svn commit: r1618726 - /deltaspike/site/trunk/content/core.mdtext

[ra...@apache.org]

Author: rafabene
Date: Mon Aug 18 20:48:03 2014
New Revision: 1618726

URL: http://svn.apache.org/r1618726
Log:
DELTASPIKE-640 - give some hints how to implement custom scopes

Modified:
    deltaspike/site/trunk/content/core.mdtext

Modified: deltaspike/site/trunk/content/core.mdtext
URL: http://svn.apache.org/viewvc/deltaspike/site/trunk/content/core.mdtext?rev=1618726&r1=1618725&r2=1618726&view=diff
==============================================================================
--- deltaspike/site/trunk/content/core.mdtext (original)
+++ deltaspike/site/trunk/content/core.mdtext Mon Aug 18 20:48:03 2014
@@ -806,8 +806,7 @@ that exception chain, unless it's explic
 
 ## Scopes
 
-DeltaSpike Core provides the API and SPI for several scopes.
-Currently all scopes are only implemented in the JSF module.
+DeltaSpike Core provides the API and SPI for several scopes. Currently all scopes are only implemented in the [JSF module](jsf.html#scopes). 
 
 ### @WindowScoped
 
@@ -815,6 +814,74 @@ Currently all scopes are only implemente
 
 ### @GroupedConversationScoped
 
+## Creating a custom CDI Scope
+
+If you want to create a custom CDI scope to match your needs, you will need to follow these steps:
+
+1. First, create an Annotation with annotated with @javax.inject.Scope; Example:
+
+    :::java
+    @Scope
+    @Retention(RetentionPolicy.RUNTIME)
+    @Target({ElementType.TYPE,ElementType.METHOD,ElementType.FIELD})
+    public @interface ACustomScope {}
+    
+2. Second, create an Extension to add the scope and a context for it. Example:
+
+    :::java    
+    public class ACustomScopeExtension implements Extension, Serializable {
+	
+    	public void addACustomScope(@Observes final BeforeBeanDiscovery event) {
+    		event.addScope(ACustomScope.class, true, false);
+    	}
+
+    	public void registerACustomScopeContext(@Observes final AfterBeanDiscovery event) {
+    		event.addContext(new ACustomScopeContext());
+    	}
+    }
+
+3. Implement a javax.enterprise.context.spi.Context interface to hold the javax.enterprise.inject.spi.Bean instances according to your needs
+
+    :::java
+    public class ACustomScopeContext implements Context, Serializable {
+
+      // Get the scope type of the context object.
+    	public Class<? extends Annotation> getScope() {
+    		return ACustomScope.class;
+    	}
+
+    	// Return an existing instance of certain contextual type or create a new instance by calling
+    	// javax.enterprise.context.spi.Contextual.create(CreationalContext) and return the new instance.
+    	public <T> T get(Contextual<T> contextual, CreationalContext<T> creationalContext) {
+    		Bean bean = (Bean) contextual;
+    		// you can store the bean somewhere
+    		if (somewhere.containsKey(bean.getName())) {
+    			return (T) somewhere.get(bean.getName());
+    		} else {
+    			T t = (T) bean.create(creationalContext);
+    			somewhere.put(bean.getName(), t);
+    			return t;
+    		}
+    	}
+
+    	// Return an existing instance of a certain contextual type or a null value.
+    	public <T> T get(Contextual<T> contextual) {
+    		Bean bean = (Bean) contextual;
+    		// you can store the bean somewhere
+    		if (somewhere.containsKey(bean.getName())) {
+    			return (T) somewhere.get(bean.getName());
+    		} else {
+    			return null;
+    		}
+    	}
+      
+      // Determines if the context object is active.
+    	public boolean isActive() {
+    		return true;
+    	}
+
+    }
+
 ## Deactivatable
 
 DeltaSpike allows you to deactivate its own Extensions. You just need to implement your [ClassDeactivator](spi.html#classdeactivator).