Online transaction processing
Handling many small pieces of work in real time while someone waits: a card payment, a balance check, a seat booking.
Also written OLTP, online processing
Online transaction processing, usually shortened to OLTP, is the other half of mainframe work alongside batch. Where batch runs in bulk overnight, OLTP responds immediately to a request, while a customer or a member of staff waits for the answer.
Each unit of work is small and short: check a balance, move money between two accounts, reserve a seat. What makes it demanding is the volume and the correctness requirement. A large bank may handle thousands of these a second, and every one has to either complete fully or not happen at all. Money must never be taken from one account without arriving in the other.
On z/OS this work usually runs inside a transaction manager such as CICS, which handles the screens, the queuing and the guarantees around committing or backing out changes.
If you have used a cash machine, tapped a card in a shop, or checked in for a flight, you have almost certainly triggered a mainframe transaction of this kind.
Related terms
- CICSThe transaction manager that runs online mainframe applications, and the software behind a great many screens bank staff use.
- CICS transactionOne unit of online work in CICS: the whole exchange of receiving a request, doing the work, and sending a response.
- Batch processingRunning work in bulk, without anyone watching, usually on a schedule. The overnight run that settles a day of transactions.
- Commit and rollbackMaking a set of changes permanent together, or undoing them together, so a transaction never half-happens.