accommodate the new
physics

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… and some things stay the same


The mesh component doesn’t change


The discretization component doesn’t change


The solver component doesn’t change


What we use from the solver component changes


Only vectors are needed


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The CCA wiring diagram


Reused


Integration


Visualization


Driver/Physics

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What did this exercise teach us?


It was easy to incorporate the functionalities of
components developed at other labs and institutions
given a well
-
defined interface and header file.


In fact, some components (one uses and one provides) were
developed simultaneously across the country from each
other after the definition of a header file.


Amazingly enough, they usually “just worked” when linked
together (and debugged individually).


In this case, the complexity of the component
-
based
approach was higher than the original code
complexity.


Partially due to the simplicity of this example


Partially due to the limitations of the some of the current
implementations of components


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Beyond the heat equation…


Flame Approximation


H
2
-
Air mixture; ignition via 3 hot
-
spots


9
-
species, 19 reactions, stiff chemistry


Governing equation





Domain


1cm X 1cm domain


100x100 coarse mesh


finest mesh = 12.5 micron.


Timescales


O(10ns) to O(10 microseconds)


i
i
i
w
Y
t
Y








.
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Numerical Solution


Adaptive Mesh Refinement: GrACE


Stiff integrator: CVODE (LLNL)


Diffusive integrator: 2
nd

Order Runge Kutta


Chemical Rates: legacy f77 code (SNL)


Diffusion Coefficients: legacy f77 code (SNL)


New code less than 10%

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The CCA Wiring Diagram


Reused


Slow Time Scale Integration


Fast Time Scale Integration


Driver/Physics

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141

Evolution of the Solution

Temperature

OH Profile

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142

The need for AMR


H
2
O
2

chemical subspecies profile


Only 100 microns thick (about 10 fine level cells)


Not resolvable on coarsest mesh

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Common Component Architecture

143

Computational Chemistry:

Molecular Optimization


Problem Domain:

Optimization of
molecular structures using quantum
chemical methods


Investigators:

Yuri Alexeev (PNNL), Steve Benson (ANL),
Curtis Janssen (SNL), Joe Kenny (SNL), Manoj Krishnan
(PNNL), Lois McInnes (ANL), Jarek Nieplocha (PNNL),
Jason Sarich (ANL), Theresa Windus (PNNL)


Goals:

Demonstrate interoperability among software
packages, develop experience with large existing code
bases, seed interest in chemistry domain

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Molecular Optimization Overview


Decouple geometry optimization from electronic structure


Demonstrate interoperability of electronic structure components


Build towards more challenging optimization problems, e