Summary: This example demonstrates an SBA scenario of stock processing.
The example contains 3 processing units, a feeder, a processor, and a mirror service. This SBA application can easily scale using GigaSpaces Management tools.
OverviewThis example demonstrates the usage of the .NET Processing Unit Container persistent space using the nHibernate External Data Source implementation and a mirror service. ArchitectureThis example includes a module that is deployed to the grid, and a domain model that consists of Data objects. The XAP66:DataFeeder\ module runs within a Processing Unit and writes Data objects with raw data into the remote space. The space is actually embedded within the other Processing Unit, which runs the XAP66:DataProcessor\ module. The DataProcessor service takes the new Data objects, processes the raw data and writes them back to the space. The example solution is based on three projects:
Application Workflow
Data Domain ModelThe only object in our model is the Data object. [SpaceClass] public class Data { [..] /// <summary> /// Gets the data type, used as the routing index inside the cluster /// </summary> [SpaceRouting] public Nullable<int> Type { get { return _type; } set { _type = value; } } /// <summary> /// Gets the data info /// </summary> public string Info { get { return _info; } set { _info = value; } } /// <summary> /// Gets or sets the data processed state /// </summary> public bool Processed { get { return _processed; } set { _processed = value; } } [..] } Note the attributes that are used in this object:
Basically, every Data object is written to the space by the DataFeeder with the processed value set to false, which is later set to true by the DataProcessor. DataProcessor
Code
/// /// Process given data from cluster and write the processed data back to the cluster. /// This processing unit is also responsible for starting up the space it will process the /// data from. /// public class DataProcessor : IProcessingUnit { [..] /// ///Initializes the processing unit /// ///Cluster info related to this processing unit ///Gets custom properties related to the processing unit public void Init(ClusterInfo clusterInfo, IDictionarycustomProperties) { //Get the space name from the properties string spaceUrl; customProperties.TryGetValue(Consts.SpaceUrlProperty, out spaceUrl); if (String.IsNullOrEmpty(spaceUrl)) throw new ArgumentNullException("spaceUrl", "Custom Properties must contain a space name property (" + Consts.SpaceUrlProperty + ")"); //Gets the use transaction state from the custom properties string useTransactionStr; customProperties.TryGetValue(Consts.UseTransactionsProperty, out useTransactionStr); _useTransactions = (String.IsNullOrEmpty(useTransactionStr) ? false : bool.Parse(useTransactionStr)); //Starts the space as a part of the cluster, the DataProcessor takes data from its embedded space only SpaceConfig spaceConfig = new SpaceConfig(); spaceConfig.ClusterInfo = clusterInfo; ISpaceProxy clusterProxy = SpaceProxyProviderFactory.Instance.FindSpace(spaceUrl, spaceConfig); //Gets the direct proxy from the cluster proxy that will be used by this processing unit _proxy = clusterProxy.GetServerAdmin().GetDirectProxy(); } /// ///Starts the processing unit /// public void Start() { //Create template to look for data that needs to be processed Data template = new Data(); template.Processed = false; //Creates a ExampleProcessor instance ExampleProcessor myProcessor = new ExampleProcessor(); //Starts a polling container using the given template _pollingContainer = new ExamplePollingContainer(_proxy, template, _useTransactions, myProcessor.ProcessData); Console.Write("DataProcessor started, waiting for data that needs processing..."); } /// ///Stops the processing unit /// public void Stop() { //Dispose the container, this stops the container work and cleanup used resources if (_pollingContainer != null) { _pollingContainer.Dispose(); _pollingContainer = null; } } /// ///Destroys the processing unit, any allocated resources should be cleaned up in this method /// public void Destroy() { if (_pollingContainer != null) _pollingContainer.Dispose(); //This processing unit created the space, therefor it should also close it //by calling Shutdown on the server admin _proxy.GetServerAdmin().Shutdown(); //Dispose the space proxy. to clean up any used resources _proxy.Dispose(); } } Configuration /./dotnetProcessingUnitDataExample false The actual work is being done by the ExamplePollingContainer and the ExampleProcessor, the polling container is actually taking the unprocessed Data objects from the space and executes the On Init, the Processing Unit is starts the embedded space with the given ClusterInfo Another important thing to note is that the Processing Unit explicitly calls _proxy.GetServerAdmin().Shutdown(); on Destroy(), which shuts down the embedded space. Otherwise, the space remains active even when this Processing Unit is undeployed. ExampleProcessorThe example processor is the business logic behind the data processor, it contains the actual processing method that will be called by the polling container. /// <summary> /// This class contain the processing logic /// </summary> internal class