First in, first out: messages are processed in strict order. Service Bus achieves this with message sessions, which Storage queues can't offer.
Also called first in, first out.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains FIFO in context, with comparison tables and the common traps.
Terms in this definition
- Agents (classic) API
First-generation Foundry Agent Service API, based on threads, messages and runs. It is deprecated, replaced by conversations and responses, and retires on 31 March 2027.
- Service Bus
Azure's enterprise messaging service, offering topics and queues, transactions, dead-lettering and session-based ordering.
- Message sessions
Feature of Service Bus ensuring that related messages carrying the same session ID are processed in first-in, first-out order.
- General-purpose v1
The older storage account kind (
Storage), which lacks access tiers, Archive and premium file shares and retires on 13 October 2026. Converting to ZRS requires first upgrading to GPv2, a one-way change.
Related terms
- BOM
Bytes placed first in a text file to signal its encoding. Fine-tuning data should be saved as UTF-8 with a BOM, keeping each file below 512 MB; ASCII, UTF-16 or ISO-8859-1 files risk failing validation.
- L1L2
A Data API builder caching level that looks first in the in-memory level 1 cache, next in the distributed Redis level 2 cache and finally in the database. Cached entities use it by default; L1 on its own means in-memory caching only.