Example for reference I am going through a requirement where I need to store a key with another association my problem can also be solved by creating a sequential array with a key, but I am not able t

I am unclear on why you are unable to do this. In Eclipse, I go to File->New->Object Model Entities and choose Object. In the class field of the object editor, I choose association and it pops up a dialog for "from" and "to". I choose from String, in the to field I choose association, and it pops up another dialog. In that one I choose from string to integer, and then it populates the full class as association from string to association from string to integer. Similarly, for the array, I just choose array in the drop down for the "to" field and then enter real in the dialog that pops up for the type of the array. These drop downs can get quite large if you have a complex object model, perhaps you just didn't scroll it down far enough to see the array and association options, they are shown in bold type nearer the bottom. Your other issue seems to be creating a class from within a function definition. I believe dynamic creation of classes is not allowed, you need to create a new Object Model Entity of type Class and define it in the class editor.