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Posted to dev@felix.apache.org by "Felix Meschberger (JIRA)" <ji...@apache.org> on 2013/03/11 09:31:12 UTC
[jira] [Updated] (FELIX-3963) Properly handle method resolution
through reflection
[ https://issues.apache.org/jira/browse/FELIX-3963?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Felix Meschberger updated FELIX-3963:
-------------------------------------
Description:
An InventoryPrinter can be registered as an InventoryPrinter service implementing the interface or it can be registered as service of any type as long as a particular method signature is implemented (along with a number of service registration properties required in both cases).
The method signature is similar to the InventoryPrinter method is:
void print(String mode, PrinterWriter writer, boolean isZip)
Previously the ConfigurationPrinter support in Web Console 4.0 supported the same mechanism (with a slightly different signature, of course).
The question is, how is the method found:
(1) Use the service implementation class only to find any declared method. This is how Web Console 4.0 supports ConfigurationPrinter discovery.
(2) Use the service implementation class hierarchy to find a properly declared method. This is the current intent of the InventoryPrinter.
I think for the backwards compatibility use case (ConfigurationPrinter signatures) we should implement the "implementation-class-only" variant (1).
For new InventoryPrinter services we might consider variant (2). Yet I am not sure, whether this really is usefull: Does such a one-off InventoryPrinter service really support inheritance and method selection through the class hierarchy ? In such cases implementing the InventoryPrinter might make more sense.
See also the discussion at http://felix.markmail.org/thread/rtkogb7uukyt6gky
was:
An InventoryPrinter can be registered as an InventoryPrinter service implementing the interface or it can be registered as service of any type as long as a particular method signature is implemented (along with a number of service registration properties required in both cases).
The method signature is similar to the InventoryPrinter method is:
void print(String mode, PrinterWriter writer, boolean isZip)
Previously the ConfigurationPrinter support in Web Console 4.0 supported the same mechanism (with a slightly different signature, of course).
The question is, how is the method found:
(1) Use the service implementation class only to find any declared method. This is how Web Console 4.0 supports ConfigurationPrinter discovery.
(2) Use the service implementation class hierarchy to find a properly declared method. This is the current intent of the InventoryPrinter.
I think for the backwards compatibility use case (ConfigurationPrinter signatures) we should implement the "implementation-class-only" variant (1).
For new InventoryPrinter services we might consider variant (2). Yet I am not sure, whether this really is usefull: Does such a one-off InventoryPrinter service really support inheritance and method selection through the class hierarchy ? In such cases implementing the InventoryPrinter might make more sense.
> Properly handle method resolution through reflection
> ----------------------------------------------------
>
> Key: FELIX-3963
> URL: https://issues.apache.org/jira/browse/FELIX-3963
> Project: Felix
> Issue Type: Bug
> Components: Inventory
> Affects Versions: inventory-1.0.0
> Reporter: Felix Meschberger
> Assignee: Felix Meschberger
> Fix For: inventory-1.0.0
>
>
> An InventoryPrinter can be registered as an InventoryPrinter service implementing the interface or it can be registered as service of any type as long as a particular method signature is implemented (along with a number of service registration properties required in both cases).
> The method signature is similar to the InventoryPrinter method is:
> void print(String mode, PrinterWriter writer, boolean isZip)
> Previously the ConfigurationPrinter support in Web Console 4.0 supported the same mechanism (with a slightly different signature, of course).
> The question is, how is the method found:
> (1) Use the service implementation class only to find any declared method. This is how Web Console 4.0 supports ConfigurationPrinter discovery.
> (2) Use the service implementation class hierarchy to find a properly declared method. This is the current intent of the InventoryPrinter.
> I think for the backwards compatibility use case (ConfigurationPrinter signatures) we should implement the "implementation-class-only" variant (1).
> For new InventoryPrinter services we might consider variant (2). Yet I am not sure, whether this really is usefull: Does such a one-off InventoryPrinter service really support inheritance and method selection through the class hierarchy ? In such cases implementing the InventoryPrinter might make more sense.
> See also the discussion at http://felix.markmail.org/thread/rtkogb7uukyt6gky
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