Re: [equinox-dev] Service Component circular dependencies

[Roy Paterson <rpatersn@xxxxxxxxxx>]

Sounds like it could be a bug.  Declarative
Services supports Circular Dependencies so long as at least one dependency
in the cycle is optional.  If there is no optional dependency an exception
should be thrown by the SCR resolver.

I can't think of a way that DS could
support a cycle of Circular Dependencies without any optional dependencies
- any ideas you have would be great.

Please open a bug and attach your service
components that demonstrate the problem.

Thanks,
Roy

-----------------------------------------
Roy Paterson
IBM Pervasive Computing
Austin, TX
Phone: (512) 838-8898

Subbarao Meduri/Durham/IBM@IBMUS
Sent by: equinox-dev-bounces@xxxxxxxxxxx

06/28/2006 11:46 AM

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Subject	[equinox-dev] Service Component circular dependencies

It appears that the Declarative Services runtime can potentially
instantiate a delayed service component multiple times.

In the scenario I have, a delayed service component A is called on activate()
method after it is looked up in the service registry, and as part of processing
the activate code, somewhere deep in the call stack, the service for component
A is looked up again (using service registry APIs). This is clearly a mandatory
circular dependency that DS does not support. I would have expected an
exception thrown at this time indicating a potential circular dependency.
Instead, it appears that the DS runtime tries to instantiate and activate
the component again, which seems like a bug.

On the other hand, IOC frameworks such as Spring/Pico seem to have a way
to deal with circular references. would it be possible that DS runtime
to support mandatory circular references, and not have such restriction
?

Appreciate your thoughts.

Regards,
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