[jira] [Updated] (STRATOS-777) Introduce subscription filters to intercept a new subscription

["Imesh Gunaratne (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/STRATOS-777?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Imesh Gunaratne updated STRATOS-777:
------------------------------------
    Fix Version/s:     (was: 4.1.0 M1)
                   4.1.0-M1

> 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-M1
>
>
> 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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