Transcript Grid Portals – A Gateway to Grid Applications

Building Web Portals as
Science Gateways
Marlon Pierce
[email protected]
with slides from Dennis Gannon, Ahmet Sayar, Galip
Aydin
Indiana University
Outline of Talk
• Overview of computing portals as gateways to
cyberinfrastructure.
– With several example projects
• Architectures and standards of computing
portals.
– Review of portal architectures
– Review of JSR168
• Building science portals.
– With a motivating example
• New technologies and techniques
– JSF
– AJAX
Computing for the Greater Good
• Recent devastating natural disasters have
demonstrated the need for large scale,
distributed scientific computing.
– Katrina, Rita, …
– Christmas 2004 tsunamis
– Earthquakes in Pakistan and future major
earthquakes in California, Japan, …
• 1906 was 99 years ago…
• Research in large scale distributed computing
can make a difference in people’s lives.
• But many challenges lie ahead.
Cyberinfrastructure (CI) Overview
• Cyberinfrasture combines
– Grid computing:
• Globus toolkit, Storage Resource Broker, Condor, UK OMII, OGSADAI, etc.
• Provides the software for tying together distributed computing
resources
– High speed networking
– Hardware: supercomputers, clusters, workstations
– Applications: modeling, simulation, data analysis codes in many
fields.
– Data: raw, cooked, shared, derived, cataloged, etc.
– Information/Internet Technology: web services, portals,
databases, XML, semantic web/grid, audio/video collaboration,
shared Web spaces, etc.
– People
• Cyberinfrastructure is supposed to enable remote collaborations
and distributed teams.
• This is the reality of a lot of science (and science funding)
Scientific Challenges
Genetics and Disease Susceptibility
Science Communities and Outreach
• The current and future
generations of scientific
• Communities
problems
are:
• CERN’s Large Hadron Collider
– Data
Oriented (CI challenge)
experiments
•
•
•
Increasingly
stream
based.
• Physicists working
in HEP
and
Often
need
archives
similarly
datapetabyte
intensive scientific
But
linking data to applications
disciplines
across
groups
is a general
• National
collaborators
and those
problem.
across the digital divide in
disadvantaged
countries
– In need
of on-demand
computing
resources (CI
• Scope
challenge)
• Interoperation between LHC
Data Grid Hierarchy
and ETF
– Conducted
by
• Create and Deploydistributed
Scientific
geographically
Dataof
andspecialists
Services Grid Portals
teams
• Bringdon’t
the Power
to bear
• Who
wantoftoETF
become
on LHCin
Physics
Analysis: Help
experts
grid computing.
discover the Higgs Boson!
Phenotype 1
Phenotype 2
Phenotype 3 Phenotype 4
Ethnicity
Environment
Age
Gender
• Partners
Identify Genes
• Caltech
Pharmacokinetic s
• UniversityMetabolism
ofFlorida Endocrine
Biomarker
Physiology
Proteome
• Open Science
Grid
and Grid3
Signatures
Transcriptome
Immune
Morphometrics
• Fermilab
• DOE PPDG
Predictive Disease Susceptibility
Terry Magnuson, UNC
•Source:
CERN
Storms Forming
• NSF GriPhyn and iVDGL
Forecast Model
Streaming• EU LCG and EGEE
Data Mining
Observations
• Brazil (UERJ, …)
On-Demand
• Pakistan (NUST, …)
Storm predictions
• Korea (KAIST,…)
LHC Data Distribution Model
Science Web Portals
The goals of a Science Web Portal are
– To give a community of researchers easy access to
•
•
•
•
Computational applications and tools
Primary data, shared data, derived data
Computational resources
All are needed to solve today’s scientific and engineering
problems.
– To do this in a discipline specific language that is
common to the target community.
• Science Portals are “gateways” to underlying
Grid tools
– Grids provide access to computing resources
– Gateways manage the user’s interaction with the grid.
What is a Science Portal?
• A standards-based web portal
– Provides each user with
• a secure way to login and authenticate identity
• A view of a private workspace for accessing and
managing data and tools
• Tutorials and community news
– Announcements of new services
• Collaboration tools
– Chat, calendaring, group messaging
• Core Science Functions …
Portal Science Capabilities
• Data Access is the most important
– Allow the user community access to important shared
data resources
• Visualize it, publish it, download it, curate it.
– Data Discovery
• Searchable metadata directories.
• Web access to important tools
– Web-form interfaces to allow users to run important
community codes
– Webstart access to common java-based tools
• Workflow tools
– Allow users to combine community codes into
workflows managed by the portal back-end
resources.
Let’s look at a few real
examples
(about a dozen … many more
exist!)
ServoGrid Portal
NEESGrid
Realtime access to earthquake
Shake table experiments at remote sites.
Geological Information Grid Portal
Mesoscale Meteorology
NSF LEAD project - making the tools that
are needed to make accurate predictions of
tornados and hurricanes.
- Data exploration and Grid workflow
Renci Bio Portal
Providing access to biotechnology tools running on a back-end Grid.
- leverage state-wide
investment in
bioinformatics
- undergraduate &
graduate education,
faculty research
- another portal
soon:
national evolutionary
synthesis center
SCOOP ADCIRC Interface
Set Run Dates
Current ADCIRC grid
Decomposition
•
SURA SCOOP
–
•
Southeastern Coastal Ocean Observing Program
Advanced Circulation Model (ADCIRC)
–
Finite Element Hydraulic Model for Coastal Areas, Inlets and Rivers
•
•
•
Rick Luettich (UNC), Joannes Westerink (Notre Dame)
Randall Kolar (Oklahoma), Clint Dawson (Texas), Corps of Engineers
Collaborators:
–
–
Leuttich/Blanton (UNC Marine Sciences)
Ramakrishnan/Lander (RENCI)
Katrina Storm Surge Prediction
(Leuttich/Blanton)
X-Ray Crystallography
Flood Modeling
• University of
Texas
•TACC
•Center for
Research in
Water Resources
• ORNL
• Purdue
Large-scale flooding along Brays Bayou in central Houston triggered by
heavy rainfall during Tropical Storm Allison (June 9, 2001) caused more
than $2 billion of damage.
Gordon Wells, UT; David Maidment, UT; Budhu Bhaduri, ORNL, Gilbert Rochon, Purdue
Teragrid Gateway Portals
• TeraGrid
– The largest “public” supercomputing grid in the US.
• 50 TFlops
– Massive Data storage capability
• Over 1 Petabyte on-line storage
• TeraGrid Gateways
– Access points for communities.
– Two types:
• A gateway between 2 grids
– Open Science Grid gate way is one example.
– Science Community Portal is the other type
• Includes LEAD portal, Nanohub, Renci Bioportal, NVO
• An additional set of new science portals just being
developed.
The Portal as a Service Framework
• Many important science portals are
designed to access and orchestrate standalone web services and databases
• Others are service frameworks that sit on
top of an existing Grid, such as TeraGrid.
• In both cases:
– The architecture is similar
– Common portal services are often shared
• A Common architecture is emerging
The Architecture of Gateway Services
The Users Desktop.
Grid
Portal Server
Gateway Services
Proxy Certificate
Server / vault
Application
Workflow
Application
Deployment
Application Events
Resource Broker
App. Resource
catalogs
User Metadata
Catalog
Replica Mgmt
Core Grid Services
Security
Services
Information
Services
Self
Management
Resource
Management
OGSA-like Layer
Physical Resource Layer
Execution
Management
Data
Services
Next Steps
• Many components of this architecture are
now shared between different portal
groups.
• We now look at some of the technology
behind these portals.
A Portal Architecture
Review
A Famous Web Portal
A Famous Portal, After Login
What to Notice