ExampleProcessor { [..] /// <summary> /// Receives a data and process it /// </summary> /// <param name="data">Data received</param> /// <returns>Processed data</returns> public Data ProcessData(Data data) { Console.WriteLine("**** processing - Took element with info: " + data.Info); //Process data... Thread.Sleep(ProcessingTime); //Set data state to processed data.Processed = true; Console.WriteLine("**** processing - done"); return data; } } ExamplePollingContainerThe polling container is executing a polling routine and execute a process method on any polled object and writes back the result to the space. /// <summary> /// A method that gets a polled object, process it and returns the processing result as an object /// </summary> /// <typeparam name="T">Type of object to poll</typeparam> /// <typeparam name="P">Type of object returned by processing</typeparam> /// <param name="polledObject">The object that was polled</param> /// <returns>Object result of processing that will be written back to the space</returns> public delegate P Process<T, P>(T polledObject); /// <summary> /// Executes polling logic on a given space /// </summary> /// <typeparam name="T">Type of object to poll</typeparam> /// <typeparam name="P">Type of object returned by processing</typeparam> public class ExamplePollingContainer<T, P> : IDisposable { [..] public ExamplePollingContainer(ISpaceProxy proxy, object template, bool useTransaction, Process<T, P> processMethod) { //Initialize variables _proxy = proxy; _useTransaction = useTransaction; _processMethod = processMethod; _signalShouldWork = new ManualResetEvent(false); _isDisposed = false; //Create IPreparedTemplate from the given template _template = proxy.Snapshot(template); //Get current space mode _spaceMode = _proxy.GetServerAdmin().SpaceMode; //Register for space mode changed events that will start/stop the work according to the //space mode (Work only in primary) _proxy.GetServerAdmin().SpaceModeChanged += PollingContainer_SpaceModeChanged; //Creates a new thread for the polling action and start it _pollingThread = new Thread(new ThreadStart(DoPoll)); _pollingThread.Start(); } /// <summary> /// Switch working state according to the new space mode /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void PollingContainer_SpaceModeChanged(object sender, SpaceModeEventArgs e) { //Update the current space mode _spaceMode = e.Mode; //If it is primary, signal the polling thread to start working if (_spaceMode == SpaceMode.Primary) _signalShouldWork.Set(); //else signal it to stop working else _signalShouldWork.Reset(); } private void DoPoll() { //This method must be called on each new thread that is created, it is //used to set the context class loader on the JVM SpaceProxyProviderFactory.Instance.SetThreadContext(_proxy); while (!_isDisposed) { //Work only if the space is in primary mode if (_spaceMode == SpaceMode.Primary) { try { //Creates a local transaction if required ITransaction tx = _useTransaction ? _proxy.CreateLocalTransaction() : null; try { //Executes the actual poll by Take space operation T polledObject = _proxy.Take<T>(_template, tx, _timeout); if (polledObject != null) { //If an object was polled executes the process method on it P processedObject = _processMethod(polledObject); //If the process method returned a value, write it back to the space if (processedObject != null) _proxy.Write(processedObject); } //Executes transaction if needed if (tx != null) tx.Commit(); } catch { //Abort the transaction if an error happend if (tx != null) tx.Abort(); } } //In case space switched to backup mode inside the if block, an exception will be //thrown and we want to return to the loop and wait until the space returns //to primary mode or any other exception. catch (Exception ex) { Console.WriteLine(ex); } } else //Waits until the space returns to the primary mode WaitHandle.WaitAll(new WaitHandle[] { _signalShouldWork }); } } public void Dispose() { //Will stop the working thread _isDisposed = true; //Unregister from space mode changed events _proxy.GetServerAdmin().SpaceModeChanged -= PollingContainer_SpaceModeChanged; //Waits for the polling thread to stop with a timeout _pollingThread.Join(_timeout * 5); } } The polling container receives a proxy, template and a delegate to a Process method and executes a polling routine that attempts to take an object from the given proxy by the given template, if it succeed it executes the process method on it and writes back the result to the proxy. Since the polling container should only work on space which is in Primary mode, it first register to space mode changed events and will only work when the space is in Primary mode. DoPoll does the polling routine on a separate thread and includes a method call to SpaceProxyProviderFactory.Instance.SetThreadContext(_proxy). This method call must be executed on every new thread created in the Processing Unit that needs to perform operations on the space. To stop to polling the Dispose should be called. DataFeederThe data feeder is in charge of feeding the cluster with unprocessed data every second. It does so by creating new Data objects with a random type and random information, and writes it to the cluster.
