GridSphere/Portlet Workshop, March 3 rd – 4 th, 2005 LC Portal via GridSphere Mark Baker and Hong...

GridSphere/Portlet Workshop, March 3rd – 4th, 2005

LC Portal via GridSphere

Mark Baker and Hong OngDistributed Systems GroupUniversity of Portsmouth


Contents

• Overview of the Liquid Crystal (LC) application.

• Introduction to the LC Portal:– The early Perl based generation,– The next JSR 168 based generation.

• Comments on our experiences.


Liquid Crystal Application

• Modeling liquid crystalline materials.• Determine minimum energy configuration

of liquid crystals in a slab.• Landau-de Gennes formulation in terms of

tensor order parameter Q, and temperature T.

• Free energy is represented as:F(Q, T) = Fvol (Q, T) + Fsurf(Q)

= fvol (Q, T) dV + fsurf(Q) dS,

where =(x1, x2, x3x1 a, 0 x2 b, 0 x3

c }.


Solving Free Energy Equation

• Solve the Euler-Lagrange equations.

• Consider 100 points per edge:– Give a linear system

with 5x106 unknowns.– Use MINRES, Krylov

subspace method.

• Written in C/Fortran. • In-house MPI “BLAS”

code.• Visualization.


LC Portal: Architecture

• The architecture is based on the “three-tier” model.

Presentation

Web Logic

Backend


LC Portal: Internal Architecture

Servlet Host

Portal Host

Tomcat J SP Engine

Apache Webserver

State Storage (SQL) File)

J SP I ntrsp.

CoG

Web

Browser

Client Portlet

HTTPS (port 443)

MI ME Launcher Launched

Grid Resources

AJ P (port XXXX)

Firewall

Direct socket connection

to Grid Service


LC Portal: Workflow

LC Web Portal

Visualization

Submission and Control

LC Render Cluster

MPI version of POVRay

Job Submit and

Control

LC Compute Cluster

MPI version ofLC Code

GSI-FTP

GSI-FTP

1

2

3


LC Portal: The 2002 Version


LC Portal: Interface

Allow users to configure the liquid crystals representation.

Allow users to modify the simulation parameters

Allow user to change the viewing aspects

Control buttons for submitting jobs.


Web Portal/Portlet Technologies

• Many Web portals implementations:– Create compatibility problems for Application Providers,

Portal Consumers, and Portal Server.

• Web application development is a tedious task:– Lack of reusable components, – Developers constantly have to “re-invent” the wheel.

• Portal/Portlet standards include:– JSR-168: Similar to Servlet API for providing reusable web

applications. – JSR-127: Specifies an event-based user interface for web

presentation development.– Web Services for Remote Portlets (WSRP): Specifies how

web services can be consumed by standards compliant portals.

Some Portal/Portlet Implementations

• Current vendors: – IBM WebSphere,– Oracle Portal,– Sun Application Server.

• Open source projects:– Jakarta Pluto (Jetspeed), Jetspeed 2, and wsrp4j,– Exo, Liferay, and Cocoon 2.

• Academic projects:– GridSphere, Sakai, and uPortal.


LC Portal: The 2004 version


LC Portal: Interface

Resources Browser

MyProxy Portlet

LC Portlet


Comments on Some Experiences

• Recall, we wanted:– Client-> HTTP server -> Tomcat (either local or remote),– Clients should see only https://<server>/<context-path>,– Clients should access remote resource via Grid Portlets.

• At AHM, Hong talked to people who are using GS:– Found out none has investigated this route,– Changing the context.xml is not enough because GS

assumes webapps are deploy to http://<server>:<port>/,

• Modified GS source code:– Fully integrated with Apache2 and Tomcat4 using mod_jk

module.

• So, does it work?


The Good!

• Web Portal - one ring to rule them all.– A single interface to control distributed resources,– Workflow that cross multiple machines or organizations.

• Hiding complexity of the Web/Grid:– Manage complexity on one machine instead of many,– Uniform user environment.

• Delegating tasks:– Users hate to install/configure anything! – Web/Grid client software management remains

challenging,– Developers handle the nitty gritty deployment details.


The Bad!


The Ugly!



• Grid portlets from GS do not work (for us):– In the end, we used Grid portlets from OGCE, which

include GridPort portlet.

• Configuration requires a lot of effort.• Legacy application might not be able to represent

as portlets. – So, do we have to start from scratch?

• Portlet development issues:– What is the trade off between a portlet orchestrating a lot

of web services as compared to simply using WSRP?– Is it a good idea to write code in WSRP, JSR-168, JSR-127,

or combination?– In the real world, a portal will be built from components

from many sources, so are we back to square one again?



• Firewall Issues:– Ports need to be opened for some services to

communicate with each other,– Ports management remains challenging.

• Integration Issues:– If the WSRP to JSR-168 API works out well, each

portal should both be a WSRP producer and consumer,

– This implies significant opportunity for creating federated portals,

– However, there is much work to do in this area to fully realize this potential at the moment.


Concluding Remarks

• Portlet standards provide a uniform way to develop a user Web portal.

• More portlets (Grid/Web) need to be made available.

• Applications presented as WS/Portlet has many benefits.

• Installation and deployment still remain challenging.

• Integration of portals/portlets still remain problematic.

• Most portlet frameworks are still research projects and may not be ready for prime time.


Questions?

GridSphere/Portlet Workshop, March 3 rd – 4 th, 2005 LC Portal via GridSphere Mark Baker and Hong...

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