After logging in, my colors, layouts, and
content all changed.
• I get my stock list, my Bloomington weather, my
news stories, etc.
• I got rid of “Garfield”

As we will see later, each of these content
fragments (encircled) is managed by a thing
called a portlet…
• … I don’t guarantee that this is true for Yahoo’s
web site but it is true for a large class of
enterprise Java portal systems.

Portlets are the key to portal software reuse.
Let 10,000 Flowers Bloom

Many portal projects have been launched
since late ’90s.
• First Generation: HotPage from SDSC, NCSA
efforts, DOD, DOE Portals, NASA IPG
• 2002 Special Issue of Concurrency and
Computation: Practice and Experience.

The field continues to be active
• Global Grid Forum 14 Science Gateway workshop
in June 2005.
• About 15 gateways will be described in upcoming
issue of Concurrency.
• GCE2005 workshop at Supercomputing 05.

How do we share and reuse all of this work?
Three-Tiered Architecture
Portal User Interface
Grid and
Web
Protocols
JDBC,
Local, or
Remote
Connection
Portal
Client
Stub
Database
Service
Database
Portal
Client
Stub
Grid Resource
Broker Service
HPC
or
Compute Cluster
Portal
Client
Stub
Information
and
Data Services
Grid Information
Services, SRB
Three-tiered architecture is accepted standard for
accessing Grid and other services
JSR 168 Overview
Java Portlet Standard
What Is a Portlet?


A portlet is a piece of Java code that manages the
content of one section of a web portal’s HTML.
It can do anything else that a Java web application
can do.
• You can connect a portlet to a database, invoke a web
service, download an RSS feed, etc.


It lives in a portlet container, which creates,
manages, and destroys all the portlets of the portal.
Portlet containers are part of portals.
• Portals must do other things like manage login, users,
groups, layouts, etc.

JSR 168 standardizes two main things:
• How the portlet container manages portlet lifecycles
• How the portlets are programmed.
What is JSR 168?

