MS.NETGrid OGSI User Manual - EPCC
Contents
1. Ped Termination time for subscription instance TerminationTimeType termTime new TerminationTimeType Set the term time to contain appropriate value Set carry out the subscription subscribeResponse response notificationSourceService subscribe subscriptionExpression sinkLocator termTime response gives you access to the subscription instance created by the request MS NETGrid OGSIUserManual v2 0 30 The subscribeResponse object that is returned by the subscribe operation may be used to manage the subscription To de register interest in changes to the values of the subscribed service data elements call the destroy method of the subscription service instance The Notification source monitor client included as part of the distribution in Install dir NotificationSourceMonitor demonstrates more fully how to write client applications that utilise notification capabilities MS NETGrid OGSIUserManual v2 0 31 12 Example services As an example of using portTypes serviceData and persistent and transient services we provide a pair of demonstration services These are located in the install dir MS NETGrid Ogsi Container demoservices container The basicService subdirectory contains a persistent Grid Service that implements the GridService portType a transient version of this service and a factory for creating instances of the transi2. NeSC IEDCC Beto Centre T H Tim ral MS NETGrid OGSI User Manual Project Title MS NETGrid Document Title MS NETGrid OGSI User Manual Document Identifier MS NETGrid OGSIUserManual v2 0 Authorship Ally Hume Daragh Byrne Document History Personnel Date Summary Version EOCC 30 January 2004 EPCC Approved 2 0 EPCC 16 June 2003 EPCC Approved 1 0 MJJ 13 June 2003 Second Draft Changes and Comments 0 2 ACH 10 June 2003 First Draft 0 1 Approval List EPCC Project Leader Technical Staff Technical Reviewer Coach Mike Jackson Daragh Byrne Ally Hume Ali Anjomshoaa Neil Chue Hong Approval List Microsoft Research Limited Managing Director University Relations x 3 Andrew Herbert Fabien Petitcolas Van Eden Dan Fay Copyright 2004 The University of Edinburgh All rights reserved MS NETGrid OGSIUserManual v2 0 2 Contents dau 2 IM ono P 4 L 1 Product Licence 4 1 3 Project WWW Site ie eeeivesteeseseu esee tvt boe tha set ease eai Pe veo t evo eaae ooa S ve ERE Ce Fue e a seost 4 1 3 Support and Queries 1 ecce ee eee eres crees ee eene en nsss son e osooso voss sopes ososi sss 4 2 Unstallation P 5 3 Running a Demonstration Client eeeeeeee eee ee eee
3. lt grdServiceHandle xmins http www gridforum org namespaces 2003 03 0G5 d2p1 goodFrom 2003 06 1 6T 09 44 55 5392 001 ra d2p1 goodUntil infinity MS NETGrid OGSIUserManual v2 0 4 Class documentation Source code documentation is available in Microsoft Help format at install dir MS NETGrid doc API MS NETGridHelp chm MS NETGrid OGSIUserManual v2 0 8 S Writing a simple persistent service In this section we go through the stages required to write and deploy a simple persistent Grid service A persistent Grid service is one whose lifetime is managed by the OGSI container rather than the client Client lifetime managed Grid services are known as transient Grid services The development stages for persistent Grid services are 1 Write the service class that implements the functionality of the service 2 Wirite the proxy class that exposes the service s public methods 3 Compile the service class and proxy class into an assembly 4 Write a asmx file for the service 5 Configure the OGSI container 6 Install the service The Grid service we write here will be a persistent Grid service We will implement a single method called hello This method takes one argument called name and will return the string hello name n where name is the value of the name argument and n is an integer that starts at 1 and increments every time the method is called The Grid service will inherit additional m
4. xmlParams Create a service using the factory MyTransServiceFactoryNS LocatorType locator locator factoryService createService creation Console WriteLine Have a service the locator is n locator handle 0 MS NETGrid OGSIUserManual v2 0 20 Create service object MyTransService service new MyTransService Tell this service object the location of the service instance service Url locator handle 0 Use the service object Console WriteLine service hello Mike 2 Console WriteLine service hello Daragh Console WriteLine service hello Ally yz Destroy the transient service when finished Service destroy There are several points to note about the code o We construct an XML element called xmlParams that contains the data required by the factory creator class The schema of this element is specific to this particular factory other factories can use different schema for their creation service parameters o The creation parameters XML element is bundled inside a CreationType object that is passed as input to the factory s createService method o The Uri property of all transient services proxies must be set before any methods of the proxy are called The Url property must be set to the handle returned by the factory via the LocatorType object o The transient service can be destroyed when the cli
5. Notification monitor client application that 1s included as part of the distribution The service is located in the Install dir Ogsi Container debug directory 11 4 Writing clients of notification sources A list of notifiable service data names for a service that implements NotificationSourcePortType is obtained by getting the value of the ogsi notifiableServiceDataName service data element in the usual manner i e using the QueryHelper class to generate a find query and then using the findServiceData method of the client side proxies to obtain the values Once this list has been obtained a client can subscribe to notifications to changes to one of these service data elements via the subscribe method of NotificationSubscriptionPortType In the following example the notifiableNames collection contains the names of the service data elements that are to be subscribed to An Array List containing these names is ArrayList notifiableNames The service client side proxy as generated by WSDL exe NotificationSourceServcice notificationSourceService new NotificationSourceService XmlElement subscriptionExpression QueryHelper GenerateNotificationSubscriptionByNamesExpression notifiableNames E Set up the locator for the service SetUpSinkLocator is some code somewhere that sets up a new Locator with info about the sink LocatorType sinkLocator SetUpSinkLocator
