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From "Andrus Adamchik (JIRA)" <j...@apache.org>
Subject [jira] Updated: (CAY-1508) Support for DataChannel filters
Date Sun, 14 Nov 2010 03:35:14 GMT

     [ https://issues.apache.org/jira/browse/CAY-1508?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Andrus Adamchik updated CAY-1508:
---------------------------------

    Description: 
Support for DataChannel filters with API similar to ServletFilters, only adapted for Cayenne
(i.e. it will be mirroring DataChannel onQuery and onSync methods) :

public interface DataChannelFilter {
    
    void init(DataChannel channel);

    QueryResponse onQuery(
            ObjectContext originatingContext,
            Query query,
            DataChannelFilterChain filterChain);

    GraphDiff onSync(
            ObjectContext originatingContext,
            GraphDiff changes,
            int syncType,
            DataChannelFilterChain filterChain);
}

One difference with ServletFilter is the absence of  "destroy" method in DataChannelFilter.
Destroy is achieved via @BeforeScopeEnd annotation per filter. 

DataChannelFilters may be good for tying multiple object lifecycle events together in one
context, monitoring performance at the ObjectContext-level, and other good things.

TODO: One possible consequence of this feature is that channel decorators will provide no
advantage as a design pattern, and relationships between ObjectContext and its parent DataChannel
may not require such a high-level of abstraction (a leaky abstraction for that matter). E.g.
we may get rid of DataDomainQuery, returning parent domain the old way via API calls.

  was:
Support for DataChannel filters with API similar to ServletFilters, only adapted for Cayenne
(i.e. it will be mirroring DataChannel onQuery and onSync methods) :

public interface DataChannelFilter {
    
    void init(DataChannel channel);

    QueryResponse onQuery(
            ObjectContext originatingContext,
            Query query,
            DataChannelFilterChain filterChain);

    GraphDiff onSync(
            ObjectContext originatingContext,
            GraphDiff changes,
            int syncType,
            DataChannelFilterChain filterChain);
}

One difference with ServletFilter is the absence of  "destroy" method in DataChannelFilter.
Destroy is achieved via @BeforeScopeEnd annotation per filter. 

TODO: One possible consequence of this feature is that channel decorators will provide no
advantage as a design pattern, and relationships between ObjectContext and its parent DataChannel
may not require such a high-level of abstraction (a leaky abstraction for that matter). E.g.
we may get rid of DataDomainQuery, returning parent domain the old way via API calls.


> Support for DataChannel filters
> -------------------------------
>
>                 Key: CAY-1508
>                 URL: https://issues.apache.org/jira/browse/CAY-1508
>             Project: Cayenne
>          Issue Type: Task
>          Components: Core Library
>    Affects Versions: 3.1M1
>            Reporter: Andrus Adamchik
>            Assignee: Andrus Adamchik
>             Fix For: 3.1M1
>
>
> Support for DataChannel filters with API similar to ServletFilters, only adapted for
Cayenne (i.e. it will be mirroring DataChannel onQuery and onSync methods) :
> public interface DataChannelFilter {
>     
>     void init(DataChannel channel);
>     QueryResponse onQuery(
>             ObjectContext originatingContext,
>             Query query,
>             DataChannelFilterChain filterChain);
>     GraphDiff onSync(
>             ObjectContext originatingContext,
>             GraphDiff changes,
>             int syncType,
>             DataChannelFilterChain filterChain);
> }
> One difference with ServletFilter is the absence of  "destroy" method in DataChannelFilter.
Destroy is achieved via @BeforeScopeEnd annotation per filter. 
> DataChannelFilters may be good for tying multiple object lifecycle events together in
one context, monitoring performance at the ObjectContext-level, and other good things.
> TODO: One possible consequence of this feature is that channel decorators will provide
no advantage as a design pattern, and relationships between ObjectContext and its parent DataChannel
may not require such a high-level of abstraction (a leaky abstraction for that matter). E.g.
we may get rid of DataDomainQuery, returning parent domain the old way via API calls.

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