From the portlet development point of view,
it is really very simple:
• You write a java class that extends
GenericPortlet.
• You override/implement several methods
inherited from GenericPortlet.
• You use some supporting classes/interfaces



Many are analogous to their servlet equivalents
Some (portletsession) actually seem to be trivial
wrappers around servlet equivalents in Pluto.
A complete example is available from
• http://www.servogrid.org/slide/iSERVO/NMI/OG
CETutorialMaterial
Some Open Source JSR 168
Containers

GridSphere
• http://www.gridsphere.org

uPortal
• http://www.uportal.org

LifeRay
• http://sourceforge.net/projects/lportal

eXo platform
• http://www.exoplatform.com

StringBeans
• http://www.nabh.com/projects/sbportal

Jetspeed2
• http://portals.apache.org/jetspeed-2/
Some GenericPortlet.java Methods
Method
Description
Init
Called when the portlet is created.
Override if you need to set initial params.
doView
Controls what happens immediately
before the portlet is displayed in view
mode. Normally you override this.
doHelp, doEdit
Other portlet display modes
processAction
Place for handling any <form> actions
before turning over to the display mode
method (like doView). You should override
this for web forms.
Some Supporting Classes/Interfaces
Class
Description
PortletContext
Similar to servlet context; get context info and
the RequestDispatcher from here.
PortletSession
Stores attribute information for a single portlet
application across multiple requests.
RenderRequest,
RenderResponse
The request and response objects available to
the doView() method. Similar to the normal
servlet request
ActionRequest,Actio
nResponse
The request and response objects available to
the processAction() method. Similar to the
servlet request and response objects.
PortletURL
Use this to create URLs that reference the portal.
PortletRequestDispa
tcher
Use this to include/forward to a JSP or servlet in
the same portlet app.
WindowState
See if you are in minimized, maximized, normal
state.
The Big Picture


As a portlet developer, the previous set of classes are all you
normally touch.
The portlet container is responsible for running your portlets.
• Init, invoke methods, destroy.

Portlets have a very limited way of interacting with the
container.
• The API is basically one-way.
In Action: Get started.
public class JunkPortlet extends GenericPortlet {
public void init(){
//Do any initialization.
}
//Rest of the methods on following slides go
here.
…
}
Override doView()
protected void doView( RenderRequest req, RenderResponse
res)
throws PortletException, IOException {
//Include the desired JSP or HTML page.
//We could also use out to write directly to the response.
WindowState state=req.getWindowState();
if(!state.equals(WindowState.MINIMIZED)) {
res.setContentType("text/html");
PortletRequestDispatcher rd=
getPortletContext().getRequestDispatcher(“MyJSP.jsp
”);
rd.include(req,res);
}
}
The JSP Page
<portlet:defineObjects/>
<%
PortletSession
portletSession=renderRequest.getPortletSession();
portletSession.setAttribute("localattname","localattval");
PortletURL url=renderResponse.createActionURL();
String theActionString=url.toString();
%>
HTML Content is here.
A form is below.
<form method=post action="<%=theActionString%>">
<input type=…>
</form>
Some Notes
• Include the <%portlet:definedObjects/%> tag, which will
instantiate renderRequest, renderResponse, and
portletConfig objects.
– You can then just use them, as with request, response, and other
JSP implicit objects.
• The renderRequest gives you access to the PortletSession,
if you want to store session variables.
– One of the trouble points.
• The renderResponse gives you access to the PortletURL
object.
• Use the PortletURL to generate a URL for the <form
action>
– So that it points to portlet container and gets handled by the
processAction() method, rather than going of into space.
– Handle href URLs similarly.
– This is one of the sticking points.
Lastly, Override processAction()
• When you invoke the form on
the previous JSP, the portlet
container will pass the action
handling to the processAction
method.
• The ActionRequest can be used
to get any of the <input>
parameters in a way similar to
the usual HttpServletRequest.
• When the processAction
method returns, the container
then invokes the appropriate do
method (usually doView).
• If you need to pass <form>
parameters on to doView, add
them to the ActionResponse.
– This will give them to the
RenderRequest.
– The example shows how to
add ALL parameters.
public void processAction
(ActionRequest request,
ActionResponse
actionResponse) throws
PortletException,
java.io.IOException {
//Process request parameters
…
//Add other params
// to the renderRequest
actionResponse.setRenderPar
ameters(request.getParameter
Map());
}
A Comment on Portlet Coding

JSR 168 seems to make some important and
dubious assumptions
• Developers will gladly ignore other development
methodologies/frameworks like Velocity, Struts, and Java
Server Faces.
• Developers instead want to write a GenericPortlet extension
for every single portlet they develop.

And write really complicated processAction() and doView()
methods.
• Developers will like the specific JSR 168 portlet-style
Model-View-Controller that it forces on them.

Fortunately, these other development environments
can be mapped to portlet actions.
• In the OGCE project, we have developed support for
Velocity portlets.
• We are transitioning to Java Server Faces
A Grid Portlet Scenario
Developing a Simple Grid
Portlet Application
A Quantum Chemistry Code
Submission Form


You have been asked to develop a
submission form for the Democritos
group’s Quantum Espresso (QE) package.
These forms should help users set up and
run QE applications on the TeraGrid and
other Grid installations.
• Mix of GT 2, GT 4, Condor, etc., for submission


You are told to initially support the Plane
Wave Self Consistent Field (PWSCF) code.
Other QE applications may follow.
• These may be coupled with PWSCF into simple
workflows, but this is a later problem.
Your Deployment Architecture
Your portal
server runs
at FSU.
It acts as a common Gateway to
different grid toolkit
installations and resources
GT 4
@TG
TeraGrid
LSF
GT 2
@UMN
MSI
PBS
Portal
Server
@FSU
Some Issues

You decide the JSR 168 style portlets are
the way to go…
• But of course the PWSCF portlet doesn’t exist
yet.