6. OGSI container an entry must be added to the container s Web config file this file is located at lt oGSTContainer gt Web config For the transient service the following entry must be added to the lt gridServiceDeployment gt element of the Web config file lt gridServiceDeploymentDescriptor asmxProxyFileName MyTransService asmx ServiceClass MyGridServices MyTransServiceImpl assembly MyTransServices persistence transient gt lt gridServiceDeploymentDescriptor gt This contents of this element are similar to that shown in section 5 5 for the simple persistent service Notice the value of the persistence attribute is now transient For the factory service the following element must be added to the lt gridServiceDeployment gt element of the Web config file lt gridServiceDeploymentDescriptor asmxProxyFileName MyTransServiceFactory asmx MS NETGrid OGSIUserManual v2 0 18 serviceClass MyGridServices MyTransServiceFactoryImpl assembly MyTransServices persistence persistent gt lt The type of the service object to create lt serviceParameter name creationProvider value MyGridServices MyTransServiceFactoryCreator MyTransServices gt lt gridServiceDeploymentDescriptor gt The majority of this element is very similar to that for the transient service The lt serviceParameter gt element is new This eleme
7. SourcePortType is OgsiPortType typeof NotificationSourcePortType OgsiConstants OGSI NAMESPACE URI NotificationSource public class MyNotificationSourceServiceImpl PersistentGridServiceSkeleton Implementation code here You will need to add code to the proxy for you service that exposes the Subscribe method MS NETGrid OGSIUserManual v2 0 28 ofNotificationSourcePortType in the following manner public class MyNotificationSourceService PersistentGridServiceSkeletonInstanceAspProxy WebMethod public subscribeResponse subscribe XmlElement subscriptionExpression LocatorType sink TerminationTimeType expirationTime FaultType fault null subscribeResponse response object args new object subscriptionExpression sink expirationTime fault response subscribeResponse CallMethodOnPortType Ogsi Core Notification NotificationSourcePortType Subscribe args CheckFault fault return response You must alert the MS NETGrid OGSI container when you have changed service data values This can be performed via the NotifyChanged method on the Ogsi ServiceData ServiceData class An example of this is ServiceData someServiceDataElement InstanceServiceDataSet new XmlQualifiedName myServiceDataElement http someNameSpace com SomeServiceDataElement Value newValue So
8. ame MyService asmx serviceClass MyGridServices MyServiceImpl assembly MyServices persistence persistent gt lt gridServiceDeploymentDescriptor gt This entry specifies o The name of the asmx file generated in section 5 4 for example MyService asmx o The full name of the service class created in section 5 1 for example MyGridServices MyServiceImpl o The name of the assembly created in section 5 3 for example MyServices o Whether the service is persistent or transient 5 6 Installing the service To install the service o Copy the MyServices d11 assembly to lt OGSIContainer gt bin MS NETGrid OGSIUserManual v2 0 11 o Copy the MyService asmx file to lt oGSTContainer gt services persistent o Restart IIS To restart IIS obtain the control panel select Administrative Tools and then select Internet Services Manager Select the appropriate web site probably Default Web Site and use the stop and start icons to stop and restart the server MS NETGrid OGSIUserManual v2 0 12 6 Writing a client of a persistent service Writing a client to talk to a persistent Grid Service is identical to writing a client to talk to a Web Service Firstly we must create a proxy class for the service and then use it in our own code To create a proxy class create a new directory and within that directory use the following command line instruction WSDL http localhost Ogsi Container
9. ample class MyCallbackClass IServiceDataValuesCallback public object ServiceDataValues get code to create an object array of values goes her return result To specify that the callback mechanism should be used to determine the service data values the Callback property of the ServiceData class must be set to the instance of the callback class For example MyCallbackClass callbackInstance new MyCallbackClass sd Callback callbackiInstance It is important to note that this mechanism for dynamic service data value creation can only be used when the service data element is non modifiable 9 3 4 Lifetime attributes Service data values can have lifetime attributes associated with them To add a service data value with specific lifetime values to a ServiceData object the overloaded AddValue method can be used There is a version of the method that takes lifetime values as well as the value object itself For example Create value object MyClass myObject new MyClass Create lifetime objects System DateTime goodFrom System DateTime Now MS NETGrid OGSIUserManual v2 0 24 System DateTime goodUntil Ogsi Core Util GridDateTime INFINITY System DateTime availableUntil Ogsi Core Util GridDateTime INFINITY sd AddValue myObject goodFrom goodUntil availableUntil If no lifetime values are spe
10. an be used See the StockValueService demonstrator for details 11 1 Making a service data element notifiable You may wish only to expose certain service data elements in your service available for notification subscriptions The Ogsi ServiceData ServiceData class has a property called IsNotifiable for this purpose The default value of this property is false An example of use Construct a qualified name for the service data element System Xml XmlQualifiedName sdeName new System Xml XmlQualifiedName mySdeName MySdeNamespace Create a new service data element ServiceData sde sde serviceDataSet Create sdeName sde IsNotifiable true When the IsNotifiable property is set to true e Clients may subscribe for notifications to changes in the value s of this service data element e The service data elements will appear in the values of the ogsi notifiableServiceDataName service data element on the NotificationSourcePortType of the service 11 2 Creating a Source Service A Grid service can act as a source of notification messages by using the Ogsi Core Notification NotificationSourcePortType class via the OgsiPortTypeAttribute as described above This means that any notifiable service data in the sense explained in Section 10 1 above in the service data set of this service may be subscribed to for changes in their values An example of the use of Notification
11. anual is aimed at the Grid service developers and describes how to use the MS NETGrid implementation to create Grid services Details of how to write clients that use these services in the form of running examples are also included This document complements MS NETGridOgsiDesignOverview that is included with this distribution 1 1 Product Licence The MS NETGrid software is released under the licence described in LICENSE TXT under the root directory of the distribution 1 2 Project WWW Site The MS NETGrid Project WWW site is at http www epcc ed ac uk ogsanet 1 3 Support and Queries Please note that our software is intended as a proof of concept to demonstrate the applicability of Microsoft NET in general and ASP NET in particular to the development of Grid services rather than as a fully functioning product In consequence we do not provide any support for our software However please feel free to forward any comments queries suggestions or problems you have to ogsanet queries epcc ed ac uk MS NETGrid OGSIUserManual v2 0 5 2 Installation The download consists of a zip file called MS NETGridOGSI TP1 0 zip Extract this to a convenient directory of your choice At this location there will be a directory called MS NetGrid This directory will have a number of subdirectories one of which is called Ogsi Container This Ogsi Container directory contains the ASP NET based OGSI container as well as all source cod
