GT3 Tutorial Chapter 3 and Chapter 4

1
GT3 TutorialChapter 3 and Chapter 4

• Lecture for Cluster and Grid Computing, CSCE
  490/590
• Fall 2004, University of Arkansas, Dr. Amy Apon
• http//csce.uark.edu/aapon/courses/gridcomputing/
  index.html
• from
• http//www.casa-sotomayor.net/gt3-tutorial/

2
Chapter 3 Writing your first Grid Service

• Math Service
• Will perform two operations, addition and
  subtraction

3
Before you start

• Download the tutorial source files to your
  account on talon.csce.uark.edu
• http//www.casa-sotomayor.net/gt3-tutorial/downloa
  d/progtutorial-examples_0.4.2.tar.gz

4

• TUTORIAL_DIR
• -- schema/
• -- progtutorial/ -----gt GWSDL files
• --- org/
• -- globus/
• -- progtutorial/
• -- services/
  -----gt Service impL files
• -- clients/ -----gt
  Client impl files

5
Five Steps

• Define the service's interface. This is done with
  GWSDL
• Implement the service. This is done with Java
• Define the deployment parameters. This is done
  with WSDD
• Compile everything and generate GAR file. This is
  done with Ant
• Deploy service. This is also done with Ant

6
Step 1 Define the interface in GWSDL Two
options

• Writing the WSDL directly.
• This is the most versatile option.
• Total control over the description of our
  portType.
• Generating WSDL from a Java interface.
• The easiest option, but very complicated
  interfaces are not always converted correctly to
  WSDL

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The interface in Java

• public interface Math
• public void add(int a)
• public void subtract(int a)
• public int getValue()
• Notice there is only one parameter!?!

8
Steps to GWSDL (Grid WSDL)

• Write the root element ltdefinitionsgt
• Write the ltgwsdlPortTypegt
• Write an input and output ltmessagegt for each
  operation in the PortType.
• Write the lttypesgt

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a. Write the root element

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltdefinitions name"MathService"
• targetNamespace"http//www.globus.org/namespaces
  /2004/02/progtutorial/MathService"
• xmlnstns"http//www.globus.org/namespaces/2004/
  02/progtutorial/MathService"
• xmlnsogsi"http//www.gridforum.org/namespaces/2
  003/03/OGSI"
• xmlnsgwsdl"http//www.gridforum.org/namespaces/
  2003/03/gridWSDLExtensions"
• xmlnsxsd"http//www.w3.org/2001/XMLSchema"
• xmlns"http//schemas.xmlsoap.org/wsdl/"gt

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ltdefinitions gt

• name the name of the GWSDL file. Not related
  with the name of the PortType
• targetNamespace The target namespace of the
  GWSDL file.

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ltimport gt

• ltimport location"../../ogsi/ogsi.gwsdl"
  namespace"http//www.gridforum.org/namespaces/200
  3/03/OGSI"/gt

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b. Write the PortType

• ltgwsdlportType name"MathPortType"
  extends"ogsiGridService"gt
• ltoperation name"add"gt
• ltinput message"tnsAddInputMessage"/gt
• ltoutput message"tnsAddOutputMessage"/gt
• ltfault name"Fault" message"ogsiFaultMessage"/
  gt
• lt/operationgt
• ltoperation name"subtract"gt
• ltinput message"tnsSubtractInputMessage"/gt
• ltoutput message"tnsSubtractOutputMessage"/gt
• ltfault name"Fault" message"ogsiFaultMessage"/
  gt
• lt/operationgt
• ltoperation name"getValue"gt
• ltinput message"tnsGetValueInputMessage"/gt
• ltoutput message"tnsGetValueOutputMessage"/gt
• ltfault name"Fault" message"ogsiFaultMessage"/
  gt
• lt/operationgt
• lt/gwsdlportTypegt

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portType tag important attributes

• name name of the PortType
• extends
• One of the main differences with plain WSDL.
• Allow definition of PortType as an extension of
  an existing PortType.
• Extend from ogsiGridService PortType, which all
  Grid Services must extend from.