You will need to also support other
Quantum Espresso codes.
• Would like to reuse as much code as possible.
• But your PWSCF portlet isn’t reusable at that
level.

You also would like to simplify saving user
input data and session archiving.
PWSCF Web Forms for
Submission
Your Choices



JSR 168 will allow you to share your portlet code
with other collaborators.
The Java COG Kit will help hide the differences
between Grid toolkits for common tasks.
Vanilla JSF will help simplify your portlet
development in several ways.
• JSF decouples your backing code from the Servlet API


You can write your backing code as pure Java Beans/Plain Old
Java Objects.
You don’t have to adopt, maintain HTTP parameter name
conventions.
• Your form input backing beans can be serialized/deserialized
with Castor.

Coupling JSF and COG will allow you to compose
your Grid actions using simple JSF taglibs.
• You can reuse your Grid taglibs in other Quantum Espresso
portlets.
• You can compose composite actions
The Java CoG Kit
Gregor von Laszewski
Argonne National Laboratory
University of Chicago
[email protected]
http://www.cogkit.org
(as interpreted by MEP)
CoG Kits


CoG Kits make Grid programming simple and
new technologies are easy to integrate
We focus on a CoG Kit for Java
• Python also available (K. Jackson, LBNL)
• Availability: Java CoG Kit since 1997

The CoG provides two important things
• A higher level client programming environment
than stubs.
• A shield against different versions of the Globus
toolkit

Same high level API works with GT 2.4, GT 3.0.2, GT
3.2.0, GT 3.2.1, GT 4.0.0
CoG Abstraction Layers
Nano
materials
BioDisaster
Informatics
Management
Applications
Portals
Development
Support
CoGGridfaces
GridfacesLayer
Layer
CoG
CoG
CoG GridIDE
GridIDE
CoGData
Dataand
andTask
TaskManagement
ManagementLayer
Layer
CoG
CoGAbstraction
AbstractionLayer
Layer
CoG
CoG
CoG
GT2
CoG
CoG
GT3
OGSI
classic
CoG
CoG
GT4
WS-RF
CoG
CoG
CoG
CoG
Condor Unicore
CoG
CoG
SSH
CoG
CoG
Others
Avaki
SETI
Task
Handler
The class diagram
is the
same for all grid
tasks (running jobs,
modifying files,
moving data).
Task
Task
Specification
Service
Security
Context
Classes also abstract toolkit
provider differences. You set
these as parameters: GT2,
GT4, etc.
Service
Contact
Setting Up Task and Specification
Task task=new TaskImpl(“mytask”,
Task.JOB_SUBMISSION);
task.setProvider(“GT2”);
JobSpecification spec=
new JobSpecificationImpl();
spec.setExecutable(“rm”);
spec.setBatchJob(true);
spec.setArguments(“-r”);
…
task.setSpecification(spec);
Setting Up the Service and Security
Context
Service service=new
ServiceImpl(Service.JOB_SUBMISSION);
service.setProvider(“GT2”);
SecurityContext securityContext=
CoreFactory.newSecurityContext(“GT2”);
//Use cred object from ProxyManager
securityContext.setCredentials(cred);
service.setSecurityContext(
(SecurityContext)securityContext);
Set Up Service Contact and
Finish
ServiceContact serviceContact=
new ServiceContact(“myhost.myorg.org”);
service.setServiceContact(serviceContact);
task.setService(
Service.JOB_SUBMISSION_SERVICE,
service);
TaskHandler handler=new
GenericTaskHandler();
handler.submit(task);
Coupling CoG Tasks


The COG
abstractions also
simplify creating
coupled tasks.
Tasks can be
assembled into
task graphs with
dependencies.
• “Do Task B after
successful Task A”

Graphs can be
nested.
Java COG Summary

The Java COG 4 interfaces provide high level
abstractions for building Grid clients.
• Abstract out differences between Grid toolkits.
• Provide task abstractions that form the basis for
constructing DAG-style, file-based workflow.

The COG can be used to build a wide range of
clients
• Desktops, grid shells, and of course portals.
• Portlets are a well known way to build reusable
portal components.
Building Grid Portlets
with Java Server Faces
Limitations of Portlets

Portlets provide a way to bundle and share a
complete application.
• RSS portlet, GridFTP portlet, SRB portlet, etc.
• Portlets combine the user interface view and
action code.

But in science gateway development, we
often need finer grained components.
• “When user clicks button, upload file, launch code,
and move data someplace when done.”
• Combines “GridFTP” and “Job Submit” portlets…
• Or maybe OGSA-DAI or SRB or ….

We need a way for the view and action code
to be developed from reusable parts.
JSF and Science Gateways

JSF enables you to back your science
application input form portlets with Java
Beans.
• These are independent of the servlet container, so
are easy to test and to reuse in other applications.

But also, Java Beans can be easily serialized
with XML.
• Castor, XML Beans
• Marshal and un-marshal user input for persistent
storage in XML storage services

OGSA-DAI, GPIR, WS-Context
• Potentially, can develop backing code as XML
Schema and generate the code.
JSF for Grid Enabled HTML
Widgets

Natural program: develop Java Bean
wrappers around Java COG kit, OGSA-DAI
client API, SRB Jargon, etc.
• Allows simple integration with JSF.