12. cations ASP NET The NET version of ASP with extensions for Web Services and Enterprise Applications C Pronounced C Sharp a new Microsoft programming language that takes advantage of NET platform features Assembly A collection of managed code which may form an executable or a library and may be distributed across a number of physical files Assemblies facilitate the separation of logical and physical resources OGSA The Open Grid Services Architecture which is a set of proposed architectures and protocols for Grid computing Anatomy OGSI The Open Grid Services Infrastructure a specification of behaviours and properties of Grid Services Physiology OGSI Spec OGSA DAI OGSA Data Access and Integration Grid Services framework for seamless access and integration of data using the OGSA paradigm OGSA DAI MS NETGrid OGSIUserManual v2 0 33 Globus The Globus toolkit A standard toolkit of Grid software Version 3 will contain an implementation of OGSI in Java http www globus org WSDL The Web Services Description Language http ww w w3 org TR wsdl Web Services Refers to network enabled software capabilities accessed using common Internet protocols such as HTTP and SOAP and described using WSDL Grid Services Web Services conforming to the OGSI specification Grid Service Instance A network accessible instance of an OGSI compliant service PortType A set of ope
13. cified the goodFrom attribute defaults to the current time and the goodUntil and availableUntil attributes default to INFINITY It is possible to obtain the lifetime attributes associated with the values of a ServiceData object using the GetLifetimes method This method returns an array of ServiceDataAttributes objects each corresponding to a service data value The ServiceDataAttributes class has properties to get and set the lifetime attributes and also get and set the value to which the lifetime attributes are associated See the class documentation for classes ServiceData and ServiceDataAttributes for more details 9 3 5 Service data evaluators The grid service findServiceData and setServiceData operations are implemented by the GridServiceSkelton base class By default the findServiceData operation supports the queryByServiceDataNames query expression and the setServiceData operation supports the setByServiceDataNames and deleteByServiceDataNames query expressions It is possible to add new query expressions to these operations To add support for a new query expression you must implement a new query evaluator to evaluate the query Query evaluators must implement the IExpressionEvaluator interface The evaluator must then be added to the query engine The GridServiceSkeleton base class has a protected member variable queryEngine of type Ogsi ServiceData Query QueryEngine This class has a method RegisterEvaluator that can be used to a
14. class is for a persistent service so it inherits from Ogsi Core PersistentGridServiceSkeleton The service is to be a factory so the we have used the OgsiPortType attribute to specify that the service supports the Factory portType When we use the OgsiPortType attribute to specify that a service supports the Factory portType the majority of the implementation is done for us all we have to do is write a creator class to create instances of the service the factory creates and then specify that the creator class is associated with the factory These tasks are covered in sections 7 3 and 7 7 respectively The second and third arguments to the OgsiPortType attribute specify the namespace and name of the portType These values are not used in the current release but are intended to provide a reference to the portType for use in future releases 7 3 Write factory creator class The factory creator class is used to create instances of transient services The code which MS NETGrid OGSIUserManual v2 0 15 should be saved in a file called MyTransServiceFactoryCreator cs is using System using System Xml using Ogsi Core namespace MyGridServices public class MyTransServiceFactoryCreator IFactoryCreator public GridServiceSkeleton CreateServiceObject XmlElement creationParams IServiceParameters factory MyTransServiceImpl retval string greeting hello creat
15. dd a query evaluator to the query engine For examples of query evaluators see the implementations of QueryByServiceDataNamesEvaluator and SetByServiceDataNamesEvaluator both in the Ogsi ServiceData Query namespace MS NETGrid OGSIUserManual v2 0 25 10 PortTypes A large portion of OGSI Spec addresses the issue of services providing multiple portTypes and allowing services to inherit from multiple portTypes In our approach the WebMethodAttribiute marked methods in the proxy classes essentially represent the most derived portType for a service and it is with this that the clients communicate At present it is only possible to present this most derived portType to the client It is possible to alter the properties and namespaces of the exposed operations by using the WebServiceAttribute SoapDocumentMethodAttribute and SoapRpcMethodAttribute classes and others provided by the NET framework See the NET user documentation for details We address the issue of portType re use in the following manner When developing a service implementation service methods may be placed on the class you derive from GridServiceSkeleton like so public class MyService PersistentGridServiceSkeleton public string myMethod this InstanceServiceDataSet someQName 10 return hello With this method access to the service s ServiceDataSet is via the InstanceServiceData property inherited f
16. e for the container The Ogsi Container directory must be set up as a virtual directory under Internet Information Services IIS This can be done using Microsoft s Internet Services Manager see the user documentation for this product for details of creating a virtual directory Call the virtual directory ogsa Throughout the rest of this document the notation oGSIContainer refers to the full path name of the Ogsi Container directory e g C MS NETGrid Ogsi Container install dir refers to the directory into which the MS NETGrid directory was unzipped e g C N MS NETGrid OGSIUserManual v2 0 6 3 Running a Demonstration Client The installation 1s configured to initialise a counter service factory that can be used in conjunction with a supplied client to test your installation The client is located in install dir MS NETGrid CounterClient Go to the bin subdirectory and run the CounterClient executable Click on the Create New Counter button This creates a new instance of a transient counter service The Grid Service Handle for this service instance should appear in the Created counter handle box If it does not please make sure that IIS is running and the Ogsi Container directory is visible from Internet Services Manager Several operations may be performed on this service instance The count value may be set using the Set count value button This sets the current value of the counter to be that of the box
