Scalable Science on the Web?Challenges and Possibilities

Don Brutzman

Modeling, Virtual Environments and Simulation (MOVES)Naval Postgraduate School, Monterey California

brutzman@nps.navy.mil

NSF Workshop: Grand Challenges eScience

5 December 2001 THE MOVES INSTITUTE

Two topics (rants)

Scientific method, modeling & simulationProposed “grand challenge” for Science on Web

Enabling technologies

3D, XML languages, behaviors, networking, physics

aka large-scale virtual environments

5 December 2001 THE MOVES INSTITUTE

Some definitions

ModelRepresentation of process in real world

SimulationBehavior of a model over time

5 December 2001 THE MOVES INSTITUTE

Scientific method

For many hundreds of years, scientific method has essentially been repetition of two steps:

Theory Experiment

However, two virtual analogs now exist:

Modeling Simulation

5 December 2001 THE MOVES INSTITUTE

Typical process: hypothesize, test, repeat

Theory Experiment

Modeling Simulation

Process of scientific inquiry

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Actual practice more often a combination of each:

Theory Experiment

Modeling Simulation

Process of scientific inquiry

5 December 2001 THE MOVES INSTITUTE

Simulation advantages over experimentation

Repeatable, adjustable, low cost or “free”

Can insert various error distributions Zero-error perfect case for algorithm correctness Statistically definable for measuring variations, rigor Can be intentionally extreme to test robustness

Can predict otherwise-impossible conditions

Catastrophic failure (of simulated system) is OK

5 December 2001 THE MOVES INSTITUTE

Simulation complementing experimentation

Forward: can sometimes insert experimental data into simulations

Mix of both needed for Verification (computationally stable)Validation (predictions match measured results)

Reverse: can sometimes insert simulation data into experiments

5 December 2001 THE MOVES INSTITUTE

Most Ignored Word in Computer Science

“Science”

How many computer scientists run experiments?Fairly widespread problem / occupational hazardTry looking for Experimental Results section in

conference, journal papersMost other disciplines won’t publish without resultsHmm, what about Simulation Results sections?

and the answer is…

5 December 2001 THE MOVES INSTITUTE

Science characteristics

Theories and models tend to be disjointor at least disconnected

Assumptions, limitations and inputs of one model tend to be outputs of another modelConjectural, but experts tend to know how

contributions in their field all fit together

Biggest challenges are often cross-disciplinary

5 December 2001 THE MOVES INSTITUTE

Science characteristics

Good experimental data is usually available for theoretical modelsAt least within limited ranges of experimentsNot usually available, though (despite NSF efforts)

Simulation results crucial to conducting sciencebut simulations are rarely reported, published, linked

or re-used Interchangeability of simulations and experiments is

not supported

5 December 2001 THE MOVES INSTITUTE

proposed Grand Challenge in e-Science

Enable scalable interconnection of Science on the Web, using

theoretical models, experimental results and simulation results.

5 December 2001 THE MOVES INSTITUTE

Enabling technologies

XML schemas for Scientific languages: MathML, Chemistry ML, etc. Others possible, even experiment-specific schema Integration feasible through XML namespaces

Metadata Dublin Core, Resource Description Framework (RDF) Semantic Web enables agents and other processes

Internationalization (i18n) and Localization We also live on planet Earth, not just in U.S.A.

5 December 2001 THE MOVES INSTITUTE

Enabling technologies

X3D graphics: Web interchange for 3D modelsmodel composition occurs in virtual environments Web-adept integration with other XML languages

Behavior protocolsSo scenes, models, humans etc. (i.e. applications)

can interact

Networking infrastructureClient, server, peer-to-peer, monitoring, services

5 December 2001 THE MOVES INSTITUTE

Extensible 3D (X3D)

X3D graphics: Web interchange for 3D modelsVirtual Reality Modeling Language (VRML) 3rd generation ISO standard with XML encoding3D render hardware already deployed everywhereGet 3D models “out of box,” out of proprietary islandshttp://www.web3D.org

Deliverables:Specification Tagset

API Authoring tools

Content Conformance

5 December 2001 THE MOVES INSTITUTE

Configuring Powerpoint for 3D

Takes a few minutes of configuration to set up:

http://web.nps.navy.mil/~brutzman/Savage/ InstallingCortonaBrowserAsPowerpointControl.ppt

http://web.nps.navy.mil/~brutzman/Savage/ InstallingCortonaBrowserAsPowerpointControl.html

