2.1 Introduction
A request is a message that describes a unit of work for the system to execute
An application server coordinates the flow of requests between message sources (displays, applications, etc.) and application programs that run requests as transactions.
Basic control flow:
- Translate the display input (form/menu selection, etc.) into a standard-format request.
- Send the request to the appropriate server based on the transaction type in the request header
- Start the transaction
- Invoke the transaction type’s application program
- Commit and send the transaction’s output to the display