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/// /// Data feeder feeds new data to the space that needs to be processed /// public class DataFeeder : IProcessingUnit { [..] /// /// Initializes the processing unit /// ///Cluster info related to this processing unit ///Gets custom properties related to the processing unit public void Init(ClusterInfo clusterInfo, IDictionarycustomProperties) { //Get the space name from the properties string spaceUrl; customProperties.TryGetValue(Consts.SpaceUrlProperty, out spaceUrl); if (String.IsNullOrEmpty(spaceUrl)) throw new ArgumentNullException("spaceUrl", "Custom Properties must contain a space name property (" + Consts.SpaceUrlProperty + ")"); //Get feed delay from the custom properties, if none found uses the default one string feedDelayStr; customProperties.TryGetValue(Consts.FeedDelayProperty, out feedDelayStr); _feedDelay = (String.IsNullOrEmpty(feedDelayStr) ? DefaultFeedDelay : int.Parse(feedDelayStr)); //Connects to the space _proxy = SpaceProxyProviderFactory.Instance.FindSpace(spaceUrl); } /// ///Starts the processing unit /// public void Start() { //Set the started state to true _started = true; //Create a working thread _feedingThread = new Thread(new ThreadStart(StartWorking)); //Starts the working thread _feedingThread.Start(); } /// ///Stops the processing unit /// public void Stop() { //Set the started state to false _started = false; } /// ///Destroys the processing unit, any allocated resources should be cleaned up in this method /// public void Destroy() { //Set the started state to false _started = false; //Wait for the working thread to finish its work _feedingThread.Join(_feedDelay * 5); //It is very important to dispose the space when done to clean up //any uses resources _proxy.Dispose(); } /// /// Generates and feeds data to the space /// private void StartWorking() { try { //This method must be called on each new thread that is created, it is //used to set the context class loader on the JVM SpaceProxyProviderFactory.Instance.SetThreadContext(_proxy); Random random = new Random(); while (_started) { //Create a new data object with random info and random type Data data = new Data(Guid.NewGuid().ToString(), random.Next(0, DataTypesCount)); Console.WriteLine("Added data object with info {0} and type {1}", data.Info, data.Type); //Feed the data into the cluster _proxy.Write(data); Thread.Sleep(_feedDelay); } } [..] } } Configuration jini://*/*/dotnetProcessingUnitDataExample The StartWorking() method does the actual work, by creating a new Data object with random data in an unprocessed state every second, and feeds it to the cluster. StartWorking includes a method call to SpaceProxyProviderFactory.Instance.SetThreadContext(_proxy) for the same reason described in the XAP66:DataProcessor\ section. Building the ExampleThis example includes two scripts, compile.bat and copydeploymentfiles.bat. these two files needs to be executed. From the <Example Root> directory (<GigaSpaces Root>\dotnet\examples\ProcessingUnit), call: compile This compiles all the related projects and creates the processing units dlls inside each project under Deployment\lib directory. Then the copydeploymentfiles.bat file should be executed. From the <Example Root> directory (<GigaSpaces Root>\dotnet\examples\ProcessingUnit), call: copydeploymentfiles This copies the Processing Units Deployment directory to the <GigaSpaces Root>\deploy directory which simplifies deployment through the gs-ui.
DeploymentThere are two ways to deploy the Processing Units: Standalone DeploymentOne option is to run a standalone Processing Unit container and deploy the Processing Unit into it. This is done simply by calling the following commands from your <GigaSpaces Root>\bin directory: The following deploys the data processor: puInstance ..\dotnet\examples\ProcessingUnit\Processor\Deployment The following deploys the data feeder: puInstance ..\dotnet\examples\ProcessingUnit\Feeder\Deployment Each command creates the standalone container and deploys the DataProcessor or DataFeeder Processing Units to it. Since the Processing Unit logic is defined in the Start method, it starts working immediately after it is deployed. Grid DeploymentUnder <GigaSpaces Root>\dotnet\examples\ProcessingUnit, you can find two directories: Feeder and Processor. These contain the two Processing Units projects, in each of this directory there's the Deployment directory. This directory is in the required structure to deploy a Processing Unit, and is copied by the copydeploymentfiles script to the <GigaSpaces Root>\deploy directory. This allows deployment to the Service Grid using the gs-ui. META-INF\spring is where pu.xml resides. This file defines exactly which Processing Unit to deploy. After you run the build script and the copy deployment files script, the two directories are copied to the <GigaSpaces Root>\deploy directory, start up the Service Grid. Because this example runs in a partitioned cluster with two primary spaces and one backup space for each partition; you need to run one Grid Service Manager (GSM) and two Grid Service Containers (GSC), and then start the GigaSpaces Management Center: Start <GigaSpaces Root>\bin\gsm Start <GigaSpaces Root>\bin\gsc Start <GigaSpaces Root>\bin\gsc Start <GigaSpaces Root>\bin\gs-ui For running the GSC in a 64-bit platform, follow instructions in: http://www.gigaspaces.com/wiki/display/XAP66/Running+Services+-+GSC+and+GSM#RunningServices-GSCandGSM-64bitConfiguration
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