Okay, so let's pretend that you wanted to make a sandwich. Imagine that the sandwich is a big computer program and the ingredients are like little parts of the program that you have to put together.
Composite application service assembly is like putting together a sandwich. But instead of bread, lettuce, cheese, and meat, you have different computer programs that need to work together.
So, let's say you have three different computer programs that you want to use in your big program sandwich. One program, let's call it PB, spreads peanut butter. Another program, J, spreads jelly. And a third program, B, toasts bread.
You can't just put all three programs on top of each other and hope they work together. You need to assemble them in a certain order. You need to toast the bread first, then spread the peanut butter, and then the jelly.
Composite application service assembly is like making sure all of these little programs work together in the right order. You have to program it so that when you press a button, it knows how to put the different programs in the right order and make them work together.
It's like having a recipe for a sandwich that tells you what order to put the ingredients in. Composite application service assembly is like making sure all the different parts of the computer program work together in the right order.