Nathan and Paul,
... he may assumed that node.js was running in the "native" virtual 
machine environment and could simply "call" ILE programs directly, 
rather than "using a connection"
I knew Toolkit for i used XMLSERVICE under the covers. So I didn't expect node apps to be able to call CL, RPG or COBOL programs like these latter three types of programs call each other. What I didn't understand was why the node app appears to make a *database* connection in order to execute a CL command. 
I've used JTOpen (Toolbox for Java) a couple of times, and it establishes a connection to the system based on the system name, like this:
import com.ibm.as400.access.*;
AS400 system = new AS400(mySystemName, myUserName, myPassword);
Once you establish the connection, you can immediately execute a CL command like this:
CommandCall command = new CommandCall(system);
command.setCommand("DSPSYSSTS");
Maybe JTOpen is actually establishing a database connection, but that isn't apparent from the code. I was just kind of surprised that node appears to establish a database connection to execute a CL command. It made me realize I probably need to learn more about the underlying technology stack. 
I've gotten a lot of replies with good leads. I need some time to digest the replies and read the suggested links. 
 
Thanks,
Kelly
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