Write-Through Provider Configuration and Implementation

Note

This feature is only available in NCache Enterprise Edition.

To use Write-through caching, you need to implement the IWriteThruProvider interface provided by NCache. NCache framework will use this custom implementation to write data on the back-end data source. Please refer to Configuring Write-through in Administrators' Guide for more details.

Note that if a read-through provider is specified in client.ncconf in the default-writethru-provider tag, and has also been specified through API, the provider in API will overwrite the one specified in client.ncconf.

Note

In NCache, write-through providers are configured on cache level i.e. for clustered caches all nodes will contain provider configurations and their deployed assemblies.

Important

For Java, before deploying your JAR files, you need to make sure that:

You have JDK 11 installed.
Your Environment Variable for Java is set.

Install the following NuGet package in your application.
- Alachisoft.NCache.SDK
To utilize the APIs, include the following namespaces in your application:
- Alachisoft.NCache.Runtime.DatasourceProviders
- Alachisoft.NCache.Runtime
This should be a class library project using Microsoft Visual Studio.
Make sure to Deploy WriteThrough Provider using NCache Web Manager.
For API details refer to:IWriteThruProvider, WriteToDataSource.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-client</artifactId>
    <version>5.2.0</version>
</dependency>

Import the following packages in your application:
- import com.alachisoft.ncache.client.*;
- import com.alachisoft.ncache.runtime.exceptions.*
- import com.alachisoft.ncache.runtime.datasourceprovider.*
The application must be connected to cache before performing the operation.
Cache must be running.
Make sure that the data being added is serializable.
Make sure to Deploy ReadThrough Provider using NCache Web Manager.
For API details refer to:WriteThruProvider, writeToDataSource.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Sample Implementation of IWriteThruProvider Interface

The following code sample provides sample implementation for IWriteThruProvider class which configures the Write-Thru provider for your cache. The WriteToDataSource methods contain logic to perform an actual write operation on a configured data source. Using this, you can write objects, bulk objects and data types from cache into the data source.

After implementing and deploying this provider, you can make direct calls to NCache for write operations on the data source. NCache will use the WriteToDataSource method in the specified data access class to write operations on data source.

.NET/.NET Core
Java

// Contains methods used to save/update an object to the master data source.
public class SampleWriteThruProviderr : IWriteThruProvider
{
    // Object used to communicate with the Data source.
    private SqlConnection _connection;

    // Perform tasks like allocating resources or acquiring connections
    public void Init(IDictionary parameters, string cacheId)
    {
        try
        {
            string connString = GetConnectionString(parameters);

            if (!string.IsNullOrEmpty(connString))
            {
                _connection = new SqlConnection(connString);
                _connection.Open();
            }
        }
        catch (Exception ex)
        {
            // Handle exception
        }
    }

    // Perform tasks associated with freeing, releasing, or resetting resources.
    public void Dispose()
    {
        if (_connection != null)
            _connection.Close();
    }

    //Responsible for write operations on data source
    public OperationResult WriteToDataSource(WriteOperation operation)
    {
        ProviderCacheItem cacheItem = operation.ProviderItem;
        Product product = cacheItem.GetValue<Product>();

        switch (operation.OperationType)
        {
            case WriteOperationType.Add:
            // Insert logic for any Add operation
            break;
            case WriteOperationType.Delete:
            // Insert logic for any Delete operation
            break;
            case WriteOperationType.Update:
            // Insert logic for any Update operation  
            break;
        }

        // Write Thru operation status can be set according to the result. 
        return new OperationResult(operation, OperationResult.Status.Success);
    }

    public ICollection<OperationResult> WriteToDataSource(ICollection<WriteOperation> operations)
    {
        var operationResult = new List<OperationResult>();

        foreach (WriteOperation operation in operations)
        {
            ProviderCacheItem cacheItem = operation.ProviderItem;
            Product product = cacheItem.GetValue<Product>();

            switch (operation.OperationType)
            {
                case WriteOperationType.Add:
                // Insert logic for any Add operation 
                break;
                case WriteOperationType.Delete:
                // Insert logic for any Delete operation 
                break;
                case WriteOperationType.Update:
                // Insert logic for any Update operation 
                break;
            }

            // Write Thru operation status can be set according to the result
            operationResult.Add(new OperationResult(operation, OperationResult.Status.Success));
        }
        return operationResult;
    }

    public ICollection<OperationResult> WriteToDataSource(ICollection<DataTypeWriteOperation> operations)
    {
        var operationResult = new List<OperationResult>();

        foreach (DataTypeWriteOperation operation in operations)
        {
            var list = new List<Product>();
            ProviderDataTypeItem<object> cacheItem = operation.ProviderItem;
            Product product = (Product)cacheItem.Data;

            switch (operation.OperationType)
            {
                case DatastructureOperationType.CreateDataType:
                    // Insert logic for creating a new List
                    IList myList = new List<Product>();
                    myList.Add(product.ProductID);
                break;

                case DatastructureOperationType.AddToDataType:
                    // Insert logic for any Add operation 
                    list.Add(product);
                break;

                case DatastructureOperationType.DeleteFromDataType:
                    // Insert logic for any Remove operation
                    list.Remove(product);
                break;

                case DatastructureOperationType.UpdateDataType:
                    // Insert logic for any Update operation 
                    list.Insert(0, product);
                break;
            }

