| < Previous page | Next page > |
Configuring Write-Through Provider
To use Write-through caching you need to implement IWriteThruProvider interface provided by NCache. NCache framework will use this custom implementation to write data on backend data source.
Implementing IWriteThru Provider Interface
To implement IWriteThruProvider, add following references in provider assembly.
Alachisoft.NCache.Runtime.dll.
Create a class that implements Alachisoft.NCache.Runtime.DatasourceProviders.
IWriteThruProvider interface and deploy it using NCache Manger. NCache framework will internally use this class to perform write operation on configured data source.
IWriteThru Interface
Sample Code for IWriteThruProvider
/// Contains methods used to save/update an object to the master data source.
public class SampleWriteThruProvider : 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)
{
object connStringObject = parameters["connstring"];
string connString = connStringObject == null ? "" : connStringObject.ToString();
if (connString != "")
_connection = new SqlConnection(connString);
try
{
_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)
{
Product product = (Product)operation.ProviderCacheItem.Value;
SqlCommand command = new SqlCommand();
command.Connection = _connection;
if (operation.OperationType == WriteOperationType.Add)
command.CommandText = "INSERT INTO Products(ID,Name)VALUES( '" + operation.Key + "','" + product.ProductName + "')";
if (operation.OperationType == WriteOperationType.Delete)
command.CommandText = "DELETE FROM Products WHERE ID ='" + operation.Key + "'";
if (operation.OperationType == WriteOperationType.Update)
command.CommandText = "UPDATE Products SET Name = '" + product.ProductName + "' WHERE ID='" + operation.Key + "'";
int result = command.ExecuteNonQuery();
OperationResult operationResult = new OperationResult(operation, OperationResult.Status.Success);
if (result < 1)
{
operationResult.DSOperationStatus = OperationResult.Status.Failure;
}
return operationResult;
}
public OperationResult[] WriteToDataSource(WriteOperation[] operations)
{
OperationResult[] operationResult = new OperationResult[operations.Length];
SqlCommand command = new SqlCommand();
command.Connection = _connection;
int counter = 0;
foreach (WriteOperation operation in operations)
{
Product product = (Product)operation.ProviderCacheItem.Value;
if (operation.OperationType == WriteOperationType.Add)
command.CommandText = "INSERT INTO Products(ID,Name)VALUES( '" + operation.Key + "','" + product.ProductName + "')";
if (operation.OperationType == WriteOperationType.Delete)
command.CommandText = "DELETE FROM Products WHERE ID ='" + operation.Key + "'";
if (operation.OperationType == WriteOperationType.Update)
command.CommandText = "UPDATE Products SET Name = '" + product.ProductName + "' WHERE ID='" + operation.Key + "'";
int result = command.ExecuteNonQuery();
operationResult[counter] = new OperationResult(operation, OperationResult.Status.Success);
if (result < 1)
{
operationResult[counter].DSOperationStatus = OperationResult.Status.Failure;
}
counter++;
}
return operationResult;
}
}
After implementing and deploying this provider, you can make direct calls to NCache for write operations on data source. NCache will use "WriteToDataSource" method in specified data access class to write operations on data source.
Using Write-Through with Basic Operations
This section will explain the use of write-through provider after configuring and deploying it. NCache supports multiple Write-Through providers with applications.
The following namespaces should be added in application:
using Alachisoft.NCache.Web.Caching;
using Alachisoft.NCache.Runtime.DatasourceProviders;
using Alachisoft.NCache.Runtime;
NCache provides Alachisoft.NCache.Web.Caching.DSWriteOption enum to specify Write thru/Write behind options in APIs. Multiple write-through providers can be configured through NCache. Default provider will be called if specific provider name is not mentioned through API. You can also use providers other than default by using provider specific overloads of APIs.
Product product = new Product();
product.ProductID = 1001;
product.ProductName = "Chai";
CacheItem cacheItem = new CacheItem(product);
string key = "Product:" + product.ProductID ;
try
{
CacheItemVersion itemVersion = cache.Add(key, cacheItem, DSWriteOption.WriteThru, null);
}
catch (OperationFailedException exp)
{
// handle exception
}
Product product = new Product();
product.ProductID = 1001;
product.ProductName = "Chai";
CacheItem cacheItem = new CacheItem(product);
string key = "Product:" +product.ProductID ;
CacheItemVersion updatedItemVersion;
try
{
updatedItemVersion = cache.Insert(key, cacheItem, DSWriteOption.WriteThru, "XmlWriteThruProvider", null);
if (updatedItemVersion.Version> 1)
{
//Item updated in cache. Perform further tasks.
