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From Nicolas Lalevée <nicolas.lale...@hibnet.org>
Subject Re: IvyDE cache location
Date Sat, 17 Jan 2009 09:03:49 GMT

Le 16 janv. 09 à 23:07, Mitch Gitman a écrit :

> Nicolas, correct me if I'm misstating something, but I look at an
> ivy:retrieve-like capability as a nice-to-have but not necessary  
> feature for
> IvyDE.
>
> IvyDE itself really just exists as a nice convenience, so that  
> classpaths
> resolve correctly in Eclipse. How it does that--whether with  
> ivy:cachepath
> or with an ivy:retrieve to a specified directory--is somewhat of an
> implementation detail in this respect. Either way, the
> ClassNotFoundExceptions go away.
>
> The tool of record is still the build script itself. Once you have  
> IvyDE
> doing Ivy retrieves to the lib directory that the build script is  
> doing
> retrieves to, it kind of feels to me like you're letting the IDE (the
> second-class citizen) encroach into the realm of the build script (the
> first-class citizen).

I agree with you the reference should be the ant build system. For  
instance eclipse can only manage one classpath by project, whereas we  
usually use it to compile, run and test. So in my projects I ask IvyDE  
to get 3 configurations: compile, runtime and test. But in ant the  
javac task use an ivy cachepath with only the compile configuration,  
for the junit task only the test configuration and for the building of  
some war only the runtime configuration.
Eclipse setup should be as close as possible to the build and  
deployment environment, but it is not the case.

> That concern aside, suppose the developer has blown away their Ivy  
> cache. I
> don't see why the issue Aaron describes cannot be addressed simply by
> right-clicking on the Ivy icon in Package Explorer and selecting  
> Resolve.
> Granted, it takes a little getting used to for developers to get in  
> the
> habit of this, but this seems like part of the contract of using  
> Ivy. As an
> Ivy consumer, you need to have some understanding as to when a  
> resolve is
> necessary.

Well, I don't know what size is Aaron's project, how theses projects  
are interconnected. But If you have 20 projects all relying on some  
maven repository, it will really painful to do a resolve on every  
project.

Maybe the real debatable question here is why the cache need to be  
cleaned, normally it shouldn't. The cache is not aimed to modify how  
the resolve process occurs, just speed it up. Actually I see only two  
reasons that should stay exceptional:
* the size of the cache
* a repository has been setup with checkmodified=false but a broken  
ivy.xml on that repository has been fixed

Nicolas

>
>
> On Fri, Jan 16, 2009 at 1:40 PM, Nicolas Lalevée <nicolas.lalevee@hibnet.org
>> wrote:
>
>>
>> Le 16 janv. 09 à 06:25, Yu, Aaron (IT) a écrit :
>>
>>
>> Hi,
>>>
>>> I have a problem of using Ivy and IvyDE.
>>> At my firm we are in the process of switching to Ivy for managing  
>>> our
>>> java dependencies. We do not want thousands of developers to resolve
>>> dependencies in  different  ways so we provide a centralized ,  
>>> read-only
>>> ivy-settings.xml file  which is used by all developers. However,  
>>> this
>>> presents us with a problem. We would like to  make it possible for  
>>> our
>>> users to set their own cache locations, because if  they  use the  
>>> same
>>> cache location for all projects, when  they clean the cache in one
>>> project, the whole cache location will be cleaned, and this  will  
>>> crash
>>> the building of other projects.
>>>
>>> I know we can create a project-specific ivy-settings.xml file, and  
>>> use
>>> 'defaultCacheDir', 'resolutionCacheDir' and 'repositoryCacheDir'
>>> attributes in 'caches' element to set the project-based cache  
>>> location.
>>> But as I mentioned above, to make all the projects more manageable  
>>> and
>>> shareable, we do not encourage developers to have the project- 
>>> specific
>>> ivy setting file.
>>>
>>> To get around this we have implemented a new properties page for the
>>> ivyde plugin under the existing one called simply 'Cache'. This  
>>> allows a
>>> user to choose the cache location. The choices are: Default
>>> ($HOME/.ivy2) and Workspace (workspace_dir/.metadata/.ivy2). We then
>>> reset the ivy.home System property and trigger re-resolution of all
>>> project ivy classpath containers when the users changes this setting
>>> (the change affects all projects in the workspace since ivy core  
>>> reads
>>> the ivy.home System property to find out where it should do its
>>> caching). However, we are now wondering if what is really needed  
>>> is a
>>> private cache area for each project in the workspace, for example:
>>> workspace_dir/.metadata/.ivy2/project_name. But this is not  
>>> possible at
>>> the moment due to the way in which ivy core decided where to place  
>>> its
>>> cache. (And, as we said, we do not want users to have to specify  
>>> their
>>> own ivy-settings for each project for this reason alone.)
>>>
>>> Other people at our firm have also pointed out that it might be  
>>> better
>>> if ivy core used a version specific cache location by default since
>>> there could be differences in cache metadata between versions. This
>>> would cause cache corruption if different versions of ivy core  
>>> were run
>>> on the same system.
>>>
>>> All this seems to indicate that the subject of caching needs  
>>> rethinking
>>> in ivy core and ivyde, and we would like to ask for some  
>>> suggestions on
>>> this.
>>>
>>
>> It seems to me that the way you want to use caching is actually  
>> like using
>> the retrieve job.
>> The retrieve job would get the dependencies and put it in your  
>> project lib
>> directory (somehow your by-project cache), and the IvyDE would  
>> build the
>> classpath based on the content of that lib directory.
>> Unfortunately this feature is not implemented yet:
>> https://issues.apache.org/jira/browse/IVYDE-56
>>
>> Nicolas
>>
>>


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