17. ee ee ette eee nest en eset ta sets esten osea se tou 6 4 Class documentation eerie eee esee eese en stent tn atn setas to setas stans sens etis etes stesse es seen seta seta setae 7 5 Writing a simple persistent service eeeeee ecce eese eren ee eren eene eren setas tasse ense ease tnu 8 5 1 Write the service class eeeeeeee esee eese esee enses tenetis tnn sente osea stesse esatta seta seta setae 8 5 Write the proxy class cesse eeee eere serene eee enne n eee oksene soos usop setas seta se tone seta sese ense to naue 9 5 3 Compile the service class and proxy class into an assembly 9 5 4 Write a asmx file for the service eerie eee eee eee eene entente ett etes stas ts sns 10 5 5 Configure the OGSI container 4 eres ee eee eren eese enero netta stone setas seen se tnon 10 5 6 Installing the service eese eee eere e eee en eerte neenon netta setas ast tn sse ta sete ss seen sese en se tnn 10 6 Writing a client of a persistent service 4 eese eese e cessere ee eren eerte neta neenon seen 12 7 Writing a transient service and a persistent Factory service eere 13 7 1 Write the transient service class eeeeee eee eee esee eee eene tenentes ttt s etse esses sn 13 7 2 Write the persistent factory service class eee ecce e eres eren ee eene enne etna tnu 14 7 3 W
18. ent is finished with it by calling the destroy method Compile this file along with MyTransService cs and MyTransServiceFactory cs as shown in the following command line csc out MyTransClient exe MyTransClient cs MyTransService cs MyTransServiceFactory cs This will produce an executable called MyTransClient exe that will use the factory to create a new instance of the transient Grid service and then call that service s he11o method several times to producing the output shown below Have a service the locator is http localhost Ogsi Container services transient MyTransService asmx instanceId instance 141776660 214136689 104091352482151152689462196422965 123173137 Ciao Mike 1 Ciao Daragh 2 Ciao Ally 3 MS NETGrid OGSIUserManual v2 0 21 9 Service data The concept of service data is an important part of OGSI The GridServiceSkeleton base class provides a collection for service data via the InstanceServiceData property Through this collection the service developer can manipulate the service data in many ways This section describes how the developer can manipulate the service data 9 1 Default service data elements All services will have several service data elements by default These are defined by the OGSI specification and are implemented in the GridServiceSkeleton base class The default service data elements are o interface o factoryLocator o gridServiceHandle o gridServiceRef
19. ent service The proxy code for these services is located in Ogsi Container services persistent and Ogsi Container services transient These services do not expose any additional functionality but do demonstrate the programming model that this document describes The counter subdirectory contains a more interesting example The transient service located in CounterServiceSimple cs exposes all the functionality of the GridService portType inherited from GridServiceSkeleton In addition Increment and Decrement methods are provided A serviceData element called count is defined with its own namespace The Increment and Decrement methods are used to alter the value of this serviceData element In addition the value of count may be set using the setServiceData operation provided by the GridService portType The deployment for the transient counter service and the persistent counter factory service may be examined in install dir MS NETGrid Ogsi Container Web config The counter factory demonstrates the use of previously existing portTypes via the OgsiPortTypeAttribute attribute The CounterFactoryCreator class demonstrates the use of the ITFactoryProvider interface The CreateServiceObject method takes an XML element with that specifies the initial value of the counter The notification demonstrator service has already been mentioned in Section 11 above MS NETGrid OGSIUserManual v2 0 32 13 Glossary For convenience of ref
20. erence o findServiceDataExtensibility o SsetServiceDataExtensibility o terminationTime o serviceDataName Other OGSI portTypes define a number of other default service data elements 9 2 Service data set The GridServiceSkeleton base class provides a protected member variable through which service implementations can access the service data collection This member variable is called serviceDataSet and is of type ServiceDataSet There is also a property called InstanceServiceDataSet for use by clients of the GridServiceSkeleton object The service data set is a container for service data elements Each service data element is referenced by an XML qualified name consisting of a local name and a namespace The ServiceDataSet class provides methods to create new service data elements add service data elements to the collection access service data elements from the collection as well as several others See the class documentation for full details of the class New service data elements can be added to the collection with code similar to the following Construct a qualified name for the service data element System Xml XmlQualifiedName sdeName new System Xml XmlQualifiedName mySdeName MySdeNamespace Create a new service data element ServiceData sde sde serviceDataSet Create sdeName MS NETGrid OGSIUserManual v2 0 22 code to populate the ServiceData object
21. erence we include the following glossary NET The Microsoft NET platform including the INET SDK Software Development Kit associated development tools such as Visual Studio NET http www microsoft com net and the Common Language Runtime Common Language Runtime a runtime environment that executes Microsoft Intermediate Language MSIL MSIL The NET bytecode a low level assembler like language executed by the Common Language Runtime Managed code Code that runs on the NET CLR IIS Microsoft Internet Information Server a web server offering communication over a variety of internet protocols ISAPI An Application Programming Interface API that allows applications to use the network services provided by IIS Commonly used to provide HTTP filters that respond to all HTTP requests on the server AppDomain NET allows the partitioning of a single Operating System process into a number of AppDomains which are essentially memory safe areas within the process If the code in an AppDomain crashes other AppDomains within the process are unaffected This concept has some performance advantages as using AppDomains avoids the overheads associated with starting a new process NET Remoting The mechanism by which NET allows Remote Procedure Call RPC between AppDomains and between remote machines ASP Active Server Pages a Microsoft technology that works in conjunction with IIS to host Web Appli
