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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: [POLL] loading XML configurations from filesystem
Date Tue, 20 May 2008 17:45:30 GMT
Fair enough... I may have intentionally exaggerated the portability  
claim and may argue about changing your specific setup (e.g. deploying  
a full war or a jar to that single shared point of the server farm),  
but I agree with you calling this the "ideal world", with real world  
being all made of exceptions and edge cases.

As a practical matter I think we can support (1) and (2) in a multi- 
cayenne.xml runtime (after all, files can be identified via URL's just  
as well as jar components). And support (3) as well, detecting  
conflicts on the fly and throwing an exception (2 DataMaps with the  
same name located outside of any project roots, how do we merge them?)

So the refactoring I mentioned is not strictly necessary for things to  
move forward. Although leaving them the way they are adds to the  
Configuration hair ball... So it is very tempting to just leave it up  
to the users to handle at least #3 by extending Configuration (per my  
reply to Kevin, many cases of #3 would actually become obsolete).

Andrus


On May 20, 2008, at 7:22 PM, Philip Miller wrote:
> Portability means different things in different contexts.
>
> For example I might write an application which reads its config from a
> UNC file path (\\foo\bar\cayenne.xml). That application is portable to
> any environment which can see that path. It allows me to administer
> configuration of an indefinitely scalable server farm from a single
> point. That might be a desirable design feature in the context of my
> application.
>
> To answer your question I've used 1,2 and 3 at various times when it  
> was
> appropriate to compromise on the ideal world solution.
>
> Phil
>
>
>> -----Original Message-----
>> From: Andrus Adamchik [mailto:andrus@objectstyle.org]
>> Sent: 20 May 2008 15:39
>> To: user@cayenne.apache.org
>> Subject: [POLL] loading XML configurations from filesystem
>>
>> Wanted to check if anybody loads "cayenne.xml" and related
>> Map and Node XML files from locations other than default two:
>> CLASSPATH and WEB-INF/ ?  More specifically:
>>
>> 1. anybody uses FileConfiguration?
>> 2. anybody uses DefaultConfiguration (with 'addResourcePath' or
>> without) to directly reference file in the filesystem (vs.
>> referencing resources in classpath)?
>> 3. anybody places DataMap / DataNode files in (jar)
>> directories outside of the directory where "cayenne.xml" is located?
>>
>> I personally don't, as all these approaches lead to
>> non-portable applications that make unwarranted assumptions
>> about the environment.
>> I think cases requiring to open cayenne.xml via the
>> application UI are special enough to warrant a custom configuration.
>>
>> Some background. I am planning a rework of the config package
>> to include support for merging of multiple Cayenne projects
>> into a single "virtual project" in runtime (hence enabling
>> multiple "persistent units" in the app). So I am looking to
>> simplify this task and stop supporting edge cases that are
>> not widely used, and also change the basic algorithm of
>> resolving files relative to cayenne.xml to ensure they are
>> actually relative to the URL within a JAR or class folder
>> where cayenne.xml is found (so that we can have multiple
>> cayenne.xml files and avoid conflicts when loading dependent
>> XML files of those).
>>
>> I think there is a lot of benefit in keeping the built-in
>> choices of file lookup down to just a few basic ones, and of
>> course the users can still write their own Configuration
>> extensions to address non-standard requirements.
>>
>> Andrus
>>
>>
>>
>
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