}
}
catch (OperationFailedException exp)
{
//handle exception
}
string key = "Product:1001";
try
{
cache.Delete(key, DSWriteOption.WriteThru, null);
}
catch (OperationFailedException exp)
{
// handle exception
}
string key = "Product:1001";
Product product = null;
try
{
Object returnObject = cache.Remove(key, DSWriteOption.WriteThru, null);
//Verify the removed item from both cache and data source
if (returnObject != null)
{
product = (Product)returnObject;
}
}
catch (OperationFailedException exp)
{ // handle exception }
Product product = new Product();
product.ProductID = 1001;
product.ProductName = "Chai";
CacheItem cacheItem = new CacheItem(product);
string key = "Product:" + product.ProductID ;
try
{
cache.AddAsync(key, cacheItem, DSWriteOption.WriteThru, null);
}
catch (OperationFailedException exp)
{
//handle exception
}
i. Add without Callback Method
string key = "Customer:David:1001";
CacheItem cacheItem = new CacheItem(new Product());
try
{
cache.Add(key, cacheItem, DSWriteOption.WriteBehind, null);
}
catch (Exception exp)
{
//Operation fails if the item already exists
// Request is not sent to the backing source in
}
ii. Add with Callback Method
protected void OnDataSourceItemsAdded(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void AddTest()
{
string key = "Customer:David:1001";
CacheItem cacheItem = new CacheItem(new Product());
try
{
cache.Add(key, cacheItem, DSWriteOption.WriteBehind, OnDataSourceItemsAdded);
//Verify item added in cache and in main source
}
catch (Exception exp)
{
//Operation fails if the item already exists
}
}
protected void OnDataSourceItemsUpdated(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void UpdateTest()
{
string key = "Customer:David:1001";
cacheItem.SubGroup = "WriteThru-Test";
try
{
cache.Insert(key, cacheItem, DSWriteOption.WriteBehind,OnDataSourceItemsUpdated);
}
catch (Exception exp)
{
//handle exception
}
}
protected void OnDataSourceItemsRemoved(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void DeleteTest()
{
string key = "Customer:David:1001";
try
{
cache.Delete(key, DSWriteOption.WriteBehind, OnDataSourceItemsRemoved);
//Verify the removed item from both cache and data source
}
catch (OperationFailedException exp)
{
//Operation fails if key does not exist in the cache
}
}
i. Add New Item Asynchronously
protected void OnDataSourceItemsAdded(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void AsyncAddTest()
{
try
{
string key = "Customer:David:1001";
CacheItem cacheItem = new CacheItem(new Product());
cache.AddAsync(key, cacheItem, DSWriteOption.WriteBehind,OnDataSourceItemsAdded);
//verify that the key is added in Cache and master source
}
catch (Exception exp)
{
//handle exception
}
}
ii. Update Existing Item Asynchronously
protected void OnDataSourceItemsUpdated(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void AsyncUpdateTest()
{
Cache mycache = NCache.InitializeCache("myreplicatedcache");
try
{
string key = "Customer:David:1001";
CacheItem cacheItem = new CacheItem(new Product());
cacheItem.SubGroup = "Async-WriteThru-Test";
cache.InsertAsync(key, cacheItem, DSWriteOption.WriteBehind, OnDataSourceItemsUpdated);
//verify that the key is updated in Cache and master source
}
catch (Exception exp)
{
//handle exception
}
}
i. Add New Items Using AddBulk Call
protected void OnDataSourceItemsAdded(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void BulkAddTest()
{
try
{
String[] key = {"Customer:David:1001","Customer:Paul:1002","Customer:Dave:1003","Customer:Mathew:1004"};
//create custom objects of Product type
CacheItem[] data = GetCacheItems(keys.Length);
IDictionary failedItems = cache.AddBulk(keys, data, DSWriteOption.WriteBehind, OnDataSourceItemsAdded);
//verify updated items in the main source
}
catch (Exception exp)
{
//handle exception
}
}
ii. Update Existing Items Using InsertBulk API
protected void OnDataSourceItemsUpdated(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void BulkUpdateTest()
{
try
{
String[] key = {"Customer:David:1001","Customer:Paul:1002","Customer:Dave:1003","Customer:Mathew:1004"};
//create new custom objects for above mentioned keys of Product type
CacheItem[] data = cache.GetCacheItems(keys.Length);
IDictionary failedItems = cache.InsertBulk(keys, data, DSWriteOption.WriteBehind, OnDataSourceItemsUpdated);
//verify updated items in the main source
}
catch (Exception exp)
{
//handle exception
}
}
iii. Delete Existing Items Using DeleteBulk API
protected void OnDataSourceItemsRemoved(IDictionary iDict)
{
//Perform appropriate actions upon response
}
private void BulkDeleteTest()
{
try
{
String[] key = {"Customer:David:1001","Customer:Paul:1002","Customer:Dave:1003","Customer:Mathew:1004"};
IDictionary failedItems = cache.DeleteBulk(keys, DSWriteOption.WriteBehind, OnDataSourceItemsRemoved );
//verify items deleted from the main source
}
catch (Exception exp)
{
//handle exception
}
}
See Also
Data Source Providers Overview | Read-Through Caching | Write-Through Caching | Configuring Read-Through Provider | Configuring Data Source Providers | Dynamic Compact Serialization | WAN Replication Through Bridge | Custom Dependency | Client Side API Programming
|
