RE: How to Connect to Dynamics GP from Java
There is no specific way to get this data using Java as such.
Your summary options are:
1. Use a SQL type query run by the Java application to periodically query the relevant GP data and present it for upload to your applicaion.
2. Write your own triggers to run when new data enters the relevant GP tables (Not advisable unless you have no other options).
3. Use eConnect to export data as the event happens in GP. If its Sales Orders / Purchase Orders etc then this is probably your best option. (Remember, Microsoft could change the underlying GP tables in new releases - using eConnect protects your initial investment in setting up these 'outegrations'...if you write your own triggers or base it on queries - these may have to be revisited when you upgrade GP).
Your choice between 1 and 3 depends on how you need the data presented - in real time or in batch, Just new records or all records and the Java applicaion synchronises etc.
The question of whether its strictly .net or Java is really too broad to answer here. In a way its not really a choice between Java and .Net. It would require proper analysis of requirements before one could advise you - If GP / eConnect / SQL is not your area of expertise, you could do worse than engage with a willing GP Partner.
Best regards,
Ian.