If the registry was built and loaded fine there is no reason for you to not get the service. But I can see arguments on either side. I have said this before and say it again, I would certainly like to see an exception thrown at least during build/load time.

-Harish

Geoff Longman wrote:

Wait a sec. Sure log errors when the modules are parsed. That makes sense.

But, if I'm a client and I call registry.getService() I absolutely want a
service or an exception! Otherwise I have to stick null checks in all over
the place.

Geoff
----- Original Message -----
From: "Harish Krishnaswamy" <[EMAIL PROTECTED]>
To: "Jakarta Commons Developers List" <[EMAIL PROTECTED]>
Sent: Tuesday, March 16, 2004 10:34 PM
Subject: Re: [Hivemind] ServiceImplementationFactory - no Exception (?)




Not throwing an exception is a conscious decision. HiveMind is a
microkernal to be thought of as a servlet container - it loads all
modules at startup and any problems with the descriptors will be
identified and logged at load time but will continue to run. I can see
an exception being thrown at load time when there is a problem but
certainly disagree with the idea of throwing exceptions at runtime. If a
service is not loaded properly you have two options - don't care or fix
it and reload it!

-Harish


Benjamin Tomasini wrote:




I have started to use Hivemind and have been successful in porting over
some existing work.  It is quite nice!  Very well thought out. Keeping
the service / proxy layer in place is cool.

One suggestion so far...

I had a case where my service object from Registry.getService came back
null.  One of the services used the BuilderFactory.  I was getting a
log4j ERROR message, but no exception was thrown to my app.  It was a
simple runtime error - a typo in a config file.

Looking further, I see that

in

org.apache.hivemind.ServiceImplementationFactory

the method

createCoreServiceImplementation(....)

does not throw an exception or anything.

It seems that this prevents calling applications from knowing about
problems creating a service.  I could always check for null in the
service object, but this isn't quite right, IMO.  Especially with the
lazy loading, I think burying any exception here is bad, especially for
apps that depend on a large number of services.

I would be willing to put some work into this and submit a patch if we
think we need some exception handling here.

Ben


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