[seek-dev] EcoGrid Query Service: Instances and Factories

[Bing Zhu]

Matt,

In today's SEEK meeting at SDSC, we also talked about the possibility for
developers other than
Ecogrid developers to build their client(s) based on WSDLs of ecogrid
services. Using of Factory
model apparently makes it impossible for others to do so.

If we have such a request from other groups, I agree with your suggestion
that we have to go
back to a non-Factory approach. Question is if this approach can handle
multiple connections
simultaneously.

Sincerely,
Bing



-----Original Message-----
From: seek-dev-admin at ecoinformatics.org
[mailto:seek-dev-admin at ecoinformatics.org]On Behalf Of Matt Jones
Sent: Tuesday, January 20, 2004 5:10 PM
To: seek-dev
Subject: [seek-dev] EcoGrid Query Service: Instances and Factories


EcoGrid team,

I've been working on the registry issues, and have run into some issues
with the way Jing and Bing are using the Grid "Factory" pattern.  As
they have implmented it, each wrapped server (like a metacat or srb)
exposes a "Factory" which has a "createInstance" method.  When called, a
new endpoint is created that exposes the methods in our
EcoGridQeuryLevelOne interface spec.  This endpoint is then queried by
only that one client.  However, this pattern makes it very hard for us
to discover where the EcoGridQueryLevelOne services reside, because they
don't exist at the time that the client is querying the registry.

I don't see what we gain from using the factory pattern here at all
(given our underlying server systems), so I am proposing we eliminate
use of Factories and just stick to EcoGridQueryLevelOne instances.  I
think that doing so would substnatially simplify the demands on clients
in the service discovery pahse while clients are querying the registry.
  The details aof how I arrived at that proposal with Jing are in the
attached IRC conversation.

Please review this information and let me know if you think it is a good
idea to eliminate the use of factories.  Thanks,

Matt

PS We're on a tight time schedule, so prompt feedback is appreciated.
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Matt Jones                                     jones at nceas.ucsb.edu
http://www.nceas.ucsb.edu/    Fax: 425-920-2439    Ph: 907-789-0496
National Center for Ecological Analysis and Synthesis (NCEAS)
University of California Santa Barbara
Interested in ecological informatics? http://www.ecoinformatics.org
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