Re: hasService() and lookup() inconsistent results

[Stephen McConnell]

Jarosław Pałka wrote:
Thanks, we found this circular dependency, :))

But there is still one question about attribute named 
"optional". How does it work? I thought that when I set 
in dependency optional="true" and I don't provide
depenedency in block.xml, hasService() will return false.
Before a component is deployed Merlin verifies that the type is in fact 
deployable (in principal).  This means checking that all deployment and 
runtime dependencies are resolvable and that a candidate provider is 
assigned.  If a dependency is optional and a candidate cannot be 
assigned, merlin will not halt deployment.

I.e.:

  optional == true

    merlin applies best efforts to establish a
    a candidate before deployment - if a candidate
    is not found, deployment will continue -
    as such hasService may return false
  optional == false

    component dependency must be fulfilled otherwise
    deployment will not be allowed - hasService will
    always return true
Stephen.


Jarek

----- Original Message ----- 
From: "Stephen McConnell" <[EMAIL PROTECTED]>
To: "Avalon framework users" <[EMAIL PROTECTED]>
Sent: Wednesday, February 25, 2004 6:30 PM
Subject: Re: hasService() and lookup() inconsistent results

Jarosław Pałka wrote:

Hi

Here's a ex.getCause().printStackTrace() result

java.lang.IllegalStateException: Illegal attempt to resolve an service
from

a non-deployed appliance
[appliance:/mrt-vend-client/LocationViewContainerImpl].

The only way you will get this exception is if you have a circular
dependency.  I.e. A depends on B depends on A, etc.  Under 3.2.5
circular dependencies are not supported.  Under 3.3 circular
dependencies are ok providing the dependent is not referenced during the
deployment phase.
Stephen.



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