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Inside portType

• An ltoperationgt tag for each method in the
  PortType
• Operation tag has an input tag, an output tag,
  and a fault tag

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c. Write input and output messages for each port
type

• ltmessage name"AddInputMessage"gt
• ltpart name"parameters" element"tnsadd"/gt
• lt/messagegt
• ltmessage name"AddOutputMessage"gt
• ltpart name"parameters" element"tnsaddResponse"
  /gt
• lt/messagegt
• Message are composed of parts our messages have
  one part, in which a single XML element is passed
  along

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d. Define the XML elements inside the lttypesgt tag

• lttypesgt
• ltxsdschema targetNamespace"http//www.globus.org
  /namespaces/2004/02/progtutorial/MathService"
• attributeFormDefault"qualified"
• elementFormDefault"qualified"
• xmlns"http//www.w3.org/2001/XMLSchema"gt
• ltxsdelement name"add"gt
• ltxsdcomplexTypegt
• ltxsdsequencegt
• ltxsdelement name"value" type"xsdint"/gt
  lt/xsdsequencegt
• lt/xsdcomplexTypegt
• lt/xsdelementgt
• ltxsdelement name"addResponse"gt
• ltxsdcomplexType/gt
• lt/xsdelementgt
• lt/xsdschemagt
• lt/typesgt

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The whole GWSDL file

• http//www.casa-sotomayor.net/gt3-tutorial/multipl
  ehtml/apas01.html

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WSDL and GWSDL

• GWSDL has certain features that WSDL 1.1 doesn't
  have, but which will be available in WSDL 1.2/2.0
  (still a W3C working draft)
• GWSDL is a temporary solution
• First improvement not using the WSDL ltportTypegt
  tag, but a tag from the GWSDL namespace
  ltgwsdlportTypegt that extends
• Can extend from one or more portTypes
• Second improvement is related to Service Data

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Five Steps

• Define the service's interface. This is done with
  GWSDL
• Implement the service. This is done with Java
• Define the deployment parameters. This is done
  with WSDD
• Compile everything and generate GAR file. This is
  done with Ant
• Deploy service. This is also done with Ant

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Step 2 Implement the Service

• Implement the service MathImpl and place in
• TUTORIAL_DIR/org/globus/progtutorial/services/cor
  e/first/impl/MathImpl.java

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MathImpl.java

• package org.globus.progtutorial.services.core.firs
  t.impl
• import org.globus.ogsa.impl.ogsi.GridServiceImpl
  
• import org.globus.progtutorial.stubs.MathService.M
  athPortType
• import java.rmi.RemoteException
• public class MathImpl extends GridServiceImpl
  implements MathPortType
• MathImpl is a child class of GridServiceImpl
• All Grid Services extend GridServiceImpl.
• This is what is usually called the skeleton class
  
• Our Grid Service implements an interface named
  MathPortType
• one of the stub files which will be generated
  from the GWSDL file once we compile the service

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• public class MathImpl extends GridServiceImpl
  implements MathPortType
• private int value 0
• public MathImpl()
• super("Simple MathService")
• public void add(int a) throws RemoteException
• value value a
• public void subtract(int a) throws
  RemoteException
• value value - a
• public int getValue() throws RemoteException
• return value

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Five Steps

• Define the service's interface. This is done with
  GWSDL
• Implement the service. This is done with Java
• Define the deployment parameters. This is done
  with WSDD
• Compile everything and generate GAR file. This is
  done with Ant
• Deploy service. This is also done with Ant

24
Step 3 Configure the deployment in WSDD

• Save a file called
• TUTORIAL_DIR/org/globus/progtutorial/services/cor
  e/first/server-deploy.wsdd

