On 01/06/2012 8:29 PM, Rolf Lear wrote:
Hi again everyone.
I have taken some time and installed a nexus locally, and I have been
playing with different alternatives for how to solve my problem....
To recap, I have JDOM versions 1.x and 2.x both currently deployed in
the artifact 'jdom' even though these versions internally have
different packages (org.jdom.* and org.jdom2.* ). The problem is that
it is necessary in some conditions to have both version 1.x and 2.x in
a maven project (typically because the 1.x version is used by some
third-party dependency).
Why will the 2.x version not work with code that was written to the 1.x
spec?
I have been trying to find the 'best' way to 'recover' the mess in the
JDOM artifact so that it is possible to have both 1.x as well as 2.x,
but to do it in such a way that it has the least impact on current
users, and for those users who *need* both versions, it can be done as
simply as possible.
In my experimentation I think I have found that the *easiest* and also
the *neatest* solution is to duplicate the latest JDOM 1.x artifact
with a different artifact-id. In my local nexus I have duplicated the
JDOM 1.1.3 artifact as jdom.dep 1.1.3.
The way I see this working is that for the 'simple' user, they do not
have the complicated requirement to have both 1.x and 2.x. In their
case they can just continue doing what they do.... and when they are
ready they can upgrade their code to use JDOM 2.x, changing their
dependency from jdom 1.x to jdom 2.x when they do.
For the complicated user, they will be needing both versions. Right
now they can't run their code because they can't have both 1.x and 2.x
in their compile. In the typical case there is a third-party
dependency which in turn depends on jdom 1.x. Since 'our' project
depends on jdom 2.x and the 3rd party depends on 1.x, maven will
automatically just pull the 'newer' jdom 2.x version. This means that
the 3rd-party code will be failing because it is missing classes.
Why not add the classes back into 2.x that were removed?
In this case, we can simply add the 'jdom.dep' artifact to our
project, specifying the 1.x version.
I have 'worked through' the various scenarios, and I think it can be
expressed as follows:
Say I have my project. It has the simple dependency:
<dependency>
<groupId>org.jdom</groupId>
<artifactId>jdom</artifactId>
<version>2.0.1</version>
<scope>compile</scope>
</dependency>
Now I want to include the additional dependency (this is just some
'arbitrary' dependency which has an internal dependency to jdom 1.1):
<dependency>
<groupId>net.sourceforge.htmlcleaner</groupId>
<artifactId>htmlcleaner</artifactId>
<version>2.2</version>
</dependency>
Unfortunately this htmlcleaner code will not work because I am missing
the org.jdom.* classes because maven has only used the jdom 2.0.1
version which only has the org.jdom2.* classes.
The solution is, in my project, to also include the 'duplicate' 1.x
dependency:
<dependency>
<groupId>org.jdom</groupId>
<artifactId>jdom.dep</artifactId>
<version>1.1.3</version>
</dependency>
The bottom line is that only those people who require both versions
will be affected, and the solution only requires adding a new
dependency to the project, and there is no need to do 'exclusions' or
other 'shady' logic....
Further, there is no need for the 'normal' JDOM user (they only
require the one version of JDOM) to worry about anything because
things just stay the same.... there is nothing to change.
I would greatly appreciate it if this 'plan' could be inspected and
criticized/poked/verified/etc.
Thanks in advance
Rolf
On 29/05/2012 11:38 AM, Rolf Lear wrote:
On Tue, 29 May 2012 16:22:27 +0100, Stephen Connolly
<[email protected]> wrote:
On 29 May 2012 15:26, Rolf Lear<[email protected]> wrote:
So, being inexperienced, my intention is to find some solution that:
1. makes it possible (even if playing exclusion games is needed) to
use
both JDOM 1.x and 2.x in a maven project (currently it is not).
Well actually it is possible to work around the issue if you are
prepared to introduce a wrapper project...
something like this:
Hmmm... this has gone over my head.... I think I am going to have to
spend
some time getting to grips with some of the more details in maven...
Perhaps I should take a few days and set up my own repo, and try these
things out...
For what it's worth, I am not sure the maven-shade-plugin is
appropriate.... is it? I am not sure how that usage of it helps... I
simply
don't know enough.
Bottom line is that I don't know enough yet... must learn more.
Thanks all, I'll figure some more things out and come back with 'more
of a
clue'.
Rolf
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