First - wheter it's good or bad - Hivemind does not construct or initialize service-implementations when the Registry/modules/services are loaded/build. Services are lazy-loaded.
Second you get an exception with registry.getService() if you use the primitive model. This also enforces non-circularity, which is IMO anyway the better design.
Third if you are fine with an NPE, why are you not fine with an ApplicationRuntimeException, which will be thrown in exactly the same cases an NPE would be thrown?
Apart of this you get half-initilized service-proxies because of circular references - service CHICKEN wants service EGG set and vice versa. It's just so that you can't give B for full initilization a full-initialized A if A needs a full-initilized B.
Proxies have the advantages that in a multi-threaded enviroment lazy-loading is possible without a lot of locking and that trying to call a non fully setup service always leads to an exception (maybe later but sure).
On Thu, 18 Mar 2004 12:15:06 -0800, <[EMAIL PROTECTED]> wrote:
Please remember that I have only used HiveMind here for a few days, so feel free to add large grains of salt to these thoughts.
I think I see what you mean. Two me, there are two sides of this.
1. On the intial load of modules / services, I would like to see the application have a complete excepion chain to whatever is loading the registry. In specific, Intializable.initializeService does not throw an exception. If there is an error in here, it would be nice for the registry to know about it, log it, and invalidate the service.
2. On the getService side, here are my thoughs.
(A) If a service fails to initialze in step 1, have getService throw and exception, too. That is fine with me.
(B) If a service fails to initialize in setp 1, return null. This is also fine with me.
(C) If a service has an error initializing, say in Initializable.initializeServce, why would I want an instance of anything? To me, a half-initialized service is worse.
I want my service to run 100% out of the box, or have a good strong error, even an NPE from the calling application (B above). I see no value in pretending everything was ok.
On Thu, 18 Mar 2004 12:08:48 -0500 Harish Krishnaswamy <[EMAIL PROTECTED]> wrote:Let me ask you this, how are contemplating handling these exceptions? Are you going to be catching exceptions when ever you do a lookup or are you planning on letting these exceptions cascade up to the top and throw a message to the client. 'Cause either way would be no different than what it is now, wouldn't you say?
-Harish
[EMAIL PROTECTED] wrote:
Great! I may take my hand at a patch, but I fear am too new to this project to get my head around it. Maybe I will Bugzilla this one if I have some time.
Great product all in all. BTW, any thoughts for Intializable.initializeService() throwing an exception, too?
I don't want to open pandora's box here, but I hit a similar issue with that as well.
Ben
On Wed, 17 Mar 2004 23:32:04 -0500 Harish Krishnaswamy <[EMAIL PROTECTED]> wrote:
--
Christian Essl
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