Nirmal Fernando created STRATOS-777:
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Summary: Introduce subscription filters to intercept a new
subscription
Key: STRATOS-777
URL: https://issues.apache.org/jira/browse/STRATOS-777
Project: Stratos
Issue Type: New Feature
Components: Stratos Manager
Affects Versions: 4.0.0
Reporter: Nirmal Fernando
Assignee: Nirmal Fernando
Fix For: 4.1.0
Currently, there's no clean way to intercept a subscription request and do some
pre-processing. As of now, we do some pre-processing of a subscription request
in order to identify the need of a load balancer and act accordingly. I
currently have another use-case to intercept a subscription request and act
upon a parameter.
Hence, to make the code clean over there, I propose we introduce a Subscription
Filter chain where you could intercept a subscription request and do some
pre-processing before creating the actual subscription.
Following is the interface design, I've come up with.
/**
* Intercepts the flow of Cartridge Subscription.
* Implementations of this class would get executed before making the real
subscription.
*/
public interface SubscriptionFilter {
/**
* Do some pre-processing on a subscription request.
* @param cartridgeInfo {@link CartridgeInfo}
* @param subscriptionData {@link SubscriptionData}
* @return {@link Properties}, if there are any.
* @throws ADCException on a failure while processing.
*/
public Properties execute(CartridgeInfo cartridgeInfo, SubscriptionData
subscriptionData) throws ADCException ;
}
Filters could leverage these key-value pairs to pass properties into the main
subscription.
One existing use-case is passing LB subscription related properties to the main
subscription.
You would need to implement the interface and add the fully qualified class
name of it, to the META-INF/services folder in a file named
"org.apache.stratos.manager.subscription.filter.SubscriptionFilter" (I am
planning to use the Java ServiceLoader -
http://docs.oracle.com/javase/6/docs/api/java/util/ServiceLoader.html)
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