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From Johnny Cass <johnny.c...@epiuse.com>
Subject Re: TODO: Rewrite DiskCache
Date Tue, 29 May 2001 10:29:05 GMT
Santiago Gala wrote:
> I have started development of a completely new implementation, where:
> - a Resource class would take care of URI (naming, policies, ...) and
> concurrent access issues, as well as being the interface towards the
> rest of the system.

So you would have a class (URIResource or something) representing URIs:
name, protocol, type, policies, expiration time, file, etc. that would
in a sense replace DiskCacheEntry? 

> - Different objects (using the State Pattern) would be plugged in
> resources to implement the actual policies, depending on
>     o type of resource (writable, non-cacheable, ...),
>     o resource state (stale, idle, loading, expired,...) which in turn
> depends on the type and policies, and
>     o access method (protocol, ...).

So there would be a few default implementations of the URIResource
interface available. Which type to instantiate would be determined based
on the resource's state?
> In this way, we could have a Hierarchy of resources, completely
> decoupled of the algorithm implementations (done through states). This
> would enable
> - writing of remote/cacheable resources (through HTTP PUT or WebDAV),

via an implementation of RemoteURIResource?

> - decoupling of the "file:" protocol for local/writable resources. This

via an implementation of LocalURIResource?

> is particularly important in the long term, as it gives a lot of
> headaches depending on servlet container and difficults distributed
> implementations and/or packed war execution.
> These changes would greatly reduce the current complexity, and make it
> easier to develop new resources/policies.

I agree! (If I understand it correctly :) )

> If you have spare time to help with this, we could continue this
> discussion in the list, and work together in these changes.

I would like that. I'm not entirely sure what exactly you have in mind,
but if we could agree on the interfaces I can start implementing. I
don't think I have *THAT* much time available to have all this done and
tested by May 4th. It does sound like a good place to start contributing
my first Jetspeed source patches.

Thanks for your help Santiago.
- Johnny

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