22. ethods e g findServiceData and destroy that correspond to the GridService portType operations that all Grid services must provide 5 1 Write the service class The service class is the class that implements the specific functionality of the Grid service The code for this class is as follows and should be saved in a file called MyServiceImpl cs using Ogsi Core namespace MyGridServices public class MyServicelmpl PersistentGridServiceSkeleton private int count_ 1 public string hello string name return hello name count_ ToString This class inherits from the Ogsi Core PersistentGridServiceSkeleton class All persistent Grid services must inherit from this class In contrast transient Grid services must inherit from the Ogsi Core GridServiceSkeleton class As can be seen from the code implementing the service class for a Grid service is very similar to writing any other class The Ogsi Core PersistentGridServiceSkeleton MS NETGrid OGSIUserManual v2 0 9 and Ogsi Core GridServiceSkeleton classes give access to other Grid service infrastructure such as service data that the service may wish to use This simple example does not use service data 5 2 Write the proxy class The proxy class is used to expose the service s public methods or in other words the operations of the Grid service to clients using standard Web service protocols The code f
23. file called MyTransService cs ls using System Web Services using Ogsi Container Instances Proxy namespace MyGridServices public class MyTransService TransientGridServiceInstanceAspProxy WebMethod public string hello string name object args name return string CallMethod hello args This class is virtually identical to the proxy class for the persistent service discussed in section 5 2 The only difference here is that this class inherits from TransientGridServiceInstanceAspProxy because it is a transient rather than persistent service The code for the factory class s proxy class which should be saved in a file called MyTransServiceFactory cs Is using System Web Services using Ogsi Container Instances Proxy using Ogsi Core Types namespace MyGridServices public class MyTransServiceFactory PersistentGridServiceInstanceAspProxy WebMethod public LocatorType createService CreationType creation object arguments creation return LocatorType CallMethodOnProvider Ogsi Core FactoryPortType CreateService arguments This class uses the CallMethodOnProvider method rather than the CallMethod method In this case Cal 1MethodOnProvider is used as the CreateService method is not defined MS NETGrid OGSIUserManual v2 0 17 directly on MyTransServiceFactoryImpl but on the Fact
24. goes here Add service data element to the service data set serviceDataSet Add sde The indexer property of the ServiceDataSet can be used to access the ServiceData objects by the service data element s qualified name as show here o Construct the qualified name for the service data element System Xm1l QualifiedName terminationTimeQName terminationTimeQName new System Xm1l QualifiedName terminationTime CoreConstants OGSI NAMESPACE URI Obtain the ServiceData object using the indexer ServiceData sd serviceDataSet terminationTimeQName can now use sd to access and alter the termination time service data element 9 3 The ServiceData class The ServiceData object is used to store the properties and values of the service data elements For full details of the ServiceData class see the class documentation this section provides an introduction to some of the mean features of the class 9 3 1 Service data element properties There are a number of standard OGSI properties that are associated with a service data element These are listed below along with their default values and corresponding property of the ServiceData class OGSI property Default value DataService property Minimum occurs inOccurs Maximum occurs axOccurs Mutability static utability Modifiable false odifiable Nillable false nillable 9 3 2 Service data value
25. iceImpl cs is as follows using Ogsi Core namespace MyGridServices public class MyTransServiceImpl GridServiceSkeleton private int count _ oh private string greeting public MyTransServicelmpl string greeting greeting greeting MS NETGrid OGSIUserManual v2 0 14 public string hello string name return greeting name count_ ToString This class inherits from the Ogsi Core GridServiceSkeleton class All transient Grid services must inherit from this class The most interesting feature of this class is that the constructor takes an argument We therefore require a mechanism to allow the client to pass this parameter to the factory that will create the service instances This mechanism will be explained in more detail in section 7 3 7 2 Write the persistent factory service class The factory service class is the class that implements the functionality of the persistent factory service The code which should be saved in a file called MyTransServiceFactoryImpl cs is as follows using System using Ogsi Core namespace MyGridServices OgsiPortType typeof FactoryPortType http localhost MyTransServiceFactoryNs MyTransServiceFactoryPortType public class MyTransServiceFactoryImpl PersistentGridServiceSkeleton As can be seen this is a very simple class The
26. ices and then use them in our own code To create proxy classes create a new directory and within that directory issue the following command line commands each should be entered on a single line WSDL namespace MyTransServiceNS http localhost Ogsi Container services transient MyTransService asmx WSDL namespace MyTransServiceFactoryNS http localhost Ogsi Container services persistent MyTransServiceFactory asmx This will create proxy classes called MyTransService cs and MyTransServiceFactory cs each within their own namespace to avoid name clashes with common types We can now write a client that uses the factory and the service instances it creates The code for the client is save this in a file called MyTransClient cs using System using System Xml using MyTransServiceNS using MyTransServiceFactoryNS class MyTransClient static void Main Create a factory service object MyTransServiceFactory factoryService new MyTransServiceFactory Construct XML creation element this is used to create the service instance XmlDocument doc new XmlDocument XmlElement xmlParams doc CreateElement initialValue XmlNode val doc CreateTextNode Ciao xmlParams AppendChild val Construct a creation object MyTransServiceFactoryNS CreationType creation creation new CreationType creation terminationTimeSpecified false creation serviceParameters
