Add/Update Cache Data with Groups

Note

This feature is only available in NCache Enterprise Edition.

NCache allows the user to add an item in cache with a certain group. There can only be a single item associated with a single group. CacheItem is a custom class provided by NCache which can be used to add data to the cache. CacheItem also lets you set additional specifications associated with an object as property of Groups.

CacheItem is added in the cache using the Insert method is a recommended approach with group if no item already exists in the cache with the specified key.

Whereas the Add operation fails if the key already exists and an exception will be thrown.

Pre-Requisites

Install the following NuGet package in your application.
- Alachisoft.NCache.SDK
Include the following namespaces in your application:
- Alachisoft.NCache.Client
- Alachisoft.NCache.Runtime
- Alachisoft.NCache.Runtime.Exceptions
The application must be connected to cache before performing the operation.
Cache must be running.
Make sure that the data being added is serializable.
For API details refer to: ICache, CacheItem, Insert, property(setting group), GetCacheItem()
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.

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.runtime.exceptions.*;
- import com.alachisoft.ncache.client.*;
The application must be connected to cache before performing the operation.
Cache must be running.
Make sure that the data being added is serializable.
For API details refer to: Cache , CacheItem, insert, setGroup, getCacheItem()
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.

Include the following modules in your application:
- const ncache = require('ncache-client')
The application must be connected to cache before performing the operation.
Cache must be running.
For API details refer to: Cache, CacheItem, insert, setGroup, getCacheItem
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.

In the following example, data group is set by assigning it as a property of CacheItem containing the object customer. For Java, data group is assigned by using the setGroup property of the CacheItem.

try
{
    // Pre-condition: Cache is already connected

    // Get customer from database against given customer ID
    Customer customer = FetchCustomerFromDB("ALFKI");

    // Create a unique cache key for this customer.
    string key = $"Customers:{customer.CustomerID}";

    // Create a new CacheItem
    var cacheItem = new CacheItem(customer);

    // Specify the group
    cacheItem.Group = "Important Customers";

    // Add customer object to cache with group
    CacheItemVersion version = cache.Insert(key, cacheItem);

    // cacheItem is successfully added in the cache with group
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-condition: Cache is already connected

    // Get customer from database against given customer ID
    Customer customer = fetchCustomerFromDB("ALFKI");

    // Create a unique cache key for this customer
    String key = "Customer:" + customer.getCustomerID();

    // Create a new CacheItem
    CacheItem cacheItem = new CacheItem(customer);

    // Specify the group
    cacheItem.setGroup("ImportantCustomers");

    // Add customer object to cache with group
    CacheItemVersion version = cache.insert(key, cacheItem);

    // cacheItem is successfully added in the cache with group
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Get customer from database against given customer ID
    var customer = this.fetchCustomerFromDB("ALFKI");

    // Create a unique cache key for this customer.
    var key = "Customers:" + customer.getCustomerID();

    // Create a new CacheItem
    var cacheItem = new ncache.CacheItem(customer);

    // Specify the group
    cacheItem.setGroup("Important Customers");

    // Add customer object to cache with group
    var version = await this.cache.insert(key, cacheItem);

    // cacheItem is successfully added in the cache with group
}
catch(error)
{
    // Handle errors
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Update Group of a CacheItem

Data group of a CacheItem can also be updated. CacheItem is a custom class provided by NCache which can be used to add data to the cache. CacheItem also lets you set group as property of the CacheItem.

The following example updates group in a CacheItem.

try
{
    // Pre-condtion: CacheItem is added with the group

    // Retrieve the cacheItem from the cache
    string key = "ALFKI";
    var cacheItem = cache.GetCacheItem(key);

    // Set the group property of cache as null
    cacheItem.Group = null;

    // Re-insert the item in the cache after the removal of group
    cache.Insert(key, cacheItem);

    // Get cacheitem with the updated version
    cacheItem = cache.GetCacheItem(key);

    // Specify the new group to be updated
    cacheItem.Group = "US Customers";

    // Re-insert the cacheItem in the cache with updated groups
    cache.Insert(key, cacheItem);

    // CacheItem is successfully added in the cache with updated group
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures 
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-condtion: CacheItem is added with the group

    // Get customer from database against given customer ID
    Customer customer = fetchCustomerFromDB(1000);

    // Create a unique cache key for this customer.
    String key = "Customer:" + customer.getCustomerID();

    //Retrieve cache item from cache
    CacheItem cacheItem = cache.getCacheItem(key);

    // Specify the new group to be updated
    cacheItem.setGroup("US Customers");

    // Re-insert the cacheItem in the cache with updated groups
    cache.insert(key, cacheItem);

    // CacheItem is successfully added in the cache with updated group
}
catch (OperationFailedException ex)
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
}
catch (Exception ex)
{
    // Any generic exception like NullPointerException or IllegalArgumentException
}

// This is an async method
try
{
    // Pre-condtion: CacheItem is added with the group

    // Retrieve the cacheItem from the cache
    var key = "ALFKI";
    var cacheItem = this.cache.getCacheItem(key);

    // Re-insert the item in the cache after the removal of group
    await this.cache.insert(key, cacheItem);

    // Get cacheitem with the updated version
    cacheItem = this.cache.getCacheItem(key);

    // Specify the new group to be updated
    cacheItem.setGroup("US Customers");

    // Re-insert the cacheItem in the cache with updated groups
    await this.cache.insert(key, cacheItem);

    // CacheItem is successfully added in the cache with updated group
}
catch(error)
{
   // Handle errors
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Additional Resources

NCache provides sample application for Groups on GitHub.

Add/Update Cache Data with Groups

Note

Pre-Requisites

Update Group of a CacheItem

Additional Resources

See Also