[gentoo-java] CLASSPATH deprecated?

[gentoo-java] CLASSPATH deprecated?

[Matt Bucknall]

Hello,

In section 6 of the Gentoo Java Guide, it mentions that setting a
system-wide CLASSPATH should be considered deprecated because
applications should manage their own classpaths. This makes sense, but I
am wondering, how are applications expected to do this? If an
application needs to make use of a 3rd party JAR, does it have to
include it as part of its own installation so it knows which version it
is, and where it is located, or is there some less brute-force automated
means for an application to locate installed libraries?

Thanks,

Matt.

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Re: [gentoo-java] CLASSPATH deprecated?

[Federico Fissore]

There are mainly two ways to do this:

   1. use a "static" classpath in the form
      create symlinks to system installed jars and then run something like
      CLASSPATH="lib/commons-logging.jar:lib/commons-collections.jar"
      java MyApp
   2. ask java-config to do that for you
      CLASSPATH=$(java-config -dp commons-beanutils-1.6) java MyApp

My preference goes to the first way when packaging an application (if 
the application expects some jars in some folder) and to the second way 
when I run my own application (obvioulsy backed by a shell script: I 
hate writing the same stuff twice)

Matt Bucknall wrote:
> Hello,
>
> In section 6 of the Gentoo Java Guide, it mentions that setting a
> system-wide CLASSPATH should be considered deprecated because
> applications should manage their own classpaths. This makes sense, but I
> am wondering, how are applications expected to do this? If an
> application needs to make use of a 3rd party JAR, does it have to
> include it as part of its own installation so it knows which version it
> is, and where it is located, or is there some less brute-force automated
> means for an application to locate installed libraries?
>
> Thanks,
>
> Matt.
>
> Send instant messages to your online friends http://uk.messenger.yahoo.com 
>   

-- 
: Federico Fissore
:   Blog : http://www.fridrik.it/blog/
: Jabber : federico@jabber.fsfe.org
---------+-----------------------------------------------------
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  [][][] | speech 'cause then you get some really free speech"
    ||   :                                            Dick Wall

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Re: [gentoo-java] CLASSPATH deprecated?

[Matt Bucknall]

Hi Federico,

Thanks for your reply. My understanding is that java-config is specific
to Gentoo. I assume then, there is no cross-platform means of finding
out whether/where libraries are installed automatically (i.e. for use by
some installation process). Is it normal practice when deploying a Java
application to include all the JARs that it needs so not to rely on the
end-user having some packages already pre-installed?

Thanks again,
Matt.


Federico Fissore wrote:
> There are mainly two ways to do this:
>
>   1. use a "static" classpath in the form
>      create symlinks to system installed jars and then run something like
>      CLASSPATH="lib/commons-logging.jar:lib/commons-collections.jar"
>      java MyApp
>   2. ask java-config to do that for you
>      CLASSPATH=$(java-config -dp commons-beanutils-1.6) java MyApp
>
> My preference goes to the first way when packaging an application (if
> the application expects some jars in some folder) and to the second
> way when I run my own application (obvioulsy backed by a shell script:
> I hate writing the same stuff twice)
>
> Matt Bucknall wrote:
>> Hello,
>>
>> In section 6 of the Gentoo Java Guide, it mentions that setting a
>> system-wide CLASSPATH should be considered deprecated because
>> applications should manage their own classpaths. This makes sense, but I
>> am wondering, how are applications expected to do this? If an
>> application needs to make use of a 3rd party JAR, does it have to
>> include it as part of its own installation so it knows which version it
>> is, and where it is located, or is there some less brute-force automated
>> means for an application to locate installed libraries?
>>
>> Thanks,
>>
>> Matt.
>>
>> Send instant messages to your online friends
>> http://uk.messenger.yahoo.com   
>

Send instant messages to your online friends http://uk.messenger.yahoo.com 

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Re: [gentoo-java] CLASSPATH deprecated?

[Petteri Räty]

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Matt Bucknall kirjoitti:
> Hi Federico,
> 
> Thanks for your reply. My understanding is that java-config is specific
> to Gentoo. I assume then, there is no cross-platform means of finding
> out whether/where libraries are installed automatically (i.e. for use by
> some installation process). Is it normal practice when deploying a Java
> application to include all the JARs that it needs so not to rely on the
> end-user having some packages already pre-installed?
> 
> Thanks again,
> Matt.
> 
> 

Nope, not in the java world. Hopefully we will have something like
auto*, pkg-config etc in the java world too some day. It seems to be
very usual for upstreams to include all the dependencies inside their
source packages but the Linux distributions would appreciate if you also
distributed a src tarball without these dependencies to save bandwidth
and disk space. Packages are not going to use the bundled stuff.

Regards,
Petteri Räty (Betelgeuse


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Re: [gentoo-java] CLASSPATH deprecated?

[Matt Bucknall]

Okay. Thanks for the help.


Petteri Räty wrote:
> Matt Bucknall kirjoitti:
>   
>> Hi Federico,
>>
>> Thanks for your reply. My understanding is that java-config is specific
>> to Gentoo. I assume then, there is no cross-platform means of finding
>> out whether/where libraries are installed automatically (i.e. for use by
>> some installation process). Is it normal practice when deploying a Java
>> application to include all the JARs that it needs so not to rely on the
>> end-user having some packages already pre-installed?
>>
>> Thanks again,
>> Matt.
>>
>>
>>     
>
> Nope, not in the java world. Hopefully we will have something like
> auto*, pkg-config etc in the java world too some day. It seems to be
> very usual for upstreams to include all the dependencies inside their
> source packages but the Linux distributions would appreciate if you also
> distributed a src tarball without these dependencies to save bandwidth
> and disk space. Packages are not going to use the bundled stuff.
>
> Regards,
> Petteri Räty (Betelgeuse
>
>   

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Re: [gentoo-java] CLASSPATH deprecated?

[Greg Tassone]

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On Saturday 18 November 2006 06:04, Matt Bucknall wrote:
...
> I assume then, there is no cross-platform means of finding
> out whether/where libraries are installed automatically (i.e. for use by
> some installation process).

That is correct.  Java leaves that to the user and/or the user's operating 
system to configure as desired.


> Is it normal practice when deploying a Java 
> application to include all the JARs that it needs so not to rely on the
> end-user having some packages already pre-installed?

Yes, this is quite common.  IMO this is primarily born out of the 
cross-platform nature of most Java applications combined with simplification 
(or laziness) by the program author(s).

A nice balance between the extremes was already mentioned by Petteri Raty:  
offer archives without library dependencies for easier inclusion into 
installers (and operating systems like Gentoo).  That way the user and 
operating system maintainers can pick the best option for their needs.

~ Greg

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