27. ionParams is an XmlElement containing parameters to be used in the creation of the new service instance if creationParams null if creationParams Name initialValue throw new ArgumentException creationParams should be of type initialValue greeting creationParams ChildNodes 0 Value Create a new service instance retval new MyTransServiceImpl greeting Return the new service instance return retval The factory creator class must implement the IFactoryCreator interface This interface has only one method called CreateServiceObject Essentially all this method has to do is create an instance of the transient service and return it The creationParams parameter of the CreateServiceObject method can be used to pass an arbitrary XML element from the client to the factory This is an ideal mechanism to use when the service class constructor requires one or more arguments This is the case in the code above the majority of the code is responsible for extracting the value for the constructor s greeting argument from the XML element 7 4 Write proxy classes Proxy classes are required to expose the services public methods We have to write proxy MS NETGrid OGSIUserManual v2 0 16 classes for both the transient service and the factory service The code for the service class s proxy class which should be saved in a
28. l GT3 Globus Toolkit version 3 and OGSI Available at http www globus org ogsa Physiology The Physiology of the Grid Draft 2 9 I Foster C Kesselman J Nick S Tuecke Available at http www gridforum org org ogsa wg Anatomy The Anatomy of the Grid 7 Foster C Kesselman S Tuecke Available at http www gridforum org ogsa wg OGSA DAI Open Grid Service Architecture Database Access and Integration http www ogsadai org uk WSDL Spec Web Services Description Language 1 1 http www w3 org TR 2001 NOTE wsdl 20010315 AXIS The Apache Axis SOAP Engine http ws apache org axis
29. meServiceDataElement NotifyChanged Once NotifyChanged has been called the container automatically alerts all subscribed parties to the change in values 11 3 Creating a sink service We provide the abstract NotificationSinkPortType class with the MS NETGrid software Since the behaviour of notification sinks upon receiving notification messages is not defined by OGSI Spec you must inherit from this class and override the deliverNotification method to carry out application specific processing The intended recipient of a notification message must be able to listen for and process HTTP requests and the SOAP messages contained within them The NET framework generally relies on IIS for the processing of Web requests which means that should you wish an application other than a Web service to receive notification messages you would have to implement your own in process HTTP listener Indeed this is the approach taken by MS NETGrid OGSIUserManual v2 0 29 Virginia Impl We have not provided such a capability in our release 11 3 1 The debug notification service We provide as part of the distribution a Web service that will take notification messages and write them to a file This service is to be found under the Ogsi Container services debug directory The service also allows you to obtain the last message that it received via the GetLastMessage operation This service is used by the
30. nt specifies a parameter that is passed to the service In this case the parameter name is creationProvider The parameter value is the name of the factory creator class that this factory service must use to create service instances followed by a comma followed by the name of the assembly containing the class This lt serviceParameter gt element therefore associates the creator class with the service factory that uses it The final piece of configuration that must be carried out is to set the domain name that is used when creating transient services This is simply the domain name of the machine running IIS Edit the following line in the Web config file found in the configuration gridContainer config containerProperties section and set the value field to the appropriate domain name e g www epcc ed ac uk add key domain value localhost gt 7 8 Install the services To install the service o Copy the MyTransServices dll assembly to lt OGSIContainer gt bin o Copy the MyTransService asmx file to lt OGSIContainer gt services transient o Copy the MyTransServiceFactory asmx file to lt OGSIContainer gt services persistent o Restart IIS MS NETGrid OGSIUserManual v2 0 19 8 Writing a client of a transient service Writing a client to talk to a transient Grid Service is virtually identical to writing a client to talk to a Web Service Firstly we must create a proxy classes for the serv
31. or the proxy class which should be saved in a file called MyService cs is as follows using System Web Services using Ogsi Container Instances Proxy namespace MyGridServices public class MyService PersistentGridServiceInstanceAspProxy WebMethod public string hello string name object args name return string CallMethodOnPortType ContainerConstants GRID SERVICE PORT TYPE PROVIDER hello args Va This class inherits from the PersistentGridServiceInstanceAspProxy class in namespace Ogsi Container Instances Proxy The System Web Services WebMethodAttribute is used to tell ASP NET to expose this method as a public Web method of the service Other ASP NET method attributes may be used to provide further customisation See the ASP NET user documentation for details Every method that is to be exposed as part of the Grid service must have a corresponding method defined for it in the proxy class The methods in the proxy class are all very similar They simply put the arguments into an array and then pass these arguments and the method name to the Ca11Method method that is a public method of the base class 5 3 Compile the service class and proxy class into an assembly To compile the service class and proxy class into an assembly use the following command line instruction which should be typed on a single line csc t library out MyServices dll MySe
32. oryPortType provider object associated with MyTransServiceFactoryImpl using OgsiPortTypeAttribute The first argument to CallMethodOnProvider is the name of the object type and is used to select the appropriate provider The second argument is the name of the method to call and the third argument is the parameters to pass to the method 7 5 Compile classes into an assembly To compile all the classes into an assembly use the following command line this should be typed on a single line csc t library out MyTransServices dll MyTransService cs MyTransServiceFactory cs MyTransServiceFactoryCreator cs MyTransServiceFactoryImpl cs MyTransServicelImpl cs v lt OgsiContainer gt bin Ogsi Container dll Where lt OGSIContainer gt is the path to the OGSI container installation 7 6 Write asmx files for the transient service and factory service To utilise ASP NET to deploy our Grid service we must create a asmx file for the transient service and the factory service As in the case of the persistent service this simply maps the service name to the proxy class The asmx file for the transient service is save in file MyTransService asmx 8 WebService Class MyGridServices MyTransService gt The asmx file for the factory service is save in file MyTransServiceFactory asmx 8 WebService Class MyGridServices MyTransServiceFactory 7 7 Configure the OGSI container For each Grid service hosted by the