Some issues exist
• JSF only manages individual bean instances.
• But grid portlets will need to manage an unknown
number of bean instances.

You may launch and monitor many different jobs.
• We need a way of scripting composite actions
created out of multiple reusable actions.
COG Bean Wrappers

Recall the COG structure
• Executable tasks abstract basic grid
actions and hide toolkit version
differences.
• These tasks can be collected into filebased DAG workflows.

First problem is simple: wrap tasks as
beans to make them available to JSF.
• GenericGridBean defines the interface

Second problem is managing multiple
individual tasks.
Managing Multiple Grid Tasks

We must create and manage multiple beans
for each task.
• That is, I submit the job four times in one session.
• Similarly, we can create multiple task graph
clones.


We do this by cloning and storing each bean.
Beans have listeners and maintain state.
• Unsubmitted, submitted, active, suspended,
resumed are “live”

Stored in live repository
• Failed, canceled, completed, unknown are “dead”


Stored in archive (WS-Context or other)
Alternative approach: use one bean that is a
bean factory for GenericGridTask beans.
Corresponding JSF snippets
<o:taskGraph id="myGraph" method="#{taskgraph.test}" >
<o:task id="task1" method="task.create"
type="FileTransfer" />
<o:task id="task2" method="task.create"
type="JobSubmit" />
<o:task id="task3" method="task.create"
type="FileTransfer" />
<o:taskAdd name="task1" method="taskgraph.add" />
<o:taskAdd name="task2" depends="task1“
method="taskgraph.add" />
<o:taskAdd name="task3" depends="task2"
method="taskgraph.add" />
</o:taskGraph>
<h:panelGrid columns="2">
<h:commandButton id="submit" value="Submit"
action="#{taskgraph.submitAction}"/>
<h:commandButton value="Clear" type="Reset"/>
</h:panelGrid>
<h:panelGrid columns="3" >
<h:outputText value="Hostname (*) "/>
<h:inputText
value="#{task.hostname}"/>
</h:panelGrid>
<h:panelGrid columns="3" >
<h:outputText value="Provider (*) "/>
<h:inputText value="#{task.provider}"/>
</h:panelGrid>
Task Monitoring with JSF
Data Model
Corresponding Java class.
public class Job {
private String jobId;
private String status;
private String submitDate;
private String finishDate;
}
<h:dataTable value="#{jobData.jobs}" var="job">
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Job ID" />
</f:facet>
<h:outputText value="#{job.jobId}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Submit Date"
/>
</f:facet>
<h:outputText value="#{job.submitDate}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Finish Date"
/>
</f:facet>
<h:outputText value="#{job.finishDate}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Status" />
</f:facet>
<h:outputText value="#{job.status}"/>
</h:column>
</h:dataTable>
Using AJAX
Galip Aydin, Ahmet Sayar, and
Marlon Pierce
Community Grids Lab
Indiana University
What Is AJAX?

Asynchronous JavaScript and XML is a combination
of standard Web technologies
• JavaScript, CSS, DOM, XML

When done properly, it provides apparently seamless
interactivity in browser clients.
• No browser reloads
• Much smoother than standard request-wait-response for
browser forms.

Several Google tools are a very well known
examples.
• Google maps, Gmail, etc.

The real key is the standardization of the
XMLHttpRequest Object
• Originally developed for Internet Explorer
• Now supported by all major browsers.

Seminal article from Adaptive Path
• http://www.adaptivepath.com/publications/essays/archives/
000385.php
AJAX Architecture
Taken from http://www.adaptivepath.com/publications/essays/archives/000385.php
The Main Idea: Asynchronous
JavaScript Calls to Server

AJAX’s key concept is the use of
XMLHttpRequest to buffer requests and
responses within the browser.
• Use XMLHttpRequest to make a call to the server
and get back the response without displaying it.
• The response is stored locally as either plain text
(plain or HTML), or XML.
• JavaScript + DOM can be used to walk the HTML
or XML tree to handle most user interactions.

The XMLHttpRequest object in turn can issue
requests and process responses
independently of the user’s interaction.
• Go and fetch additional maps, for example.
Asynchronous Invocations
How it Works
Simple Example: GIS and Google
Maps

The Web Feature Service is a standard
geographical information system service.
• It stores geographic features and metadata used
to construct maps.
• Features are represented with the Geographic
Markup Language
• For example, the location and properties of
earthquake faults and seismic events.