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• lt?xml version"1.0"?gt
• ltdeployment name"defaultServerConfig"
• xmlns"http//xml.apache.org/axis/wsdd/"
• xmlnsjava"http//xml.apache.org/axis/wsdd/provi
  ders/java"gt
• ltservice name"progtutorial/core/first/MathServic
  e" provider"Handler" style"wrapped"gt
• ltparameter name"name" value"MathService"/gt
• ltparameter name"className" value"org.globus.pr
  ogtutorial.stubs.MathService.MathPortType"/gt
• ltparameter name"baseClassName"
  value"org.globus.progtutorial.services.core.first
  .impl.MathImpl"/gt
• ltparameter name"schemaPath" value"schema/progt
  utorial/MathService/Math_service.wsdl"/gt
• lt!-- Start common parameters --gt
• ltparameter name"allowedMethods" value""/gt
• ltparameter name"persistent" value"true"/gt
• ltparameter name"handlerClass"
  value"org.globus.ogsa.handlers.RPCURIProvider"/gt
• lt/servicegt

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Root element

• lt?xml version"1.0"?gt
• ltdeployment name"defaultServerConfig"
  xmlns"http//xml.apache.org/axis/wsdd/"
  xmlnsjava"http//xml.apache.org/axis/wsdd/provid
  ers/java"gt

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Service name

• ltservice name"progtutorial/core/first/MathService
  " provider"Handler" style"wrapped"gt
• Specifies the location where our Grid Service
  will be found.
• Combined with the base address of Grid Service
  container, gives the full GSH of the Grid
  Service.
• For example, if we are using the GT3 standalone
  container, the base URL will probably be
  http//localhost8080/ogsa/services.
• Therefore, our service's GSH would be
• http//localhost8080/ogsa/services/progtutorial/c
  ore/first/MathService

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Service name again

• ltparameter name"name" value"MathService"/gt
• The service element has both a name attribute and
  a name parameter!

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className and baseClassName

• ltparameter name"className" value"org.globus.prog
  tutorial.stubs.MathService.MathPortType"/gt
• ltparameter name"baseClassName"
  value"org.globus.progtutorial.services.core.first
  .impl.MathImpl"/gt
• className refers to the interface that exposes
  all the functionality of the grid service
  (MathPortType)
• baseClassName is the class that provides the
  implementation for our grid service.

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WSDL file

• ltparameter name"schemaPath" value"schema/progtut
  orial/MathService/Math_service.wsdl"/gt
• Tells the grid service container where the WSDL
  file for this service can be found
• GWSDL is a (non-standard) extension of WSDL
• It must first be converted to WSDL so it can be
  truly interoperable with existing web services
  technologies.
• WSDL file (Math_service.wsdl) will be generated
  automatically by a GT3 tool when we compile the
  service.

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Common parameters

• lt!-- Start common parameters --gt
• ltparameter name"allowedMethods" value""/gt
• ltparameter name"persistent" value"true"/gt
• ltparameter name"handlerClass" value"org.globus.o
  gsa.handlers.RPCURIProvider"/gt
• Three parameters found in every grid service we
  program.

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Five Steps

• Define the service's interface. This is done with
  GWSDL
• Implement the service. This is done with Java
• Define the deployment parameters. This is done
  with WSDD
• Compile everything and generate GAR file. This is
  done with Ant
• Deploy service. This is also done with Ant

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Step 4 Create a GAR file with ANT

• Using those three files we wrote we generate a
  Grid Archive, or GAR file.
• This GAR file is a single file which contains all
  the files and information the grid services
  container need to deploy our service and make it
  available to the whole world.

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Creating a GAR

• Converting the GWSDL into WSDL
• Creating the stub classes from the WSDL
• Compiling the stubs classes
• Compiling the service implementation
• Organize all the files into a very specific
  directory structure
• Well have a detailed discussion on ant soon.

