I am working with Maven on some fairly complex projects and I now
understand that the dependency resolution is done via a "nearness"
process rather than based on the highest compatible version. I have
recently upgraded from Maven 2.04. to 2.0.5 which did not fix my
issue but did change the behavior a little. Here is my problem:
I have a number of framework libraries I am using including Spring,
Hibernate, etc. I have an artifact that uses Hibernate at the latest
version which in turn uses Commons-Collections 3.1. In that same
project I use some new methods out of Commons-Collections 3.2 so I
have that referenced in my pom.xml as well. The issue comes when i
try to use that artifact and another artifact that uses Hibernate.
Depending on the order that I include those dependencies I sometimes
get 3.1 and sometimes 3.2. If I get 3.1 my code breaks at run time.
Now this evening I included another artifact that is using a
framework that apparently used Commons-Collections 2.1 and now my War
includes Commons-Collections 2.1 and that breaks everything. I can
see the resolution of the libraries in the -X output of the mvn
command but no idea how to fix it or why it is happening. I know I
can fix the issue by including every artifact that is used by every
other artifact in my pom.xml at the version I want but that seems to
defeat the whole purpose of transitive dependencies. There are also
cases where a dependency may read 1.7) and 1.6 and I get null
pointers during my builds even though 1.7 should be upwardly
compatible with 1.6.
So here are my questions:
Why was the "nearness" process chosen and what does it buy me over
using the most current compatible version out of my entire dependency
list?
How can I insure that I don't get my dependencies randomly downgraded
so that I get runtime errors with no indication until I use the
application?
Is there a report or process I can use to locate these downgrades so
I can deal with them during build time and not runtime?
Am I missing something or doing something wrong that is causing this
behavior?
Thanks for all the support and a great open source offering. I hope
you can educate me so I can deal with this issue and teach others.
Scott Ryan
CTO Soaring Eagle L.L.C.
Denver, Co. 80129
www.soaringeagleco.com
www.theryansplace.com
(303) 263-3044
[EMAIL PROTECTED]