33. rations supported by a Web or Grid Service ServiceData An XML based mechanism that allows a client to query the state of a service instance in a flexible and extensible manner ServiceDataElement A particular element of serviceData identified by a name and a value Tomcat A container for Java based Web Applications http jakarta apache org AXIS A Web Application running under Tomcat which provides Web Services functionality http xml apache org Programming Model A set of procedures and APIs used to develop an application in a given domain MS NETGrid OGSIUserManual v2 0 34 References Documents referenced in the text and other related documents include the following MS NETGridOgsiDesignOverview MS NETGrid OGSI Implementation Design Overview MS NETGridOgsiDesignOverview v1 0 D Byrne EPCC June 16 2003 MS NETGrid Proj Def Project Definition for a Collaboration Between Microsoft and EPCC MS NetGrid ProjDef V2 0 M Jackson EPCC April 25 2003 OGSI Spec S Tuecke K Czajkowski I Foster J Frey S Graham C Kesselman T Maguire T Sandholm D Snelling P Vanderbilt Open Grid Services Infrastructure OGSI Version 1 0 June 27th 2003 http forge gridforum org projects ogsi wg Virginia Impl OGSLNET An OGSI compliant Hosting Container for the NET Framework Grid Computing Group University of Virginia WWW site http www cs virginia edu humphrey GCG ogsi net htm
34. rite factory creator class ueeeee eee esee e eese eese eene eerte seen esten sse ta soto sss e tnos etta se ton 14 7 4 Write proxy classes eere tree keen nera e YE eet nue ues EN Yee bae VER Eo vp o soosse sis 15 7 5 Compile classes into an assembly eeeee cesse etes seen eee en netta netos seen osea se tnn 17 7 6 Write asmx files for the transient service and factory service 17 7 7 Configure the OGSI container 4 cresce eese eene eee esee eines en ese tn sets esten seen se toun 17 7 8 Install the Services eerte terere eo rao enean a eo roa eee e eene eaa a eben ee ra Fea eaae ea tosteet isitoe 18 8 Writing a client of a transient service eere ceres eee e esee eene enne rennes etas seen seen 19 MS NETGrid OGSIUserManual v2 0 3 9 Service data eei ieeo teen eset eoe eope aepo eet Enea Do esos Pe esa sa Des ER eb GERE ERR Ub Fe ere UU ee UC Pape sabe oss sensn 21 9 1 Default service data elements eese eese eese eee seen en sets etta ta atentos etos etas s tn nsio 21 9 2 Service data set 21 9 3 TheServiceData Class s cnccciccissnisccrsscscccesessssnevcsscndecnivconenodscesscesscensnoddvebecesaceeeansts 22 9 3 1 Service data element properties esee cesse eese eene e ette eere neenon etta ae enu 22 9 3 2 Service data values eee eee eese eene eene eene tns ta stis ta seta seta
35. rom GridServiceSkeleton Adding methods in this manner essentially means adding methods to a base service portType In other circumstances it may be desirable to use functionality developed elsewhere to provide operations or to logically group related functionality into single portTypes which you then wish to aggregate on your service We provide means of doing this using the Ogsi Core OgsiPortTypeAttribute and Ogsi Core OperationProviderBase classes and the Ogsi Core IOperationProvider interface 10 1 OgsiPortTypeAttribute We use as an example a class SomeUsefulClass with a method SomeUsefulMethod It is desired to expose this method as an operation on your service The simplest way to do this is as follows OgsiPortType typeof MyAssembly SomeUsefulClass http mydomain com myNameSpace UsefulPortType public class MyService PersistentGridServiceSkeleton The first parameter in the attribute is the type of your provider class The second parameter is the URI of the namespace for this new portType The third parameter is the name of the portType The latter two parameters do not have an effect at the moment but are included for possible future work When the MyService class is instantiated by the container instances of every class defined MS NETGrid OGSIUserManual v2 0 26 by its OgsiPortTypeAttributes are created and associated with the service instance When developing proxy methods for pro
36. rviceImpl cs MyService cs r OGSIContainer NMbinNOgsi Container dll lt OGSIContainer gt is the path to the OGSI container installation If you are using the Microsoft Visual Studio development environment configure your project MS NETGrid OGSIUserManual v2 0 10 to output an assembly called MyServices dll You will have to add the following references to the project before building o xOGSIContainer NbinNOgsi Container dll o System Web Services dll Regardless of whether you have used Visual Studio or the command line you should now have created an assembly called MyServices dll located in the current directory You need to copy this dll to OGSIContainer bin 5 4 Write a asmx file for the service To utilise ASP NET to deploy our Grid service we must create a asmx file for the service This simply maps the service name to the proxy class The asmx file is save this in a file called MyService asmx 80 WebService Class MyGridServices MyService gt The name of the asmx file determines the Grid Service Handle GSH for the service 5 5 Configure the OGSI container For each Grid service hosted by the OGSI container an entry must be added to the container s Web config file this file is located at lt oGSTContainer gt Web config Inside the lt gridServiceDeployment gt element of the file add the following entry lt gridServiceDeploymentDescriptor asmxProxyFileN
37. s Service data elements can have zero or more values It is important to initialise a ServiceData object with details of the values that can be stored within it For example the following code configures a ServiceData object to store values of type MyClass Assume there is a ServiceData object called sd Specify that the ServiceData objects will store values of type MyClass MS NETGrid OGSIUserManual v2 0 23 sd ValuesType typeof MyClass Values can be added to the ServiceData using the Addvalue method For example MyClass myObject new MyClass sd AddValue myObject There are several other methods and properties defined on the ServiceData class to manipulate the values of a service data element See the class documentation for more details 9 3 3 Using a callback to determine service data values dynamically In some instances it is preferably to calculate the service data values dynamically as and when they are needed rather than storing a collection of values in the ServiceData object This can be easily done by providing a callback class that the ServiceData class will use to determine the service data values whenever they are requested The callback class must implement the IServiceDataValuesCallback interface This interface specifies a single read only property called ServiceDataValues that returns an array of objects that are the service data values For ex
