How to: Add and Remove Items from an Azure In-Role Cache

The following examples show the ways you can add and remove objects for the cache.

To add an object to cache

1. Make sure that the using statement (Imports in Visual Basic) is at the top of your application code to reference the Microsoft.ApplicationServer.Caching namespace.

2. Create a DataCacheFactory object that is accessible to all parts of the application that need a cache client. If possible, store and reuse the same DataCacheFactory object to conserve memory and optimize performance.

3. Use the DataCacheFactory object to create a DataCache object (also referred to as the cache client), or use the default DataCache constructor to create a cache client directly.

4. After you have the DataCache object, use the Add method, the Put method, or the Item property to add an object to the cache. In the following examples, the DataCache instance is named myCache.

Example

The following example demonstrates how you can use the Add method to add an object to cache. You will get an exception if an object has already been cached by the same key (the first parameter).

'add string object to cache with key "Key0"
myCache.Add("Key0", "object added with Key0")

//add string object to cache with key "Key0"
myCache.Add("Key0", "object added with Key0");

The following example uses the Put method to add an object to cache. If an object has already been cached by the same key, it will be replaced.

'add or replace string object in cache using key "Key0"
myCache.Put("Key0", "object replaced or added using Key0")

//add or replace string object in cache using key "Key0"
myCache.Put("Key0", "object replaced or added using Key0");

The following example uses the Item property that has array notation to add an item to the cache. If an object has already been cached by the same key, it will be replaced.

'add or replace object in cache using array notation
myCache("Key0") = "object replaced or added using Key0"

//add or replace object in cache using array notation
myCache["Key0"] = "object replaced or added using Key0";

To remove an object from the cache

• Make sure that the using statement (Imports in Visual Basic) is at the top of your application code to reference the Microsoft.ApplicationServer.Caching namespace.

• Create a DataCacheFactory object that is accessible to all parts of the application that need a cache client. If possible, store and reuse the same DataCacheFactory object to conserve memory and optimize performance.

• Use the DataCacheFactory object to create a DataCache object (also referred to as the cache client).

• After you have the DataCache object, use the Remove method or the Item property to remove an object from cache. In the following examples, the DataCache instance is named myCache.

Example

The following example uses the Remove method to remove an object from cache.

'remove object in cache using key "Key0"
myCache.Remove("Key0")

//remove object in cache using key "Key0"
myCache.Remove("Key0");

The following example uses the Item property that has array notation to remove an object from cache.

'remove object in cache using array notation
myCache("Key0") = Nothing

//remove object in cache using array notation
myCache["Key0"] = null;