useOrigin and caching of files

[Pa...@nokia.com]

>No, because useOrigin is only an hint to the cache 
>implementation. Those resources can't be used at their 
>original location (after resolve, artifacts must be available 
>as files, so only files can't be used from their original 
>location). Hence even with useOrigin="true" Ivy will actually 
>download and cache the remote resources and use the original 
>location of the "local"
>artifacts (local can be actually a network accessible filesystem).

Xavier,

Related to your comment above, if we have repositories that are not
local and cannot easily be represented as a filesystem, but also the
content cannot or should not be downloaded and cached as you describe,
what options are there for dealing with that? As I mentioned, we are
interested in using Ivy but our content in many situations is way to
large to have Ivy handle in its normal manner.

Is there any way to fake artifacts being available as files? Or prevent
that happening during resolve? Could Ivy be enhanced in any way to
handle this kind of use case?

Would it be possible to do a custom download via an event hook and then
have Ivy report the files are available? 

When I first started reading about Ivy I made the assumption that
resolve was purely about determining if all the dependencies are
available and where they could be obtained from, but it seems it is a
little more complex than that.

Thanks for all the assistance!

paul

Re: useOrigin and caching of files

[Xavier Hanin <xa...@gmail.com>]

On Wed, Apr 9, 2008 at 6:42 AM, <Pa...@nokia.com> wrote:

> >No, because useOrigin is only an hint to the cache
> >implementation. Those resources can't be used at their
> >original location (after resolve, artifacts must be available
> >as files, so only files can't be used from their original
> >location). Hence even with useOrigin="true" Ivy will actually
> >download and cache the remote resources and use the original
> >location of the "local"
> >artifacts (local can be actually a network accessible filesystem).
>
> Xavier,
>
> Related to your comment above, if we have repositories that are not
> local and cannot easily be represented as a filesystem, but also the
> content cannot or should not be downloaded and cached as you describe,
> what options are there for dealing with that? As I mentioned, we are
> interested in using Ivy but our content in many situations is way to
> large to have Ivy handle in its normal manner.

If you use the Ivy API rather than Ivy ant tasks, you can disable download
of artifacts (with the resolve option you've only found). But the question
is what to you want to do with the result. Usually the post resolve
operations require to access to artifacts as files, that's why Ivy makes
this part of the resolve process. But maybe if we learn more about your use
case we may see a benefit of improving Ivy to support it.

>
>
> Is there any way to fake artifacts being available as files? Or prevent
> that happening during resolve? Could Ivy be enhanced in any way to
> handle this kind of use case?

You can fake artifacts if you want, it's pretty easy to generate an empty
file or a file containing the actual remote location of the artifact. Once
again, it only depends on what you later need to do with your artifacts.

>
>
> Would it be possible to do a custom download via an event hook and then
> have Ivy report the files are available?

I don't think you need an event hook, you can use a custom resolver for
this. The resolver can launch a custom download in a separate thread and
report to Ivy core engine that it has done its job.


>
> When I first started reading about Ivy I made the assumption that
> resolve was purely about determining if all the dependencies are
> available and where they could be obtained from, but it seems it is a
> little more complex than that.

Indeed, the resolve process both resolve dependencies and download artifacts
to cache. As I said you can disable the download from the API, and then call
the download with the API too. But this is not possible using existing
tasks, and it would be a big change in Ivy behavior to support this in tasks
(eg what happen if you call a post resolve task like cachepath if you
disabled artifact download during resolve?).

Xavier

>
>
> Thanks for all the assistance!
>
> paul
>



-- 
Xavier Hanin - Independent Java Consultant
http://xhab.blogspot.com/
http://ant.apache.org/ivy/
http://www.xoocode.org/