Responding to this older thread in case it might be useful for others or still relevant for the original poster.
It appears the intent is to implement a real time integration between Salesforce and the AS400 based ERP (JDE). If Salesforce information is enough to create the order automatically, then the better approach is to create that order in JDE based on AS400 event behind the scenes. We have integrated Salesforce order entry with AS400 ERPs (including JDE) with the help of Mulesoft middleware - please see more details and the code example here:
https://www.infoviewsystems.com/connect-ibm-i-as400-to-salesforce-with-mulesoft/
If however the user must complete the order entry in JDE as the Salesforce info is not enough for the initial order, here's one way to attack it that we successfully implemented for a high volume call center automation use case:
- Agent is logged both into Salesforce and into a custom AS400 screen app that listens for Data Queue events with the message key unique for each active agent
- When Salesforce button is clicked or based on any other action, Salesforce sends the event message to AS400 data queue
- When message arrives from Salesforce to the data queue, the app will forward to an appropriate AS400 screen and pass the order details received from Salesforce in Data Queue message
- Agent continues with order entry on AS400 side
Basically the user experience is: press on Salesforce button (or mark the opportunity closed - won or whatever is the trigger on SFDC side), then switch to AS400 terminal, and there it will already be an order screen pre-filled with SFDC data.