How to Connect to Dynamics GP from Java

I have a need to connect to Dynamics GP from Java to pull/update information. What is the best way of doing it.

I see that their is something called econnect - which provides different ways

1) MSMQ, 2)BixTalk etc.

Which is the best way to connect? We don't host Dynamics GP, we just need to integrate to our clients Dynamics GP to pull/update data.

Thanks