Sample Implementation of ICacheLoader with Distribution Hints

The following implementation of ICacheLoader compares the distribution hints and loads the respective data through querying. If the hint matches “Products”, LoadProductData() fetches all products fulfilling the querying criteria, which are then loaded into the cache through the node. Similar action is taken for Customer and Orders, where the respective data is fetched and loaded accordingly.

public class Loader : ICacheLoader
{
    int ItemsPerHint = 10000;
    private SqlConnection connection;
    string _hint = null;

    void ICacheLoader.Init(IDictionary parameters, string cacheId)
    {
        try
        {
            IDictionaryEnumerator ide = parameters.GetEnumerator();
            while (ide.MoveNext())
            {
                //get connection string
                if (ide.Key.ToString().Equals("connectionstring",
                StringComparison.OrdinalIgnoreCase))
                {
                    string connString = ide.Value.ToString();
                    connection = new SqlConnection(connString);
                    connection.Open();
                }

                //get distribution hints – distributionhint is a keyword
                if (ide.Key.ToString().Equals("distributionhint",
                StringComparison.OrdinalIgnoreCase))
                {
                    _hint = ide.Value.ToString();
                }
            }
        }
        catch{/*handle exception*/}
    }

    LoaderResult ICacheLoader.LoadNext(object index)
    {
        if (_hint != null)
            return LoadData(index);
        else
            return new LoaderResult();
    }

    protected LoaderResult LoadData(object index)
    {
        //compare hints and load respective data
        if (_hint == "Products")
            return LoadProductData(index);
        else if (_hint == "Customer")
            return LoadCustomerData(index);
        else if (_hint == "Order")
            return LoadOrderData(index);
        else
            return new LoaderResult();
    }

    protected LoaderResult LoadProductData(object index)
    {
        LoaderResult result = new LoaderResult();
        try
        {
            int lastIndex = 0;
            if (index != null)
            {
                lastIndex = (int)index;
            }
            //fetch specific data based on query
            SqlCommand command = new SqlCommand("SELECT * FROM Products  WHERE ProductID > " +                 
            lastIndex.ToString() + " AND ProductID< " + (lastIndex+10).ToString(), connString);

            SqlDataReader reader = command.ExecuteReader();

            int nextLimit = 50 + lastIndex;
            string key = "Product_"+ product.ProductID;

            while (reader.Read() && lastIndex < nextLimit && lastIndex < ItemsPerHint)
            {
                Product product = new Product();
                product.ProductName = reader["ProductName"].ToString();
                product.ProductID = Convert.ToInt32(reader["ProductID"]);

                ProviderCacheItem providerItem = new ProviderCacheItem(product);
                result.Data.Add(key, providerItem);

                lastIndex++;
            }
            if (lastIndex < ItemsPerHint)
            {
                result.UserContext = lastIndex;
                result.HasMoreData = true;
            }
        }
        catch{/*handle exception*/}
        return result;
    }

    protected LoaderResult LoadCustomerData(object index)
    {
        //perform operations
        return new LoaderResult();
    }

    protected LoaderResult LoadOrderData(object index)
    {
        //perform operations
        return new LoaderResult();
    }
  }
}

Sample Implementation of ICacheLoader with Distribution Hints

See Also