The Feature Service is typically constructed
around traditional request-response.
We would like to combine this with Google
Maps to make more interactive user
interfaces.
So let’s get started.
Integrating Google Maps and GIS
Services
Simple Architecture
Client
MAP interface
Supported
Feature Data
by the WFS
Google Map
Server
OGC WFS
Feature Data Server
Layer specific
parameters
for filtering
Making the request

Creating an XMLHttpRequest Object
• For any browser, except IE

var requester = new XMLHttpRequest();
• In IE


var requester = new ActiveXObject("Microsoft.XMLHTTP");
Transporting Data using an XMLHttpRequest
Object
• To retrieve data from the server we use two methods:
open() to initialize the connection,
send() to activate the connection and make the
request.
requester.open("GET", "getFaultNames.jsp?State=CA");
requester.send(null);

This request is for all California fault information
in the Feature Service.
• It will be encoded in GML
• It may take a bit of time to download….
Checking the Connection Status

To find out if the data retrieval is done we check
the status of the readyState variable. Object’s
status may be any of the following:
0
1
2
3
4
–
–
–
–
–
Uninitialised
Loading
Loaded
Interactive
Completed
• requester.onreadystatechange monitors the readyState
variables status.
if (requester.readyState == 4){
if (requester.status == 200){
success();
}
else{
failure();
}
}
Parsing the Data


After a successful request XMLHttpRequest object may hold
data in one of the two properties: responseXML or
responseText.
responseXML stores a DOM-structured XML data.
<Fault>
<Name>San Andreas</Name>
</Fault>

We use JavaScript XML parsing methods such as
getElementsByTagName(), childNodes[], parentNode…
var faultNameNode =
requester.responseXML.getElementsByTagName(“Name")[0];
var faultName = faultNameNode.childNodes[0].nodeValue;


We can then use Google Map JavaScript functions to create
the browser display.
responseText stores the data as one complete string in
case the content type of the data supplied by the server
was text/plain or text/html.
Ajax Calls From JSP Pages

In the 1st JSP page
function checkForMessage()
{
var url = "relay.jsp";
initRequest(url);
req.onreadystatechange =
processReqChange;
req.open("GET", url,
true);
req.send(null);
}

The request is
forwarded to relay.jsp

In the 2nd JSP page
(relay.jsp)
<%
Bean.getNames(response);
%>

The response object
will contain the XML
result object.
Integrating Web
Feature Service
Archives and
Google Maps
Google maps can be
integrated with Web
Feature Service
Archives to browse
earthquake fault
records.
Faults are typically stored by segment number, so map
interfaces are convenient for both verifying continuity
and setting up input files for computing problems.
Other Useful Examples

AJAX is also useful for simulating server
data pushing.
• Browser interface is updated periodically from
locally stored data.
• XMLHttpRequest periodically requests updates
asyncrhonously.



Replace annoying browser reload polling
and fragile, non-standard server push.
The browser is always available for user
interactions while the XMLHttpRequest
object is being updated.
Examples: Chat applications and GPS
streams
Real Time GPS
and Google Maps
Subscribe to live GPS
station. Position data
from SOPAC is
combined with Google
map clients.
Select and zoom to
GPS station location,
click icons for more
information.
Conclusions

Computing portals  scientific gateways.
• Gateways include both user interface components
and supporting services.
• Manage user interactions with Grid infrastructure.

We reviewed standards for building portals
out of reusable components.
• JSR 168 portlet standard

Several new techniques can be used to build
portlets.
• Java Server Faces: reusable components for
portlets.
• AJAX: better interactivity for portlets
More Information


