Project Demo Grid Notification

1
Project Demo-Grid Notification

• Presentation by
• Ben Zhang

2
Overview

• Project summary
• Notification Concept
• Go through steps of implementing a notification
  grid service
• Demo

3
Project Objective

• Show how Grid Notification works
• Idea
• Implement a Grid Service with a notification SDE.
  This Grid Service provides clients with stock
  quote and has a notification SDE storing the
  recent queried stock info. If there is a change,
  its subscribed clients should get the
  notification.

4
Background

• What are notification
• When there are some changes of service, the
  observable notifies all its subscribed observers
  of the changes.
• Notification approach
• Push approachallow data to travel along with the
  notification
• Pull approach data not travel along with the
  notification.

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Notification in GT3

• Notification in GT3 is closely related to service
  data. The clients don't subscribe to a whole
  service, but to a particular Service Data Element
  (SDE) in that service.
• Whenever a change happens the service will ask
  the SDE to notify its subscribers.
• GT3 only supports push notification. But a pull
  notification can be implemented by subscribing to
  a 'dummy SDE' with no data.

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Notification in GT3

• addListener This call subscribes the calling
  client to a particular SDE.
• notifyChange Whenever a change happens, the
  GridService will ask the SDE to notify its
  subscribers.
• deliverNotification The SDE notifies the
  subscribers that a change had happened.

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StockQuote Grid Service

• StockQuote Grid Service
• provides clients real-time stock info based on
  stock ticker. The info includes stocks last
  price, date, time, change, open price,daily
  high,daily low, volume, etc.
• Notification SDE
• stores the last stock info queried by clients
• has the follows fields
• Stock symbol
• Last price
• Date
• time

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Step1-define interface

• Define the service interface
• extends"ogsiGridService ogsiNotificationSource"
  , extend from a standard portType called
  NotificationSource which includes
  notification-related operations.
• Other changes comparing to our MathServiceSD
  service
• targetNamespacehttp//www.globus.org/namespa
  ces/bxz01Assignments/StockQuoteService
• xmlnstnshttp//www.globus.org/namespaces/bx
  z01Assignments/StockQuoteService
• xmlnsdatahttp//www.globus.org/namespaces/b
  xz01Assignments/StockQuoteService/StockSDE
• namespace"http//www.globus.org/namespaces/b
  xz01Assignments/StockQuoteService/StockSDE"/

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Step 2-service implementation

• Get real-time stock info from yahoo base on stock
  ticker(symbol).
• http//finance.yahoo.com/d/quotes.csv?e.csvfsl1
  d1t1c1ohgvsYHOO
• In the link, fsl1d1t1c1ohgv defines the format
  of querying result. (S-symbol, l-lastprice,
  d-date, t-time, c-change, o-openprice,
  h-dailyhigh, g-dailylow,v-volume)
• For example
• "YHOO",37.99,"11/29/2004","306pm",0.18,38.07,38.
  24,37.50,10358000

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Step2- (continue)

• When there is a change of StockDataSDE,
  StockDataSDE notify all its subscribers through
  notifyChange() method.
• public void setSymbol(String symbol) throws
  RemoteException
• this.symbol symbol.toUpperCase()
• getQuote() StockDataValue.setSymbol(symbol)
  
• StockDataValue.setLastPrice(Double.parseDouble
  (lastPrice)) StockDataValue.setDate(date1)
  StockDataValue.setTime(time1)
• StockDataSDE.notifyChange()

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Step3- Deployment Descriptor

• xmlnshttp//xml.apache.org/axis/wsdd/
• xmlnsjavahttp//xml.apache.org/axis/wsdd/provide
  rs/java
• e" provider"Handler" style"wrapped"
• (with notification)"/
• value"bxz01Assignments.services.StockQuoteService
  .impl.StockQuoteImpl"/
• nts.stubs.StockQuoteService.StockPortType"/
• Assignments/StockQuoteService/StockQuote_service.w
  sdl"/
• value"org.globus.ogsa.impl.ogsi.NotificationSourc
  eProvider"/
• value"org.globus.ogsa.handlers.RPCURIProvider"/

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Step 4- compile and deploy

• build the service
• ./build.sh bxz01Assignments/services/StockQuoteSer
  vice schema/bxz01Assignments/StockQuoteService/Sto
  ckQuote.gwsdl
• Deploy
• ant deploy -Dgar.name/home/bxz01/GridServices/bui
  ld/lib/bxz01Assignments_services_StockQuoteService
  .gar

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Step 5- Client Listener

• Class declaration
• public class ClientListener extends
  ServicePropertiesImpl implements
  NotificationSinkCallback
• extends ServicePropertiesImpl
• This class is the base class of GridServiceImpl
  which is intended for the server-side of our
  application. Atually, our "client" is both a
  client and a server, because it is going to make
  calls to StockQuoteService (to subscribe to the
  StockDataSDE), but also receive them
  (deliverNotification). So, our client needs a
  server infrastructure, which the
  ServicePropertiesImpl class provides.
• implements NotificationSinkCallback
• This interface must be implemented by classes
  that wish to subscribe to notifications. A
  deliverNotification method which is called by the
  Grid Service when a change is produced

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Step 5- (continue)

• Subscribe to a SDE.
• Can be done by NotificationSinkManager. Two
  simple steps startListening and addListener
• NotificationSinkManager
  notifManager NotificationSinkManager.getManager(
  )
• notifManager.startListening(Notifi
  cationSinkManager.MAIN_THREAD)
• String sink
  notifManager.addListener("StockData", null, GSH,
  this)
• addListener method specifies which service and
  SDE the client should subscribe. The parameters
  are follows
• The Service Data Element we want to subscribe to.
• A timeout (null--if we don't want to stop
  listening)
• The GSH of the Grid Service that has the Service
  Data Element we want to subscribe to
• The class which will take care of receiving the
  notifications

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Step 5- (continue )

• Implement deliverNotification method
• public void deliverNotification(ExtensibilityType
  any) throws RemoteException
• try
• // Service Data has changed. Show new
  data.
• ServiceDataValuesType serviceData
  AnyHelper.getAsServiceDataValues(any)
• StockDataType StockData (StockDataType)
  AnyHelper.getAsSingleObject(serviceData,
  StockDataType.class)
• // Write service data
• System.out.println("Current stock info
  ")
• System.out.println("symbol "
  StockData.getSymbol())
• System.out.println("lastPrice "
  StockData.getLastPrice())
• System.out.println("Date "
  StockData.getDate())
• System.out.println("Time "
  StockData.getTime())
• catch(Exception exc)
• System.out.println("ERROR!")
• exc.printStackTrace()

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Step 5- (continue )

• Unsubscribe client
• // Stop listening
• notifManager.removeListener(sink)
• notifManager.stopListening()

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Step 6 run command

• Compile client
• javac -classpath ./build/classes/CLASSPATH
  bxz01Assignments/clients/StockQuoteService/ClientL
  istener.java
• Start container
• globus-start-container -p 30000
• Run client
• java -classpath ./build/classes/CLASSPATH
  -Dorg.globus.ogsa.schema.roothttp//localhost300
  00/ bxz01Assignments.clients.StockQuoteService.Cli
  entListener http//talon.csce.uark.edu30000/ogsa/
  services/bxz01Assignments/StockQuoteService
• Notice we have to define a property called
  org.globus.ogsa.schema.root.

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StockQuote Demo
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References

• http//www.casa-sotomayor.net/gt3-tutorial/multipl
  ehtml/ch06s01.html
• http//www-unix.globus.org/toolkit/docs/3.2/core/

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Questions?