Thanks for clarification. In that case, I can happily use JAVA APIs and forget about SOAP urls (secure.authorize.net and api.authorize.net)
I am planning to perform the following steps to integrate AIM. Please confirm whether my process is correct:
Development
1) Create Sandbox account and obtain API Login Id and Transaction Key.
2) Use JAVA APIs (anet-java-sdk-1.8.1.jar) to integrate AIM. APIs use API Login Id/Transaction Key secured in a File/Data Base.
3) Execute code and confirm results in Sandbox Merchant interface.
Production
1) Create real Merchant account and obtain API Login Id and Transaction Key.
2) Replace previous values with production API Login Id/Transaction Key secured in a File/Data Base
3) Enable "Test Mode" in real Merchant account.
4) Execute code and confirm results in real Merchant interface.
5) Once I am comfortable, disable "Test Mode" and make it real.
Thanks for your time as this can be a guide line to many followers.