Java RFC Connection: Step by step

Hi folks,

my first goal is to achieve a remote function call from Java to SAP or the other way.

My first attempt is a Java application which does a RFC to a SAP ABAP function that returns me some database data, but more about that later.

The first thing where i already fail is to build up a simple connection between Java and SAP.

I tried it with JCo v2.1.x and JCo v3.x (Which version should i prefer? are there advantages, disadvantages?)

Here are the two approaches:

{JCO v2.1.x}:

          
JCO.Client myConnection = JCO.createClient("001",                                                               "***",                                                                "****",                                                                "DE",                                                                "***",                                                                "00");
myConnection.connect();
...
...

I get a "(103) RFC_ERROR_LOGON_FAILURE: Userid or password incorrect". I put in my normal SAP GUI account. Its not an admin account but i can create reports etc in the ABAP Editor.

I checked the spelling several time and it should be ok. Why does it say incorrect user or password?

Is this possible because of insufficient rights?

{JCo v3.x}:

I just tried the "StepByStepClient" example included in the sapjco3 download and i saw that every connect function begins with a "JCoDestination destination = JCoDestinationManager.getDestination(String);" line.

But what exactly does this getDestination function do? What string do i pass there? In the example is it JCoDestinationManager.getDestination("ABAP_AS_WITHOUT_POOL"); but then i get the error: ""(106) JCO_ERROR_RESOURCE: Destination ABAP_AS_WITHOUT_POOL could not be created:"..

Can anyone explain me how this works?

Thanks in advance!