[email protected]
Open Grid Computing Environments
• http://www.collab-ogce.org

Geographical Information System
services
• http://www.crisisgrid.org

QuakeSim
• http://quakesim.jpl.nasa.gov
Integrating JSF and COG 4
Mehmet Nacar and Marlon Pierce
JSF for Grid Enabled HTML
Widgets
• Natural program: develop Java Bean wrappers
around Java COG kit, OGSA-DAI client API, SRB
Jargon, etc.
– Allows simple integration with JSF.
• Some issues exist
– JSF only manages individual bean instances.
– But grid portlets will need to manage an unknown
number of bean instances.
• You may launch and monitor many different jobs.
– We need a way of scripting composite actions created
out of multiple reusable actions.
COG Bean Wrappers
• Recall the COG structure
– Executable tasks abstract basic grid actions and
hide toolkit version differences.
– These tasks can be collected into file-based
DAG workflows.
• First problem is simple: wrap tasks as beans
to make them available to JSF.
– GenericGridBean defines the interface
• Second problem is managing multiple
individual tasks.
JSF Task Management Class
Structure
«interface»
GenericGridBean
TaskListenerBean
1
TaskGraphListenerBean
1
TaskBeanManager
TaskGraphBeanManager
*
*1
1*
TaskBean
TaskGraphBean
1
*
*
Managing Multiple Grid Tasks
• We must create and manage multiple beans for
each task.
– That is, I submit the job four times in one session.
– Similarly, we can create multiple task graph clones.
• We do this by cloning and storing each bean.
• Beans have listeners and maintain state.
– Unsubmitted, submitted, active, suspended, resumed are
“live”
• Stored in live repository
– Failed, canceled, completed, unknown are “dead”
• Stored in archive (WS-Context or other)
• Alternative approach: use one bean that is a bean
factory for GenericGridTask beans.
Managing Multiple Tasks
HashMap
JSF Form
Task Manager
JSF
retrieve
Task Bean 1
Task Bean 2
Task Bean
register
JSF
Task Bean 3
Managed Beans
Creating Task Graphs
• COG Task Graphs correspond to composite
JSF Web Form actions.
– Do X, Y, and then Z when user clicks the button.
• Each of these actions may be reused, but the
entire action is new.
• We must do two things
– Wrap the COG TaskGraphHandler with a bean
and bean manager.
– Provide tag bindings for defining the custom
actions.
Constructing Task Graphs
JSF Request Form
HashMap
TaskGraph Manager
JSF
retrieve
TaskGraph 1
register
TaskGraph 2
TaskGraphBean
JSF Monitoring
Form
TaskGraph 3
JobSubmit Bean
FileTransfer Bean
FileOperation Bean
Managed Beans
Expressing Task Graphs with Tags
<%@taglib uri="http://java.sun.com/jsf/core" prefix="f"%>
<%@taglib uri="http://java.sun.com/jsf/html" prefix="h"%>
<%@taglib uri="http://www.ogce.org/gsf/task" prefix="o"%>
………
………
<o:taskGraph id="myGraph" method="#{taskgraph.test}" >
<o:task id="task1" method="task.create" type="FileTransfer" />
<o:task id="task2" method="task.create" type="JobSubmit" />
<o:task id="task3" method="task.create" type="FileTransfer" />
<o:taskAdd name="task1" method="taskgraph.add" />
<o:taskAdd name="task2" depends="task1" method="taskgraph.add" />
<o:taskAdd name="task3" depends="task2" method="taskgraph.add" />
</o:taskGraph>
Corresponding JSF snippets
<o:taskGraph id="myGraph" method="#{taskgraph.test}" >
<o:task id="task1" method="task.create"
type="FileTransfer" />
<o:task id="task2" method="task.create"
type="JobSubmit" />
<o:task id="task3" method="task.create"
type="FileTransfer" />
<o:taskAdd name="task1" method="taskgraph.add" />
<o:taskAdd name="task2" depends="task1“
method="taskgraph.add" />
<o:taskAdd name="task3" depends="task2"
method="taskgraph.add" />
</o:taskGraph>
<h:panelGrid columns="2">
<h:commandButton id="submit" value="Submit"
action="#{taskgraph.submitAction}"/>
<h:commandButton value="Clear" type="Reset"/>
</h:panelGrid>
<h:panelGrid columns="3" >
<h:outputText value="Hostname (*) "/>
<h:inputText
value="#{task.hostname}"/>
</h:panelGrid>
<h:panelGrid columns="3" >
<h:outputText value="Provider (*) "/>
<h:inputText value="#{task.provider}"/>
</h:panelGrid>
Task Monitoring with JSF
Data Model
Corresponding Java class.
public class Job {
private String jobId;
private String status;
private String submitDate;
private String finishDate;
}
<h:dataTable value="#{jobData.jobs}" var="job">
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Job ID" />
</f:facet>
<h:outputText value="#{job.jobId}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Submit Date"
/>
</f:facet>
<h:outputText value="#{job.submitDate}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Finish Date"
/>
</f:facet>
<h:outputText value="#{job.finishDate}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText style="font-weight: bold" value="Status" />
</f:facet>
<h:outputText value="#{job.status}"/>
</h:column>
</h:dataTable>
Extended Slides
The Java CoG Kit
Gregor von Laszewski
Argonne National Laboratory
University of Chicago
[email protected]
http://www.cogkit.org
(as interpreted by MEP)
CoG Kits
• CoG Kits make Grid programming simple and new
technologies are easy to integrate
• We focus on a CoG Kit for Java
– Python also available (K. Jackson, LBNL)
– Availability: Java CoG Kit since 1997
• The CoG provides two important things
– A higher level client programming environment than
stubs.
– A shield against different versions of the Globus toolkit
• Same high level API works with GT 2.4, GT 3.0.2, GT 3.2.0, GT
3.2.1, GT 4.0.0
CoG Abstraction Layers
Nano
materials
BioDisaster
Informatics
Management
Applications
Portals
Development
Support
CoGGridfaces
GridfacesLayer
Layer
CoG
CoG
CoG GridIDE
GridIDE
CoGData
Dataand
andTask
TaskManagement
ManagementLayer
Layer
CoG
CoGAbstraction
AbstractionLayer
Layer
CoG
CoG
CoG
GT2
CoG
CoG
GT3
OGSI
classic
CoG
CoG
GT4
WS-RF
CoG
CoG
CoG
CoG
Condor Unicore
CoG
CoG
SSH
CoG
CoG
Others
Avaki
SETI
Task
Handler
The class diagram
is the
same for all grid
tasks (running jobs,
modifying files,
moving data).
Task
Task
Specification
Service
Security
Context
Classes also abstract toolkit
provider differences. You set
these as parameters: GT2,
GT4, etc.