5 December 2001 THE MOVES INSTITUTE

online X3D/VRML example: gimbals[go to full-screen Presentation mode to activate]

[PgUp/PgDn to change viewpoints, arrow keys or mouse to rotate][PgUp/PgDn to change viewpoints, arrow keys or mouse to rotate]

5 December 2001 THE MOVES INSTITUTE

online X3D/VRML example: kelp forest[go to full-screen Presentation mode to activate]

[PgUp/PgDn to change viewpoints, arrow keys or mouse to rotate][PgUp/PgDn to change viewpoints, arrow keys or mouse to rotate]

5 December 2001 THE MOVES INSTITUTE

3D myths, enablers

File size is bigActually much smaller than video/audio, with added

benefits of interactivity and viewpoint independence

Modeling is hardData-driven autogeneration using templates works “Content is king”

Navigation interfaces are klunkyYes, sorta like hypermedia prior to NCSA Mosaic

5 December 2001 THE MOVES INSTITUTE

A simple challenge?

Goal: Clearly demonstrate XML language interoperability

Example: Collaborative visualization for cardiac diagnosis

XHTML: hypermedia web pagesSVG: Scalable Vector Graphics 2D diagramsSMIL: Synchronized Multimedia Interface Language streamsMathML: biomechanical, biochemical modelsX3D: visualize changes to 3D model of heart

5 December 2001 THE MOVES INSTITUTE

Behavior protocols

Highly specialized application-level protocols

Perhaps unique to each type of model

Examples: IEEE Distributed Interactive Simulation (DIS) protocolW3C XML Protocol (XP) work, SOAP, othersNPS Dynamic Behavior Protocol

XML-defined packet payload, can modify/replace at run time

5 December 2001 THE MOVES INSTITUTE

Network considerations, needs

Client operations: applications, obviously

Server operations: needed but typically blocked

Multicast: multiple interactions simultaneously Scalable peer-to-peer communications Area of interest management (AOIM) Robust fallback to unicast tunneling

Network monitoring Controlled, repeatable experimental environment Repeatability more important than strict causality Much bigger than 2-point optimization

5 December 2001 THE MOVES INSTITUTE

Network considerations, needs

Support services NTP for clock synchronization LDAP for directory/discovery services, e.g. VRDNS Security for signing, authenticity, etc. Repositories and archives of interoperable content

Common theme: “middleware solutions” needed but framework is the enabler, not a legislative end goal

Forcing function/goal: growth, composability and scalability matching the capabilities and growth patterns of Web

Push all the way to desktops, not just infrastructure

5 December 2001 THE MOVES INSTITUTE

Some physics considerations

Physics of interactions between models needed Important part of VR is reality, not virtual

Some intractable problems are yieldinge.g. N-N collision detection appears tractable using

variable-resolution algorithms + network partitioningShared supercomputer problems, solutions

Typically low-resolution physics on clients, then high-res physics on servers as shared resourceGood application area for reliable multicast

5 December 2001 THE MOVES INSTITUTE

Some physics considerations

Contrast in disciplines Operations Research (OR) has rigorously consistent

mathematical notation, definitions Mechanical Engineering (ME) hydrodynamics doesn’t

Progress is much harder to validate, repeat Probably typical situations for other sciences too

Backdrop of “real world” data has caught up Terrain, satellite imagery, remote sensing, etc. etc. Needs to be available on demand as initial conditions,

bounding assumptions, model/simulation/experimental data in its own right

5 December 2001 THE MOVES INSTITUTE

proposed Grand Challenge in e-Science (reprised)

Enable scalable interconnection of Science on the Web, using

theoretical models, experimental results and simulation results.

Web 3D virtual environments are where these capabilities will be most needed and most visible.

5 December 2001 THE MOVES INSTITUTE

Contact

Don Brutzman

brutzman@nps.navy.mil

http://web.nps.navy.mil/~brutzman

Code UW/Br, Naval Postgraduate School

Monterey California 93943-5000 USA

831.656.2149 voice

831.656.3679 fax