            // Write Thru operation status can be set according to the result. 
            operationResult.Add(new OperationResult(operation, OperationResult.Status.Success));
        }

        return operationResult;
    }

    // Parameters specified in Manager are passed to this method
    // These parameters make the connection string
    private string GetConnectionString(IDictionary parameters)
    {
        string connectionString = string.Empty;

        string server = parameters["server"] as string, database = parameters["database"] as string;
        string userName = parameters["username"] as string, password = parameters["password"] as string;

        try
        {
            connectionString = string.IsNullOrEmpty(server) ? "" : "Server=" + server + ";";
            connectionString = string.IsNullOrEmpty(database) ? "" : "Database=" + database + ";";

            connectionString += "User ID=";
            connectionString += string.IsNullOrEmpty(userName) ? "" : userName;
            connectionString += ";";

            connectionString += "Password=";
            connectionString += string.IsNullOrEmpty(password) ? "" : password;
            connectionString += ";";
        }
        catch (Exception exp)
        {
            // Handle exception
        }

        return connectionString;
    }

    // Deploy this class on cache
}

public class SampleWriteThruProvider implements WriteThruProvider 
{
    private Connection _connection;

     public void init(Map<String,String> parameters, String cacheId){
        try
        {

            String connString = getConnectionString(parameters);

            if (connString.isEmpty())
            {
                _connection.prepareStatement(connString);
                _connection.beginRequest();
            }      
        }
        catch(Exception ex)
        {
            // Handle exception
        }
    }

    // Perform tasks associated with freeing, releasing, or resetting resources.
    public void close(){
        try
        {
            if (_connection != null)
                _connection.close();
        }
        catch(Exception ex)
        {
            // Handle exceptions
        }
    }

     //Responsible for write operations on data source
    public OperationResult writeToDataSource(WriteOperation operation){
        try 
        {
            String key = operation.getKey();

            ProviderCacheItem cacheItem = operation.getProviderCacheItem();
            Product product = cacheItem.getValue(Product.class);

            switch (operation.getOperationType())
            {
                case Add:
                    // Insert logic for any Add operation
                    break;
                case Delete:
                    // Insert logic for any Delete operation
                    break;
                case Update:
                    // Insert logic for any Update operation
                    break;
            }
        }
        catch(Exception ex)
        {
            // handle exceptions
        }
        // Write Thru operation status can be set according to the result. 
        return new OperationResult(operation,OperationResult.Status.Success);
    }

    public Collection<OperationResult> writeToDataSource(Collection<WriteOperation> collection) throws Exception 
    {
        List<OperationResult> operationResults = new ArrayList<OperationResult>();

        for (WriteOperation writeOperation: collection) 
        {
            String key = writeOperation.getKey();
            ProviderCacheItem cacheItem = writeOperation.getProviderCacheItem();
            Product product = cacheItem.getValue(Product.class);

            switch (writeOperation.getOperationType())
            {
                case Add:
                    // Insert logic for any Add operation
                    break;
                case Delete:
                    // Insert logic for any Delete operation
                    break;
                case Update:
                    // Insert logic for any Update operation
                    break;
            }
            // Write Thru operation status can be set according to the result. 
            operationResults.add(new OperationResult(writeOperation,OperationResult.Status.Success));
        }
        return operationResults;
    }

    public Collection<OperationResult> writeDataStructureToDataSource(Collection<DataStructureWriteOperation> operations)
    {
        var operationResult = new ArrayList<OperationResult>();
        try 
        {
            for (DataStructureWriteOperation operation : operations) 
            {
                var list = new ArrayList<Product>();
                ProviderDataStructureItem<Object> cacheItem = operation.getProviderItem();
                Product product = (Product) cacheItem.getData();

                switch (operation.getOperationType())
                {
                    case CreateDataType:
                        // Insert logic for creating a new List
                        List myList = new ArrayList<Product>();
                        myList.add(product.getProductID());
                        break;
                    case AddToDataType:
                        // Insert logic for any Add operation
                        list.add(product);
                        break;
                    case DeleteFromDataType:
                        // Insert logic for any Remove operation
                        list.remove(product);
                        break;
                    case UpdateDataType:
                        // Insert logic for any Update operation
                        list.set(0,product);
                        break;
                }
                // Write Thru operation status can be set according to the result.
                operationResult.add(new OperationResult(operation,OperationResult.Status.Success));
            }
        }
        catch(Exception ex)
        {
            // handle exceptions
        }
        return operationResult;
    }

    private String getConnectionString(Map parameters)
    {
        String connectionString = null;

        try 
        {
            String server = parameters.get("server").toString();
            String database = parameters.get("database").toString();
            String userName = parameters.get("username").toString();
            String password = parameters.get("password").toString();

            if (!server.isEmpty())
            {
                connectionString = "Server=" + server + ";";
            }
            else
            {
                // Server name is empty
            }
            if (!database.isEmpty())
            {
                connectionString = connectionString + "Database=" + database + ";";
            }
            else
            {
                // Database is empty
            }
            if (!userName.isEmpty())
            {
                connectionString = connectionString + "User ID=" + userName + ";";
            }
            else
            {
                connectionString = connectionString + "User ID=" + "" + ";";
            }
            if (!password.isEmpty())
            {
                connectionString = connectionString + "Password=" + password + ";";
            }
            else
            {
                connectionString = connectionString + "Password=" + "" + ";";
            }
        } 
        catch (Exception e) 
        {
            // handle exceptions
        }
        return connectionString;
    }
}

Additional Resources

NCache provides sample application for write-through on GitHub.

Write-Through Provider Configuration and Implementation

Note

Note

Important

Pre-Requisites

Sample Implementation of IWriteThruProvider Interface

Additional Resources

See Also