Service
Contact
Java COG Summary
• The Java COG 4 interfaces provide high level
abstractions for building Grid clients.
– Abstract out differences between Grid toolkits.
– Provide task abstractions that form the basis for
constructing DAG-style, file-based workflow.
• The COG can be used to build a wide range of
clients
– Desktops, grid shells, and of course portals.
– Portlets are a well known way to build reusable portal
components.
Building Grid Portlets with
Java Server Faces
Limitations of Portlets
• Portlets provide a way to bundle and share a
complete application.
– RSS portlet, GridFTP portlet, SRB portlet, etc.
– Portlets combine the user interface view and action code.
• But in science gateway development, we often need
finer grained components.
– “When user clicks button, upload file, launch code, and
move data someplace when done.”
– Combines “GridFTP” and “Job Submit” portlets…
– Or maybe OGSA-DAI or SRB or ….
• We need a way for the view and action code must
be developed from reusable parts.
PWSCF Web Forms for
Submission
Java Server Faces Overview
• JSF can solve the reusable portlet widget
problem.
– JSF can also work in “standalone” mode outside
of portlets.
– Potentially independent of Web applications.
• XUL and Swing widget bindings
• We will first examine JSF generally
• Conclude with integrating JSF and COG
Advantages of JSF
• JSF hides communication details that connect
HTML forms with backing code.
– You don’t have to worry about servlet specific request,
response, and session objects.
– You don’t have to maintain fragile naming conventions for
<input> tags.
• Developers only need to develop JavaBeans and
tag libraries.
– Beans are independent of Web applications.
– Can be easily written and tested outside of servlet
containers.
– Compatible popular “Inversion of Control” based systems
like JSF and Spring
JSF and Science Gateways
• JSF enables you back your science application input
form portlets with Java Beans.
– Again, these are independent of the servlet container, so
are easy to test and to reuse in other applications.
• But also, Java Beans can be easily serialized with
XML.
– Castor, XML Beans
– Marshal and un-marshal user input for persistent storage in
XML storage services
• OGSA-DAI, GPIR, WS-Context
– Potentially, can develop backing code as XML Schema and
generate the code.
A JSF Example
<HTML>
<HEAD> <title>Hello</title> </HEAD>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<body bgcolor="white">
<f:view>
<h:form id="entryForm" >
<h2> Enter some text in the form below</h2>
<h:inputText id="userSt"
value="#{multiEventBean.userString}"/>
<h:commandButton id="submit"
action="success" value="Submit" >
<f:actionListener type="multiEventTest.Listener1"/>
<f:actionListener type="multiEventTest.Listener2"/>
</h:commandButton>
</h:form>
</f:view>
</body>
</HTML>
The JSF Page
• Note everything with <f:> or <h:> namespace prefix is a JSF
tag.
– Usually, <h:> tags mimic HTML widgets.
– <f:> is for non-rendered stuff.
– Everything else is good old HTML.
• There are three different Java classes here.
– They are all in the package multiEventTest
– multiEventBean.java is just a bean with typical get/set methods.
– Listener1.java and Listener2.java implement the
javax.faces.event.ActionListener interface.
• All 3 classes are called when you click the command button.
• Also, take a look at <inputText>. This is roughly equivalent
to <input name=“” value=“”>.
– But no name needed. JSF handles parameter names for you and
connects them to the beans you specify.
– This greatly simplifies writing generic actions.
A Simple Example: HtmlDataGrid
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<f:view>
<h2> This shows an example of how to use
HtmlDataTable to display some results.
</h2>
<h:dataTable value="#{ValueBean.itemList}" var="values" border="1">
<h:column>
<f:facet name="header">
<h:outputText value="Column 1"/>
</f:facet>
<h:outputText value="#{values.value1}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Column 2"/>
</f:facet>
<h:outputText value="#{values.value2}"/>
<h:outputText value="#{values.value2}"/>
</h:column>
</h:dataTable>
</f:view>
It Looks Like This
Some Explanation
• The <h:dataTable> binds to a particular data set with
value=“ValueBean.itemList”.
– ValueBean.itemList must be java.util.List, java.sql.ResultSet or
similar.
– The values of these lists may be beans also.
• The var=“” just defines a useful internal value.
– Here, each entry in the list is set equal to “values”.
– In the example, the items in the list happen to be simple beans with
member variables “value1” and “value2” along with appropriate
getter/setters.
• When you load the page, it just iterates through the entries
in ValueBean.itemList and creates the table, as you
instructed.
• Note again there are no loops in the actual page. Also, you
don’t know anything about the data you are getting.
JSF Magic: Data Models
• The M in MVC is the Data Model
– “Abstract” representation of a data structure
• That is, not tied to the display of the data (“view”)
• JSF DataModel extension classes include
–
–
–
–
–
Arrays: wrap arrays of Java objects
Lists: wraps a java.util.List of Java objects
Results: for JSTL’s Result object, which itself wraps SQL ResultSets.
ResultSets: also for JDBC, wraps the ResultsSet object directly.
Scalar: Wraps an individual Java object.
• Typically, these should follow Bean patterns for naming member data
and their associated getter/setters.
• You can write your own specialized Data Models.
– XMLDataModel, for wrapping an XML data bean, comes to mind.
– RSSDataModel is another that I found.
• These are associated with UIData classes in the JSF page for display.
– HtmlDataTable is an example.
JSF Form Validators
• The user interface stuff (<f:> and <h:>) has
lots of built-in validators
– Verify that input entries are integers, doubles, etc.
– Verify that input entries fall within the correct
range (1 to 10 in the guessNumber example).
– Verify the string has the right length.
• You can extend to write your own specialized
validators