Re: [HiveMind] I don like HiveMind.getDefault and setDefault(Registry)

[Harish Krishnaswamy]

What if you had two applications running under the same context though? 
And how will replication be taken care of, I thought context attributes 
are not replicated in a clustered environment. And, yes the 
constructDefaultRegistry will definitely be helpful.

-Harish

Howard M. Lewis Ship wrote:

I think the TapestryApplicationServlet should build the registry and store it as a 
ServletContext
attribute.  In addition, the IEngine interface should include a property pointing to 
the shared
Registry instance.
--
Howard M. Lewis Ship
Creator, Tapestry: Java Web Components
http://jakarta.apache.org/tapestry
http://jakarta.apache.org/commons/sandbox/hivemind/
http://javatapestry.blogspot.com
 

-----Original Message-----
From: Harish Krishnaswamy [mailto:[EMAIL PROTECTED] 
Sent: Sunday, September 14, 2003 7:58 PM
To: Jakarta Commons Developers List
Subject: Re: [HiveMind] I don like HiveMind.getDefault and 
setDefault(Registry)

So, in a webapp environment what is the best place to hold 
the registry? 
Is it the Global? Or do you think pages will also be a part of the 
registry that there will be no need at all for a registry reference, 
that is of course after Tapestry is refactored?

-Harish

Howard M. Lewis Ship wrote:

   

I'm thinking you are right ... its the balance of convienience vs. 
correctness.  Certainly, no service implementation should ever use 
HiveMind.getDefault() ... the BuilderFactory means they 
     

never need to 
   

find out the registry at all.  The idea was to provide a convienient 
place for application code to get at the registry, to get at 
     

services.
   

Still, I'm now leaning in your direction (removing it); it has the 
potential to cause too many problems once you introduce 
     

class loaders 
   

and the like.

--
Howard M. Lewis Ship
Creator, Tapestry: Java Web Components 
http://jakarta.apache.org/tapestry
http://jakarta.apache.org/commons/sandbox/hivemind/
http://javatapestry.blogspot.com



     

-----Original Message-----
From: Essl Christian [mailto:[EMAIL PROTECTED]
Sent: Friday, September 12, 2003 10:57 AM
To: [EMAIL PROTECTED]
Subject: [HiveMind] I don like HiveMind.getDefault and 
setDefault(Registry)

The reason I don't like this is because I guess it can lead
to quite some 
problems and it is not realy needed.

Just imagine your app uses HiveMind and some api uses
HiveMind internally 
but does not document (it is just internal why should it?). 
Both register 
with setDefault(). Than you have a problem which is not realy 
easy to find.

The same can happen everywhere where there are different
ClassLoaders. 
Think of a tomcat setup where HiveMind is in the 
RootClassLoader. Imagine 
two different web-apps use HiveMinde (and I think this will 
be no rare 
case). Each registers its own Registry. Both will end up 
       

sharing one 
   

Registry and which one is more or less a matter of luck. This 
is realy hard 
to debug.

Both Service and user code which use the getDefault() will be
more or less 
useless.

You also don't realy need the getDefault(). Services should take the
Registry to which they belong from the initialize() method or 
let it set as 
a property. And user code should provide its own way to 
access its service. 
A user defined static method could be enough (its not realy hard to 
implement).

So I want to recommend (because HiveMind is quite new) to
just remove the 
methods or deprecate them, before users start using them.



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