38. s that implements the functionality of the transient service 2 Write the factory service class 3 Write the factory creator class that is used by the factory to create instances of the transient service 4 Write proxy classes for the service class and factory service class 5 Compile classes into an assembly 6 Write asmx files for the transient service and factory service 7 Configure the OGSI container 8 Install the services The transient Grid service we write here is very simple It is initialised with a single string argument called greeting provided to the factory service via the Factory portType CreateService operation that will create our transient Grid service and we will implement a single method called hello The method takes one argument called name and will return the string greeting name n where greeting is the value of the greeting argument the service was initialised with name is the value of the name argument of the he11o method and n is an integer that starts at 1 and increments every time the method is called The Grid service will inherit additional methods e g findServiceData and destroy that correspond to the GridService portType operations that all Grid services must provide 7 14 Write the transient service class The service class is the class that implements the specific functionality of the Grid service The code for this class which should be saved in a file called MyTransServ
39. se tasa tasto seta seen aan 22 9 3 3 Using a callback to determine service data values dynamically 23 9 3 4 Lifetime attributes eeeeeee ceres eee e essen eene enne rta netos esten ors ssoi ssorse siso os roS 23 9 3 5 Service data evaluators eres eee e esee eene eren eee tenete enata seta sese tn seen se tnun 24 10 PortI ypes rer LEE 25 10 1 OgsiPortTypeA ttribute eee ee eee eere eerte ee eene ene neto aseo ta setas toss seen setas to 25 11 NOtHICATIOM 2 27 11 1 Making a service data element notifiable eeeeeeeee eee eee eene tentent 27 11 2 Creating a Source Service 4 eee ee eee ee esee ee eene enne tastes setas sse tn seen case ta 27 11 3 Creating a SINK SETVICE mer 28 11 3 1 The debug notification service eee eee essere eee enne eren neenon etta seen nae 29 11 4 Writing clients of notification sources eese esee e eene e eee eerte eene een seen nae 29 12 Iber isasulme c M 31 13 e OET Sh m 32 ROPE ON COS osc iet steseseveettorstetek eese bot onse ee ene Oo oe IPS ee See PRO IR ETE FER SEN EY ME on ERES ER So soba oessa si oooi 34 MS NETGrid OGSIUserManual v2 0 4 1 Introduction MS NETGrid is an ASP NET based implementation of the Open Grid Services Infrastructure This user m
40. services persistent MyService asmx If you are accessing our container from a remote host then you can replace localhost with the name of the host upon which our container is running This will create a proxy class called MyService cs We can now write a client that uses the service Code for an example client of our service is using System class MyClient static void Main MyService GridService new MyService Console WriteLine GridService hello Horace Compile this file along with the MyService cs file as shown in the following command line instruction csc out MyClient exe MyClient cs MyService cs This will produce an executable called MyClient exe that will call the Grid service s hello method when it is run producing the output shown below C Projects ogsanet client gt MyClient hello Horace 1 C Projects ogsanet client gt MyClient hello Horace 2 C Projects ogsanet client gt MyClient hello Horace 3 MS NETGrid OGSIUserManual v2 0 13 7 Writing a transient service and a persistent Factory service In this section we go through the stages required to write and deploy a simple transient Grid service with a corresponding persistent factory service The factory service can be used to create instances of the transient Grid service The stages are 1 Write the transient service clas
41. to the left of this button The Increment and Decrement buttons may be used to adjust the value of the counter by the amount displayed in the box between the buttons The Find Service Data button can be used to obtain service data by name The count service data is found by default The ServiceData values are displayed in the bottom textbox If this client operates correctly the installation has been successful The correctly operating client looks like the following screenshot Counter iene LN Counter factory url http localhost gsi Container services persistent CounterS erviceSimpleF actory asmx Initial Value o Create New Counter Created counter handle http localhost D gsi Container services transient CounterS erviceS imple asms instancel d instance 1 285907 72 887167421 21971 28332502051 112421161697994160139 o Set count value Decrement fi Increment Destroy service instance Service data to find count gridS erviceH andle Find Service Data lt serviceD ataV alues mlns sdz http www w3 org 2001 XMLSchema xmlns xsi http wwwy w3 org 2001 MLS chema instance xmlinsz http www gridforum org namespaces 2003 03 0GS5I gt 1 count mlnsz http localhost CounterNS d2p1 goodFrom 2003 06 16T 09 44 47 2422 001ra d2p1 goodUntil infinity d2p1 availableUntil infinity xmlns d2p1 http www gridforum org namespaces 2003 03 0G51 gt 5 lt count
42. vider based methods the Ca11MethodOnProvider method of GridServiceInstanceAspProxy is used WebMethod public int SomeOtherUsefulMethod return CallMethodOnProvider MyAssembly SomeUsefulClass SomeUsefulMethod object null The provider classes can be given access to the ServiceDataSet of the service in the following manner If the provider classes are found to implement IOperationProvider the ServiceInstance property defined by this interface is initialised with a reference to the instance of MyService that it is associated during initialisation We provide a basic implementation of IOperationProvider called Ogsi Core OperationProviderBase for convenience The provider class may now access the service s ServiceDataSet by obtaining a reference from the reference it maintains to the service class public class SomeOtherUsefulClass OperationProviderBase public int SomeOtherUsefulMethod int i process this ServiceInstance InstanceServiceData someQName i return i MS NETGrid OGSIUserManual v2 0 27 11 Notification The OGSI specification defines behaviours that allow clients to subscribe to changes in the values of certain service data elements MS NETGrid OGSI implements this portion of the specification as of release 1 2 A demonstration project is contained with this distribution that shows how the notification functionality c
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