Why does M2Eclipse complain about missing artifact when mvn command line doesn't?

I've just set up a brand new installation of Eclipse Helios and have configured M2Eclipse to use an external (v 2.2.1) installation of Maven.

The system compiles fine on the command line, but from within M2Eclipse several of my project modules have an error:

Missing artifact javax.jms:jms:jar:1.1:test

I can get past the error by excluding the jms artifact from the Atomikos dependencies. But my main question is how can the two provi开发者_StackOverflow社区de different results!

Even more odd is that I have another installation of Eclipse Helios and everything works fine.

The dependency resolver in m2eclipse is not using the external Maven installation, it has to use the embedded Maven version. So, I'd recommend to get the latest version of m2eclipse, as well as Maven 3.x version to minimize the difference in dependency resolution.

Additionally, it is possible that you had some alternative repositories defined in your maven 2.2.1 conf/settings.xml file. If you use the embedded maven3 these will be ignored.

You also can specify your maven 2.2.1 installation as the maven installation for m2eclipse.

I posted a similar question and finally found an answer. See m2eclipse says "Missing artifact" but I can build from cmdline!
You can find a different solution at http://getsatisfaction.com/sonatype/topics/_missing_artifact_from_m2eclipse_but_it_is_not_true

Same problem here: I use maven 2.2.1 as the installation to use from eclipse, as it is the one which works on the command line. Maven 3 does not work for this concrete project, complaining about some missing dependencies which, after much research, in my case turned out to come from old maven 1 repositories with legacy layout. Maven 3 hates these and will burst burst into cry when it finds them.

So maven 2 works just fine on the command line, but maven 3 does not. The problem with eclipse is that even if you specify maven 2 as the installation to build your projects, it uses maven 3 (the embedded installation) for dependency resolution, so if you are so unlucky to require a legacy repository you are screwed (I mean, eclipse won't help).