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Using the tutorial scripts

• ./tutorial_build.sh ltservice base directorygt
  ltservice's GWSDL filegt
• Run this from TUTORIAL_DIR
• A GAR file will be generated
• TUTORIAL_DIR/build/lib/org_globus_progtutorial_se
  rvices_core_first.gar

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Five Steps

• Define the service's interface. This is done with
  GWSDL
• Implement the service. This is done with Java
• Define the deployment parameters. This is done
  with WSDD
• Compile everything and generate GAR file. This is
  done with Ant
• Deploy service. This is also done with Ant

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Step 5 Deploy the service into a grid service

• GAR file contains all the files and information
  the web server needs to deploy the Grid Service
• ant deploy -Dgar.nameltfull path of GAR filegt
• For example, with the GAR just created
• ant deploy \ -Dgar.nameTUTORIAL_DIR/build/lib/or
  g_globus_progtutorial_services_core_first.gar

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A simple client

• package org.globus.progtutorial.clients.MathServic
  e
• import org.globus.progtutorial.stubs.MathService.s
  ervice.MathServiceGridLocator
• import org.globus.progtutorial.stubs.MathService.M
  athPortType
• import java.net.URL
• public class Client
• public static void main(String args)
• try
• // Get command-line arguments
• URL GSH new java.net.URL(args0)
• int a Integer.parseInt(args1)

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• // Get a reference to the MathService instance
• MathServiceGridLocator mathServiceLocator new
  MathServiceGridLocator()
• MathPortType math mathServiceLocator.getMathServ
  icePort(GSH)
• // Call remote method 'add' math.add(a)
• System.out.println("Added " a)
• // Get current value through remote method
  'getValue'
• int value math.getValue()
• System.out.println("Current value " value)
• catch(Exception e)
• System.out.println("ERROR!")
• e.printStackTrace()

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Compile the client

• source GLOBUS_LOCATION/etc/globus-devel-env.sh
• To put the Globus libraries into your CLASSPATH
• javac \ -classpath ./build/classes/CLASSPATH \
  org/globus/progtutorial/clients/MathService/Client
  .java

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Start the container (and the service)

• globus-start-container
• See if the following line appears in the list of
  services!
• http//127.0.0.18080/ogsa/services/progtutorial/c
  ore/first/MathService

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Execute the client

• java \
• -classpath ./build/classes/CLASSPATH \
  org.globus.progtutorial.clients.MathService.Client
  \ http//127.0.0.18080/ogsa/services/progtutoria
  l/core/first/MathService \
• 5
• If all goes well, you should see the following
• Added 5
• Current value 5

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Chapter 4Operation Providers

• The previous example showed implementation by
  inheritance
• public class MathImpl extends GridServiceImpl
  implements MathPortType
• Operation providers offer implementation by
  delegation

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Implementation by inheritanceMathImpl class has
to provide all the operations specified
45
Implementation by delegationThe operations of
PortType are in several classes.
46
Implementation by delegation

• The classes dont extend any base class
• The only implement an interface called Operation
  Provider
• We tell the Grid Service container that
  GridServiceImpl will supply the basic
  functionality
• done with the deployment descriptor

47
Cant extend another Java class and extend
GridServiceImpl
48
Can extend another Java class and implement
OperationProvider
49
Tradeoffs of implementation by delegation

• Favors more modular, uncoupled, and reusable
  designs
• Is somewhat more work to code than the
  inheritance approach
• Both approaches are not mutually exclusive
• Can implement part of portType in a class that
  extends from GridServiceImpl and then complete
  the implementation with operation providers

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Writing an operation provider

• Same GWSDL as before
• Implementation of service is a little different

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• public class MathProvider implements
  OperationProvider
• // Operation provider properties
• private static final String namespace
  "http//www.globus.org/namespaces/2004/02/progtuto
  rial/MathService"
• private static final QName operations
• new QName
• new QName(namespace, "add"),
• new QName(namespace, "subtract"),
• new QName(namespace, "getValue")
• private GridServiceBase base
• // Operation Provider methods
• public void initialize(GridServiceBase base)
  throws GridServiceException
• this.base base
• public QName getOperations() return
  operations

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Writing an operation provider

• The deployment descriptor is a little different
• See http//www.casa-sotomayor.net/gt3-tutorial/mul
  tiplehtml/ch04s03.html
• Client is the same