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13.2. Using the Infinispan CDI Module
The Infinispan CDI module can be used for the following purposes:
- To configure and inject Infinispan caches into CDI Beans and Java EE components.
- To configure cache managers.
- To control storage and retrieval using CDI annotations.
13.2.1. Configure and Inject Infinispan Caches
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13.2.1.1. Inject an Infinispan Cache
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An Infinispan cache is one of the multiple components that can be injected into the project's CDI beans.
The following code snippet illustrates how to inject a cache instance into the CDI bean:
public class MyCDIBean {
@Inject
Cache<String, String> cache;
}
public class MyCDIBean {
@Inject
Cache<String, String> cache;
}13.2.1.2. Inject a Remote Infinispan Cache
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The code snippet to inject a normal cache is slightly modified to inject a remote Infinispan cache, as follows:
public class MyCDIBean {
@Inject
RemoteCache<String, String> remoteCache;
}
public class MyCDIBean {
@Inject
RemoteCache<String, String> remoteCache;
}13.2.1.3. Set the Injection's Target Cache
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The following are the three steps to set an injection's target cache:
- Create a qualifier annotation.
- Add a producer class.
- Inject the desired class.
13.2.1.3.1. Create a Qualifier Annotation
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To use CDI to return a specific cache, create custom cache qualifier annotations as follows:
Example 13.1. Custom Cache Qualifier
@javax.inject.Qualifier
@Target({ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface SmallCache {}
@javax.inject.Qualifier
@Target({ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface SmallCache {}
Use the created
@SmallCache qualifier to specify how to create specific caches.
13.2.1.3.2. Add a Producer Class
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The following code snippet illustrates how the
@SmallCache qualifier (created in the previous step) specifies a way to create a cache:
Example 13.2. Using the @SmallCache Qualifier
The elements in the code snippet are:
@ConfigureCachespecifies the name of the cache.@SmallCacheis the cache qualifier.
13.2.1.3.3. Inject the Desired Class
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Use the
@SmallCache qualifier and the new producer class to inject a specific cache into the CDI bean as follows:
public class MyCDIBean {
@Inject @SmallCache
Cache<String, String> mySmallCache;
}
public class MyCDIBean {
@Inject @SmallCache
Cache<String, String> mySmallCache;
}13.2.2. Configure Cache Managers with CDI
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A Red Hat JBoss Data Grid Cache Manager (both embedded and remote) can be configured using CDI. Whether configuring an embedded or remote cache manager, the first step is to specify a default configuration that is annotated to act as a producer.
13.2.2.1. Specify the Default Configuration
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Specify a method annotated as a producer for the Red Hat JBoss Data Grid configuration object to replace the default Infinispan Configuration. The following sample configuration illustrates this step:
Example 13.3. Specifying the Default Configuration
Note
CDI adds a
@Default qualifier if no other qualifiers are provided.
If a
@Produces annotation is placed in a method that returns a Configuration instance, the method is invoked when a Configuration object is required.
In the provided example configuration, the method creates a new Configuration object which is subsequently configured and returned.
Prerequisites
Creating Non Clustered Caches
After a producer method is annotated, this method will be called when creating an EmbeddedCacheManager, as follows:
Example 13.4. Create a Non Clustered Cache
The
@ApplicationScoped annotation specifies that the method is only called once.
Creating Clustered Caches
The following configuration can be used to create an EmbeddedCacheManager that can create clustered caches.
Example 13.5. Create Clustered Caches
Invoke the Method to Generate an EmbeddedCacheManager
The method annotated with @Produces in the non clustered method generates Configuration objects. The methods in the clustered cache example annonated with @Produces generate EmbeddedCacheManager objects.
Add an injection as follows in your CDI Bean to invoke the appropriate annotated method. This generates
EmbeddedCacheManager and injects it into the code at runtime.
Example 13.6. Generate an EmbeddedCacheManager
... @Inject EmbeddedCacheManager cacheManager; ...
...
@Inject
EmbeddedCacheManager cacheManager;
...13.2.2.3. Configure a Remote Cache Manager
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The
RemoteCacheManager is configured in a manner similar to EmbeddedCacheManagers, as follows:
Example 13.7. Configuring the Remote Cache Manager
A single class can be used to configure multiple cache managers and remote cache managers based on the created qualifiers. An example of this is as follows:
Example 13.8. Configure Multiple Cache Managers
13.2.3. Storage and Retrieval Using CDI Annotations
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13.2.3.1. Configure Cache Annotations
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Specific CDI annotations are accepted for the JCache (JSR-107) specification. All included annotations are located in the
javax.cache package.
