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.

Pre-Requisites

To utilize the APIs, include the following namespace 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 ReadThrough Provider using NCache Web Manager.

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.

// 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;
    }

    // Paramters 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
}

Additional Resources

NCache provides sample application for write-through at:

GitHub
Shipped with NCache: %NCHOME%\samples\dotnet\BackingSource

Write-Through Provider Configuration and Implementation

Note

Note

Pre-Requisites

Sample Implementation of IWriteThruProvider Interface

Additional Resources

See Also