The annotations intercept method calls on CDI beans and perform storage and retrieval tasks as a result of these interceptions.
13.2.3.2. Enable Cache Annotations
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Interceptors can be added to the CDI bean archive using the
beans.xml file. Adding the following code adds interceptors such as the CacheResultInterceptor, CachePutInterceptor, CacheRemoveEntryInterceptor and the CacheRemoveAllInterceptor:
Example 13.9. Adding Interceptors
Note
The listed interceptors must appear in the
beans.xml file for Red Hat JBoss Data Grid to use javax.cache annotations.
13.2.3.3. Caching the Result of a Method Invocation
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A common practice for time or resource intensive operations is to save the results in a cache for future access. The following code is an example of such an operation:
A common approach is to cache the results of this method call and to check the cache when the result is next required. The following is an example of a code snippet that looks up the result of such an operation in a cache. If the results are not found, the code snippet runs the
toCelsiusFormatted method again and stores the result in the cache.
In such cases, the Infinispan CDI module can be used to eliminate all the extra code in the related examples. Annotate the method with the
@CacheResult annotation instead, as follows:
Due to the annotation, Infinispan checks the cache and if the results are not found, it invokes the
toCelsiusFormatted() method call.
Note
The Infinispan CDI module allows checking the cache for saved results, but this approach should be carefully considered before application. If the results of the call should always be fresh data, or if the cache reading requires a remote network lookup or deserialization from a cache loader, checking the cache before call method invocation can be counter productive.
13.2.3.3.1. Specify the Cache Used
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Add the following optional attribute (
cacheName) to the @CacheResult annotation to specify the cache to check for results of the method call:
@CacheResult(cacheName = "mySpecialCache")
public String doSomething(String parameter) {
<!-- Additional configuration information here -->
}
@CacheResult(cacheName = "mySpecialCache")
public String doSomething(String parameter) {
<!-- Additional configuration information here -->
}13.2.3.3.2. Cache Keys for Cached Results
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As a default, the
@CacheResult annotation creates a key for the results fetched from a cache. The key consists of a combination of all parameters in the relevant method.
Create a custom key using the
@CacheKey annotation as follows:
Example 13.10. Create a Custom Key
In the specified example, only the values of
p1 and p2 are used to create the cache key. The value of dontCare is not used when determining the cache key.
13.2.3.3.3. Generate a Custom Key
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Generate a custom key as follows:
The listed method constructs a custom key. This key is passed as part of the value generated by the first parameter of the invocation context.
To specify the custom key generation scheme, add the optional parameter
cacheKeyGenerator to the @CacheResult annotation as follows:
@CacheResult(cacheKeyGenerator = MyCacheKeyGenerator.class)
public void doSomething(String p1, String p2) {
<!-- Additional configuration information here -->
}
@CacheResult(cacheKeyGenerator = MyCacheKeyGenerator.class)
public void doSomething(String p1, String p2) {
<!-- Additional configuration information here -->
}
Using the provided method,
p1 contains the custom key.
13.2.4. Cache Operations
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13.2.4.1. Update a Cache Entry
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When the method that contains the
@CachePut annotation is invoked, a parameter (normally passed to the method annotated with @CacheValue) is stored in the cache.
Example 13.11. Sample @CachePut Annotated Method
Further customization is possible using
cacheName and cacheKeyGenerator in the @CachePut method. Additionally, some parameters in the invoked method may be annotated with @CacheKey to control key generation.
13.2.4.2. Remove an Entry from the Cache
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The following is an example of a
@CacheRemoveEntry annotated method that is used to remove an entry from the cache:
Example 13.12. Removing an Entry from the Cache
The annotation accepts the optional
cacheName and cacheKeyGenerator attributes.
13.2.4.3. Clear the Cache
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Invoke the
@CacheRemoveAll method to clear all entries from the cache.
Example 13.13. Clear All Entries from the Cache with @CacheRemoveAll
import javax.cache.annotation.CacheResult
@CacheRemoveAll (cacheName = "statisticsCache")
public void resetStatistics() {
<!-- Additional configuration information here -->
}
import javax.cache.annotation.CacheResult
@CacheRemoveAll (cacheName = "statisticsCache")
public void resetStatistics() {
<!-- Additional configuration information here -->
}
As displayed in the example, this annotation accepts an optional
cacheName attribute.
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